Cornell University Library ^ -^ TH443.T75 1921 ^ ^ "C ^ ^ ^ ^..^U^ '' Safety in building construction. iiuiiiiiiiiiiiiniiiiiiiiiiii iiiiiiiiiiiiiiiiJiiH 3 1924 002 408 759 a SAFETY IN Building Construction SECOND EDITION THE TRAVELERS INSURANCE COMPANY HARTFORD, CONNECTICUT The' The' Create, con usu CORNELL UNIVERSITY LIBRARY NEW YORK STATE SCHOOL OF INDUSTRIAL AND LABOR RELATIONS THE GIFT OF LYNN A. EMERSON iny my lies, oth ^_.., _ ^... tion and service are the highest. It has always led in enlightened methods — indeed has been the originator of a great part of the progressive ideas that underlie modern insurance. THE TRAVELERS INDEMNITY COMPANY {owned and controlled by the parent organization) WRITES INSURANCE ON THE FOLLOWING LINES: AUTOMOBILES and TEAMS STEAM BOILER ENGINE PLATE GLASS BURGLARY THEFT PAYROLL HOLD-UP In whatever field, whether that of compensation and liability, property damage, or life, accident and health, TRAVELERS policies are the standard. Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924002408759 SAFETY IN Building Construction THE TRAVELERS INSURANCE COMPANY ' HARTFORD, CONNEQICUT 21954 2-14-21 . . Ij Copyright, 1916 and 1921, by The Travelers Insurance Company Hartford, Connecticut (Second Edition, Revised.) PREFACE So far as we are aware, the edition of "Safety in Building Construction'" that was pubHshed by The Travelers Insurance Company in 1916 was the first book to be issued in which accident prevention in connection with construction worlv was discussed in a manner even roughly adequate to the importance of the subject. In the five years that have since elapsed, various improvements have been made in the methods and practices employed, due to more extended ex- perience and to a more careful investigation of the causes of accidents in this line of work. The present edition has been brought up to date with respect to these innovations, and several sections have been ex- panded so as to give a more detailed description of certain hazards and the remedies for them. An entirely new section on ''Mixing and Pouring Concrete' has also been added. As previously explained, this is by no means a complete treatise on the subject of safety in building construction. Many of the most dangerous operations are covered, however, and if all of the suggestions that we give are carried out, the number of accidents will certainly be reduced to a small fraction of the number that now occur. We have attempted to make our recommendations comply in every respect with existing building codes; iv PREFACE but if it is found that any of them conflict with the laws, ordinances, or codes in force in a given locahty, it is important to comply with the legal requirements, in every case, in preference to the suggestions made herein. The Travelers Insurance Company, Hartford, Connecticut. CONTENTS. (Paragraph numbers are given on the left, and page numbers on the right.) Section I. Demolition Work: 1. In general, 2. Planning the work, . 3. Shoring adjoining buildings, 4. Gas and electricity, 5. Order of procedure, 6. Fence guards and sidewalk sheds, 7. Removing material from upper floors, 8. Material chutes, 9. Removing walls in sections, 10. Storing salvaged material, 11. Use of the oxy-acetylene cutting-flame, 12. The safe handling of welding and cutting equipment, 13. Miscellaneous, ...... 1 1 2 2 3 4 4 6 7 8 11 13 14 17 Section II. Excavation Work: . 14. General suggestions, 15. Steam sho\'els. Section III. Protection for the Public: 16. Sidewalk sheds and bridges, 17. Location of contractor's office, 18. Street coverings, 19. Protective platforms, 20. Protecting pavements, 21. Storing materials in the street, 22. Excluding persons from buildings. 19 19 23 26 26 26 30 30 31 32 33 Section IV. Hoisting: 23. Location and protection of hoisting engines, 24. Types of hoisting engines, 25. Boilers, 26. Electric motors, 27. Signaling systems, . 28. Protection of signal cords, 34 34 36 36 38 40 42 vi Contents 29. Hoisting cables and sheaves, ...... 44 30. Material hoists, 47 31. Hoisting towers, 57 32. Passenger hoists. 61 33. Slings, .... 65 Section V. Derricks: ........ 75 34. Types, .... 75 35. Stiff-leg derricl;s. 75 36. Guy derricks, . 79 37. Breast or house derricks, . 86 38. General precautions in the use of derricks, 89 Section VI. Scaffolds: ........ 91 39. Introductory, . 91 40. Pole scaffolds, 91 41. Suspended scaffolds. 95 42. Outrigger scaffolds, . 101 43. Horse scaffolds. 102 44. Riveters' scaffolds, . 106 45. Painters' scalfolds, . 106 46. In general. 108 Section VII. L.adders, Stairways, and Runways: . . . 113 47. Ladders 113 48. Stairways, . . . . . . . . .118 49. Runways, ......... 120 Section VIII. Steel workers: . . . . . . .124 50. Erecting gangs. 124 51. Erecting floors. 126 52. Rivet-heaters' platforms, . 126 53. Throwing rivets, 126 54. Pneumatic hammers. 128 55. Care of air hose. 128 56. Handling structural steel. 128 Section IX. Mlxing and Pouring Concrete: .... 129 57. In general, ...... 129 58. Mechanical mixers and their hazards. 129 59. Wheelbarrows and runways. 132 60. Storing and handling sand and stone. 133 61. Concrete towers and distributing chutes. 135 62. Miscellaneous, . 140 Contents vu Section X. GeneRjVL Precautions: ...... 142 63. Covering floors, ........ 142 64. The nail hazard, ........ 147 65. Hand tools 149 66. Wheelbarrows, ........ 152 67. Explosives, ......... 153 68. Life lines and safety belts, ...... 155 69. Storing and piling materials in buildings under construction, . 157 70. First-aid and hospitals, ....... 159 71. Sanitation, ......... 160 72. Miscellaneous, ........ 161 73. Inspections, ......... 164 ILLUSTRATIONS. (The numbers of the illustrations arc given on the left, and the page numbers on the right.) 1. Strengthening building walls on demolition work, 2. Method of lowering floor beams in demolition work, 3. A wooden material chute, .... 4. Wooden chutes (or demolition work, 5. A metal chute in position for discharging, 6. A metal chute in the closed position, 7. Demolishing a brick wall, .... 8. A dangerous pile of bricks, .... 9. A sidewalk shed which collapsed from o\-erloading, 10. A dangerous floor opening, .... 11. Damage to building caused by excavating, 12. Damage to building caused by excavating, 13. Substantial and well-constructed shoring for an excav 14. Guard to intercept objects falling from windows, 15. Catch-scafTolds on the Woolworth Building, 16. One of the platforms shown in Fig. 15, 17. A poorly-made protection for a sidewalk, 18. Unsafe piling of hea\'y steel girders, . 19. Hoisting under dangerous conditions, 20. Unprotected hoisting motor, cables, and guide blocks, 21. Manual signals for hoisting, .... 22. Signal cords inclosed in iron pipes, 23. Protection for the signal cords, 24. Protection for lead blocks and cables, 25. An effective guard for hoisting cables, 25. An approved type of material-hoist fencing, 27. An unguarded shaftway for a material hoist, 28. An unprotected material hoist and shaftway, 29. Dangerous hoistway openings, 30. Protection, near the ceiling, about a hoistway, . 31. Working without the ceiling protection, . 32. Overhead covering for the shaftway of a material hoist 33. Overhead covering for the cage of a material hoist, 34. An iron stairway broken by a falling load of material 35. An external material hoist, .... 36. A pair of well-constructed material hoists, 3 4 7 8 9 9 10 11 12 17 20 21 22 27 28 29 31 32 35 37 41 43 44 45 46 48 49 50 51 52 53 54 55 56 59 60 Illustrations 37. Preventing dangerous crowding at an elevator entrance, 3S. Lined up to enter the elevator, 39. Protection for a passenger-hoist shaftway, 40. Illustrating the obliquity of slings, 41. Illustrating the obliquity of slings, 42. Illustrating the obliquity of slings, 43. Illustrating the obliquity of slings, 44. Illustrating the obliquity of slings, 45. Illustrating the pressure of the sling against the load 46. Illustrating the use of wooden corner-pieces, 47. Diagram of a stiff-leg derrick, 48. Diagram of a guy derrick, 49. Steel derricks used for erection work, 50. Warning signs attached to derrick guys, . 51. Wire-cable slings for anchoring derrick guys, 52. An approN'ed method for anchoring derrick foot-blocks, 53. Diagonal stays for anchoring derrick foot-blocks, 54. Diagram of diagonal stays for derrick foot-blocks, 55. A breast derrick with unprotected gears, 56. Breast derricks used for setting stone, 57. Broken boom of a steel derrick, 58. A bricklayers' pole scaffold, 59. An independent pole scaffold, . 60. A well-braced independent pole scaffold, 61. Suspended scaffold, with platform-type machines, 62. An overhead-type scaffold machine, 63. Supports for overhead-type machines, 64. A hazard in the use of suspended scaffolds, 65. A well-constructed outrigger scaffold, 66. A dangerous method of supporting a horse scaffold, 67. A well-designed horse, .... 68. Wreck of a horse scaffold, 69. A painters' scaffold with a single guard-rail, 70. A painters' scaffold with double guard-rails, 71. Machine for use with painters' scaffolds, 72. A study in dangerous scaffolding, 73. Builders' portable cleat ladder, 74. A poorly-constructed ladder, . 75. A dangerous stairway, 76. A dangerous condition on a stairway, 77. Temporary treads for a stairway, 78. A stairway which invites accidents, 79. A steep single-plank runway, . 80. Steelmen being lifted to their work, 81. A workman taking unnecessary chances, 82. Guards for a concrete mixer, . 63 64 65 68 69 69 73 73 77 78 80 81 82 83 84 85 87 88 89 92 93 94 96 97 98 100 101 103 104 105 107 108 109 110 114 116 119 120 121 122 123 125 127 130 Illustrations XI 83. A large self-propelled concrete mixer, 84. Concrete towers and distributing chutes, 85. Wear goggles when cutting concrete, 86. Goggles broken by a flying chip of concrete, 87. Protective plank flooring in a ventilating shaft, 88. A dangerous floor-opening, ..... 89. An accident-source that is frequently overlooked, 90. An unguarded elevator shaftway, .... 91. Approved guard-rails for permanent elevator shaft ways, 92. Dangerous treatment of a projecting nail, 93. Correct method of hammering down a nail, 94. The nail hazard in construction work, 95. A bar-guard on a material hoist, .... 96. A wheelbarrow accident on a material hoist, 97. Working under dangerous conditions, 98. Painting the steelwork of a "skyscraper," 99. Poorly-piled floor tiles, ..... 100. Keep all material away from the edges of floors, 101. A cloth screen for stopping flying chips of stone, 131 136 139 140 142 143 144 145 146 147 147 148 150 151 156 157 158 162 163 SAFETY IN BUILDING CONSTRUCTION I. DEMOLITION WORK. 1. In General. In many cases it is necessary to remove existing buildings before any actual construc- tion work can be done. The wrecking of a building appears to the casual observer to be a simple and easy task, but it nevertheless calls for experience and skilly because there are many dangers connected with it, even when the structure to be demolished is quite small; and in the case of a large structure these hazards are multiplied many times. The prevailing tendency toward specialization in industrial and other operations has extended to demoli- tion work, so that we now find, in many of the larger cities at all events, contracting firms which have developed organizations for handling this particular work, and have devised methods for carrying it out in a highly efficient and expeditious manner. When the services of such an organization are available it is usually economical to employ them, and the probabil- ities of accidents should also be reduced, as a result of the experience of the men in charge of the operations. 2 THE TRAVELERS INSURANCE COMPANY Whether or not demoHtion work is done by speciaUsts, every such job should be supervised by a person of sound judgment, who should also be capable of handling the working force competently and effectively. The men should be selected, so far as possible, with reference to their capabilities, and each should be assigned to the particular kind of work for which he appears to be best fitted. 2. Planning the Work. Before beginning the actual work of demolition, a careful study should be made of the structure that is to be torn down, and of its surroundings; and a definite plan of procedure should be mapped out, which should thereafter be followed as closely as possible. This is specially important when haste is essential, because the work can be executed much more rapidly and safely when it proceeds in accordance with a definite scheme than when it is carried out in a haphazard manner. In formulating the plan it is necessary to consider the security of adjoining buildings, and to make adequate provision for their safety. 3. Shoring Adjoining Buildings. Extensive shor- ing of other buildings is often imperative, and full provision should be made for carrying out all neces- sary operations of this kind promptly and thoroughly, and in a safe and workmanlike way. As a rule, how- ever, the demolition work, when done by a firm which specializes in these operations, is considered completed when the building has been razed to the sidewalk level, and such shoring operations as may be necessary in removing or altering the foundations are performed by some other contractor. The precautions to be taken in connection with work below the sidewalk level are DEMOLITION WORK 3 therefore more properly included in the section describ- ing excavation work. (See paragraph 14.) Occasion- ally, however, the removal of a building weakens the side walls of the structures immediately adjoining it, and to prevent possible damage in such a case, the demolition contractor may use some of the floor beams of the wrecked building to prop up these walls, until such time as permanent protection can be provided. Furthermore, if a structure has been partially wrecked by a fire, ffood, explosion, or other catastrophe, it may be necessary to shore up or brace some of the walls of the building that is to be taken down, before the wrecking operations can be safely started. A condition of this kind calls for special consideration. 4, Gas and Electricity. Make sure, at the very outset, that the gas pipes have been disconnected, and that all electric wires in the building are "dead." F"iG. 1. Floor Beams from a Demolished Building Joined Together and Used for Strengthening the Walls of Adjoining Buildings. THE TRAVELERS INSURANCE COMPANY If a strong odor of gas is subsequently perceived, stop the work until the source of the gas has been discovered, and do not allow the men to look for it with lanterns nor with open lights of any other kind. 5. Order of Procedure. The demolition work should always proceed systematically, story by story; and the work on the upper floors should be entirely completed before any of the supporting members or other important parts on the lower floors are dis- turbed. By proceeding in this orderly manner it is easy to eliminate various dangerous conditions, such as weak and unsupported walls and chimneys, towering above the workmen. 6. Fence Guards and Sidewalk Sheds. Before the wrecking operations begin, protection against fall- ing objects must be provided for persons who pass by buildings that are to be demolished, when such build- FiG. 2. MiCTUOL) OF Lowering Floor Beams in Demolition Work. (Tin.' rope is secured to tlie beam to be lowered and is passed over an adjaeent beam. Pinch- bars are tiien used to pry the ends of the beam off from the walls at either side, and the beam is lowered to the floor by one or two men who slack off on the rope,} DEMOLITION WORK 5 ings stand close to a street or to a much-frequented thoroughfare of any other kind. Under some condi- tions the entire sidewalk is fenced off for a distance corresponding to the width of the building to be wrecked, and a temporary plank sidewalk is laid in the street and immediately adjoining the curb. This fence keeps passersby out of the danger zone, and all the material that falls during the wrecking operation is confined within the space between the fence and the building. Whenever a fence of this kind is used it should be constructed of boards set tightly together and extend- ing to a height of at least 7 feet, so that passers will be unable to look over or through it, and will therefore have no incentive to loiter in the vicinity. The temporary sidewalk should have a strong railing to prevent persons from being struck by vehicles that might approach too closely if no railing were provided. In place of the arrangement just described it is much more common to construct a shed, covering the entire width of the sidewalk in front of the property. Struc- tures of this kind must always be strong and substantial, because it frequently happens that heavy objects fall upon them from considerable heights. Moreover, materials are sometimes stored upon the tops of these sheds (although this practice is not to be recommended) and for this reason, also, substantial construction is essential. (See paragraph 10.) It is advisable to install a fence and toe-board on the top of the sidewalk shed at its outer edge, to prevent materials or objects of any kind from sliding or rolling off into the street, whether they are stored upon the shed or fall down upon it from above. Stout wire netting having a mesh not larger than half an inch square is 6 THE TRAVELERS INSURANCE COMPANY often used in the construction of these fences, and when netting of this kind is firmly secured in position it answers the purpose admirably. For additional pro- tection against falling objects, strongly-framed wire netting should be installed at either end of the sidewalk shed. This should extend upward from the top of the shed at an angle of about 45 degrees, and out beyond the end of the shed for a distance of from three to five feet. Sidewalk sheds are usually supported on sills 10 inches by 12 inches, or larger. These sills constitute a tripping hazard on the street side of the shed, and in a number of cases persons have fallen over them when passing into the street between the uprights. To elimi- nate this hazard a railing should be secured to the up- rights so that persons cannot pass between them. (See also paragraph 16.) 7. Removing Material from Upper Floors. Ex- cept in isolated locations material should never be thrown to the ground. The danger of this procedure, when the building to be demolished is on a city street, is self-evident, and in addition much valuable material would probably be ruined by throwing it down. Lum- ber that is to be preserved should be lowered to the ground or to the top of the sidewalk shed by means of ropes or suitable tackle. Laths and broken boards should preferably be tied in bundles and lowered in the same manner, but in some cases they are thrown a short distance on to the sidewalk shed. Care should always be taken to see that no one is in a position to be injured by the falling material. The workmen should be specially forbidden to throw heavy masses or large quantities of material from the upper floors down upon the lower ones. DEMOLITION WORK 7 8. Material Chutes. Wooden or metal chutes should be provided, in all cases, for the removal of bricks and other loose debris, and they should De completely inclosed so that it will be impossible for the material to escape from them before it reaches the bottom. To prevent the descending material from attaining a dangerous speed, the chutes should not extend in an unbroken line for more than two stories. A gate or stop should be placed at the bottom of each chute, and should be provided with suitable means for closing it to stop the flow of material. If material becomes jammed in the chute, do not attempt to loosen it by hand, but use tools of some appropriate kind. Fig. 3. A Wooden Material Chute. (The door or stop at the lower end of the chute is held shut by the wooden bar which ma\' be seen suspended by a piece of rope from the horizontal cross-piece. When the chute is to be loaded with material this bar is wedged between the upper side of the door and the lower side of the cross-piece.) 8 THE TRAVELERS INSURANCE COMPANY Place a danger sign at the discharge end of every chute, and do not permit workmen or other persons to stand near a chute, nor to leave teams near one, except while loading from it. Flashboards of extra height should be placed on motor -trucks or wagons that are to be Fig. 4. Wooden Chutes for DEMOLiTio>f Work. (These chutes are similar to the one shown in Fie. 3. The chute at the left is closed, and that at the right is in position tor discharging its contents. These chutes are provided with aprons which when lowered, as shown at the right, increase the length of the chutes, but do not project over the street when raised to the closed position.) loaded from a chute, to prevent material from bounding into the street. 9. Removing Walls in Sections. Sections of wall should never be loosened and allowed to fall as single masses upon the floors of buildings that are being demolished, because the shock transmitted to the floor may cause it to give way: and chimneys and large sections of wall should never be pulled down bodily. DEMOLITION WORK Fig. 5. A Metal Chute in Position for Discharging. (The chute referred to is in the center of tfie illustration.) Fig. 6. A Metal Chute in the Closed Position. (See aiso Fig. 5.) 10 THE TRAVELERS INSURANCE COMPANY even upon the ground, without taking every possible precaution to avoid accidents, not only to the workmen but also to other persons. When an operation of this nature is about to be performed, a crowd of idle sight- seers usually congregates at the nearest place from which a good view may be had, with but slight regard for their own safety. The man in charge of the work should see that all such persons retire permanently Fig. 7. Demolishing a Brick Wall. (It i^ safer fur a man to ^it down on the wall when doing work ot this kind.) to a place well beyond the danger zone, before the wall is disturbed. It is always better and safer to remove walls part by part, rather than to throw them down bodily. The usual method, when destroying brick walls, is for the men to sit or stand on the walls and loosen the bricks by means of pinch-bars, — the bricks then being dropped to the floor. If, however, the walls are so thin or weak as to make it dangerous to stand or sit upon them to DEMOLITION WORK 11 remove the bricks and stones of which they are com- posed, horse scaffolds or stagings should be erected beside them, for the men to work upon. 10. Storing Salvaged Material. In the process of demolition much material can be saved which may fee^* -^ rr,:5^r.-;;y •s- - - ^rr ; Fig. 8. A Dangerous Pile of Bricks. be used on the new construction or sold to good ad- vantage. Doors and windows, rafters, floor joists, flooring, and lumber of various other kinds, structural 12 THE TRAVELERS INSURANCE COMPANY steel, bricks, and stone, are all of considerable value. If such material is to be used in new construction at the same location, arrangements must be made for storing it temporarily. In the congested district of a large city there is usually no storage space available on the job, and the material must then be carted away. In other cases, however, it is often possible to store a part of it at least, in the street, or on an adjoining vacant lot, or even on some part of the property on @H 1 1 1 1 f i [jm, « ' :'1 ■ : ' .'-^ ismiij P^a^BH^^^ ^^g w Fig. 9. A Sidewalk Shed which Collapsed from Overloading. (During tlic remodeling of tlie building here shown, brieks and otlier materials were stored on the sidewalk shed. The weight caused the shed to collapse, and as a result one man was killed and five others were injured.) which the new structure is to be erected. No matter where it is stored, certain precautions should be taken in piling the material, in order to prevent accidents. Bricks should be cleaned immediately and stored in orderly piles not more than five feet high. The bricks should not rest directly on the ground, but should DEMOLITION WORK 13 be laid on foundations of planks or boards, and the piles should be braced, if necessary, to prevent them from falling over. Nails should be removed from boards, planks, and timbers, and these materials should also be laid up in orderly piles on suitable foundations. Cross strips should be used, whenever necessary, to bind the piles together and provide greater security. If it is necessary, for any reason, to store old material within the building for a time, great care must be taken to avoid overloading the floors. Old material should not be stored on the tops of sidewalk sheds unless the sheds have been specially designed for such a purpose, and even in such cases strict precautions must be taken to avoid overloading. Storing material in this way should be considered as a temporary measure only, and the material should be removed as soon as possible. (See also paragraphs 21 and 69.) 11. Use of the Oxy-acetylene Cutting-flame. In demolishing buildings containing steel beams or other metallic structural elements, the oxy-acetylene flame is now widely used for cutting the metal. Work of this kind should always be done by an experienced man who thoroughly understands the process, and who also has sufficient knowledge of structural principles to avoid cutting off important members that are required for supporting or strengthening the part of the building that still remains standing. Beams that are about to be cut should first be properly secured by ropes or chains, so that they can- not drop or swing when they have been cut away from the other steelwork to which they were attached. When the cut is completed the two ends are often held to- gether by fused oxide, so that a blow from a sledge is 14 THE TRAVELERS INSURANCE COMPANY necessary to separate them. However well the beam may have been secured, it is Hkely to swing slightly when the ends are finally severed, and unless the work- man is watchful his hands may be caught and crushed or bruised. Continued exposure of the unprotected eyes to the acetylene flame acts injuriously upon them, and all operators of acetylene torches should be provided with colored-glass goggles, and should always wear them when working. They should also wear suitable gloves to protect their hands in case of accidental contact with the heated metal. Commercial acetylene is injurious to the health, even when highly diluted with air, and care should be taken to avoid inhaling it. The ventilation at the workplace should be good, and special care in this re- spect should be exercised when using the acetylene torch in confined spaces. The torch consumes considerable oxygen, and impoverishes the air in that way also. Combustible material of every kind should be re- moved from the immediate vicinity of the acetylene torch, because fires may be started by direct contact with the flame, or by the fall of highly-heated pieces of metal or of oxide. Shields composed of incombustible material should be provided to intercept falling pieces of hot metal and oxide, when persons are working directly beneath places where welding or cutting opera- tions are being performed. 12. The Safe Handling of Welding and Cutting Equipment. Special precautions are necessary in con- nection with cylinders or tanks containing compressed oxygen and acetylene gas, if accidents are to be avoided; and all other equipment used for welding and cutting DEMOLITION WORK 15 must be kept in good repair and handled carefully and intelligently. The tanks should never be dropped or subjected to heavy blows or jarring; and they should not be left where they might be knocked over, or where heavy objects might fall on them. Electromagnets should not be used for hoisting compressed-gas tanks, and when lifting or lowering them by means of derricks or other hoisting devices, suitable cradles should be used in place of slings, in order to reduce to a minimum the possibility of dropping the tanks. When compressed-gas tanks are in use they should be located as near as possible to the point where the work is being done, so that long lengths of hose will not be required to connect the tanks with the welding or cutting torches. Tanks should be lashed or otherwise securely fastened in place when the conditions at the point where they are being used are such that they may fall to a lower floor or to the ground, if not so secured. Full tanks should be protected from the weather while in storage; they should not be stored near boilers, furnaces, or other heat-sources, nor should they be ex- posed for any considerable time to the direct rays of the sun, because heat will increase the pressure and may cause the tanks to rupture. Never use open lights or flames of any kind in places where compressed-gas cylinders are stored. Keep all oily and greasy sub- stances away from oxygen cylinders and apparatus. Acetylene tanks should be stored in an upright position, and they should also stand on end when in use. Always close the valves on cylinders that are supposed to be empty, before placing them in storage or shipping them. If a cylinder is received in a leaky condition, leave it out in the open air, but protect it in such a way that 16 THE TRAVELERS INSURANCE COMPANY inquisitive persons cannot be harmed by the escaping gas. Never test for leaks with an open flame, but use soapsuds for this purpose, — the leaks will be indicated by bubbles. The hose should not be connected directly to the gas cylinder, but to an automatic regulator or reducing valve screv/ed on to the outlet of the cylinder valve on the tank. When connecting the regulator to the cylin- der valve make sure that there is no leakage at the joint or connection. To test this joint, first release the pressure-adjusting screw on the regulator and close the needle valve on the outlet of the regulator or on the inlet of the blowpipe. Then open the cylinder valve slowly and test the connection with soapsuds. If there is any leakage, be sure to close the cylinder valve before tight- ening the connection. After connecting a new cylinder of compressed gas, and before lighting the gas at the torch, open the valve on the blowpipe or torch and let it remain open long enough to permit the escape of any gas mixture that may have remained in the hose from a previous operation. If the use of the torch or blowpipe is discontinued but the hose remains connected to the automatic regulator or reducing valve, be sure to close the valve on the tank, to relieve the pressure on the hose. Keep the hose and all other welding and cutting equipment in the best possible condition. Make all connections tight, using suitable clamps or binding wire for the purpose. Hose should be protected when in use so that it will not be trampled on nor heavy objects placed on it. Do not permit it to become tangled or kinked or subjected to severe twists or strains. All equipment that is not in use should be stored in a safe place. DEMOLITION WORK 17 13. Miscellaneous. One of the principal dangers in demolition work is that due to falling objects, and various phases of this hazard have been considered in some of the preceding paragraphs. In addition to the precautions already mentioned we may call attention to the necessity for protecting men who may be working on floors below the level at which the actual demolition operations are proceeding. To prevent injury to these men all floor openings should be kept covered, except Fig. 10. A Dangerous Floor Upening. (Unguarded openings of this kind are often seen on demolition operations. They should always be covered over, or surrounded by railings and toe-boards.) when in actual use for lowering material ; or if this is not feasible, toe-boards and hand-rails should be installed about them. Care should be exercised in handling sheet metal roofing and cornices, because the edges of objects composed of this material may cause severe wounds. For the same reason no broken glass should be left lying about in the building. 18 THE TRAVELERS INSURANCE COMPANY The nail hazard is also an exceedingly important one in demolition work, and should receive much more attention than is usually given to it. As a rule, no attempt is made to remove or bend over the nails in boards, planks, and timbers that are stripped from the building, and doubtless the contractor feels that time cannot be spared to do it. We do not approve of laxity in this direction, and certainly there is no good reason for leaving boards with upturned nails lying about, as is the almost universal custom; because the boards can just as easily be piled with the nails pointing down, and it should be somebody's business to see that this is done. The nail hazard is considered in further detail in paragraph 64. In demolishing buildings, stairs and stair railings should be left in place as long as possible, and be used for going up and down. Stairways are much safer and more convenient than ordinary ladders. Dust resulting from demolition operations causes much annoyance and discomfort, and it is likely to get into the workmen's eyes and create more serious trouble. Floors, chutes, stairways, and various other places should therefore be sprinkled with water as often as may be necessary to keep down this dust. II. EXCAVATION WORK. 14. General Suggestions. The work of preparing the foundations for a building is too important to be fully discussed in this book; but there are certain suggestions with regard to excavating which may properly be included, and which will make the work much safer if they are followed. Special precautions should be taken to avoid under- mining the foundations of adjoining buildings. If the foundations of the building that is being razed extend below those of the neighboring buildings, only short sections should be removed at one time. The neigh- boring foundations may then be undermined, also by small portions, and extended to the level of the new foundations. If necessary, the foundation walls of the adjoining buildings should be substantially shored up or braced, or other effective means should be adopted to prevent the walls from settling or being damaged in other ways. It is also important to thoroughly prop up or brace the walls of excavations on the sides ad- joining public streets, and at all other points where there is danger of the caving-in of the earth. In loose soil, and also when foundations extend to a consider- able depth, it is often necessary to use sheet piling. Excavations should be guarded on all sides by fences or railings; and all rocks, boulders, loose soil, and material of every kind should be kept back at least four feet from the edges of the openings. 20 THE TRAVELERS INSURANCE COMPANY Fig. 11. Damage Caused by Excavating Without Ade- quately Shoring the Wall of the Adjoining Building. EXCAX'ATIOX ^\■ORK 21 Fig. 12. Another View of the Building Shown in Fig. 11. (Note the crude and unsafe ladder at the right of the engraving.) 22 THE TRAVELERS INSURANCE COMPANY Inspect the walls of excavations frequently and thoroughly, particularly after heavy rainstorms, and do not let the employees work at any point where a cave-in seems probable, or where other recognizable sources of danger exist. In particular, do not permit anyone to work under an overhanging mass of earth or rock that has not been made safe by the use of shores or props or other supports of undoubted strength and effectiveness. When motor-trucks or horse-drawn wagons are used on the work, provide suitable inclines of ample width for trucks or wagons loaded with the excavated material, and see that proper precautions are taken to prevent the vehicles from tipping over. Whenever possible, the excavation work should be Fig. 13. Substantial and Well-constructed Shoring for AN Excavation. EXCAVATION WORK 23 entirely completed before any building material is stored on the premises. Sometimes structural steel, timbers, brick, tile, and other materials are deposited in the partly-finished excavations, often with insuf- ficient care in storing and piling them, and these increase the difificulties and dangers of the work. Suggestions Avith regard to storing material are given in paragraphs 10, 21, and 69. Various mechanical appliances are used in exca- vation work, including derricks and steam shovels. The chief precautions to be taken in the operation of derricks are described in Section V. Explosives are often used in excavating operations, and these are likely to cause serious accidents unless they are handled carefully and intelligently. Some of the necessary precautions to insure safety in the hand- ling of explosives are described in paragraph 67. 15. Steam Shovels. The steam shovel is a prolific source of serious accidents. Many of these result from the breaking of the ropes or cables. When a cable gives way, the engineer is likely to be struck by the loose, fiying end, unless a protective device of some kind is placed between him and the winding drum. A satisfactory guard may be made of heavy wire-mesh screen secured to a stout iron framework. This forms an effective protection that will not interfere with the engineer's work, nor obstruct his view. The necessity for oiling the sheaves or making repairs at the point of the boom has led to many accidents. Workmen, encumbered with oil cans and tools, often fall when climbing out to the boom end, and receive serious injuries. Ladders or steps (pro- vided with hand-rails when this is practicable) can be 24 THE TRAVELERS INSURANCE COMPANY placed on the booms without interfering with the operation of the shovels, and in this way much of the danger attendant on the care of the booms can be eliminated. The crank-shafts, as well as all exposed gears and set-screws, should be guarded or covered, even though no employee approaches these parts in the ordinary operation of the shovel. The hoisting chain or cable, at the bottom of the boom, should also be guarded. This part of the apparatus may be out of reach of any- one on the ground level, yet it may cause an injury to a man on a wagon or motor-truck as the boom swings around. All ladders, steps, handholds, and other similar safeguards should be kept in a good state of repair. Snow, ice, and slippery mixtures of dirt and grease, should be removed; and oil-cans, picks, and other tools and implements should not be left about where persons may stumble over them. No employee or other person should be allowed on a steam shovel unless his duties require him to be there, and all persons should keep well away from the range of the shovel's swing. This latter precaution is specially important when the shovel is loading material into wag- ons or motor-trucks. Stones, or lumps of other heavy material, are likely to roll off as the shovel swings and drops its load on a wagon, and persons standing near may be injured by the falling fragments. Under some conditions, men may be engaged in drilling and blast- ing operations, close to the point where the shovel is clearing up the material loosened by previous blasts; and in cases of this kind special care should be taken to prevent either crew from injuring the other one. EXCAVATION WORK ■ 25 It is not at all uncommon to see a shovel with pieces of rock projecting over the edge, and these pieces often fall off. It is particularly important, in such cases, for the workmen to keep away from the path of the shovel, and to assist them in doing so the shovel operator should sound the whistle before starting to hoist. Care should be taken to prevent the upsetting of the shovel, which may be caused by an excessive load or by the yielding of the ground upon which the shovel rests. An experienced and cautious shovelman should be able to prevent accidents of this kind without mechanical aids. Under some circumstances, however, it has been found advantageous to secure a U-tube, partly filled with mercury, to some part of the frame- work of the shovel, — arranging the tube so that an electrical connection will be made and a gong sounded, in case the shovel is tilted to a dangerous angle. Every steam shovel should be in charge of a com- petent man having a thorough knowledge, not only of shovels, but also of the operation and care of steam boilers and steam engines. Electricity has recently been introduced, in place of steam, as a motive power for shovels; and where it is used the hazards that are incident to electric power have also to be con- sidered. The rough service characteristic of shovel work calls for frequent and careful inspection of the electrical apparatus, with special reference to the detection of defects that may interrupt the supply of current at critical moments. (See also the sugges- tions with regard to boilers and electrical apparatus, in paragraphs 25 and 26 respectively.) III. PROTECTION FOR THE PUBLIC. 16. Sidewalk Sheds and Bridges. Sidewalk sheds have been described in paragraph 6, to which the reader is referred. Sidewalk bridges are similar in construction, except that they have no roofs, and are sometimes used when the excavations for new buildings extend out to the street line and require the removal of the sidewalks. The fioor of the bridge, in such a case, is usually at an elevation of several feet above the street level, and stairs or steps are provided at each end to give access to it, and thus afford a continuous passage- way in front of the property. A bridge of this kind is preferable to a temporary sidewalk laid in the street, as described in paragraph 6. It affords no protection against falling objects, however, and therefore must be covered over if used on a demolition job; and when employed in connection with construction work, it must also be roofed over as soon as the work has progressed to a greater height than the floor of the bridge. When covered over in this way it is, in effect, a sidewalk shed. Every sidewalk bridge (whether it be covered or uncovered) should be substantial in construction, and strong guard-rails and toe-boards should be installed on both sides of it. Hand-rails should also be installed on all steps leading to these bridges. 17. Location of Contractor's Office. The office of the head contractor, in many cases, is constructed on PROTECTIOX FOR THE PUBLIC 27 lapiiriii' \ ii MwW» <«**'^^ ''^^^ Fig. 14. A Guard to Intercept Falli.ng Tools and Other Objects, ^^'HEN Men are Workinx, about Windows. top of the sidewalk shed or bridge, and for some strange reason is often situated in an unnecessarily dangerous place, where it is likely to be struck by stones or by other objects that may fall to the bridge. Convenience re- quires that the office be near the work, but there is frequently a great difference in the exposure, according as it is built at one part of the sidewalk bridge or at 2S THE TRAVELERS INSURANCE COMPANY Fig. 15. Catch-scaffolds on the Woolworth Building. (The purposi- of tlicse scaffolds is described in (lie lext. See nlso Fiy. 16.) PROTECTION FOR THE PUBLIC 29 Fig. 16. One of the Platforms shown in Fig. 15. 30 THE TRAVELERS INSURANCE COMPANY some other part. Needless hazards of this kind should be avoided. 18. Street Coverings. When the entire adjoin- ing street is roofed over except for openings through which material may be hoisted, hinged hatches com- posed of two-inch planks should be provided for the openings, and these hatches should be raised and low- ered by means of blocks and falls. In addition, guard- rails and toe-boards should be installed on all four sides of the openings, and the whole inclosed with heavy wire netting. These guards should be set back at least two feet from the edges of the openings. 19. Protective Platforms. In addition to the sidewalk shed it is sometimes necessary, on a high structure, to extend protective platforms out from the building at different heights, to catch falling material and prevent it from descending into the street. A platform of this description may advantageously be 15 feet or more in width, and it should be protected along its outer edge by substantial wire-mesh screens, similar to those described in paragraph 6. In the erection of the Woolworth Building in New York City special attention was given to the construction of catch-scaffolds of this kind, and plat- forms 20 feet wide were thrust out from the building at four different heights. These had wire-mesh screens arranged along their outer edges to give still further protection. Fig. 15 shows three of these platforms, and Fig. 16 shows the appearance of the platform at the fif- teenth floor, which is the lowest one of those shown in Fig. 15. The amount of debris on this platform should be noted. Some of the fragments would have produced serious injuries if they had struck persons below. PROTECTION' FOR THE PUBLIC 31 The wire netting at the edge is not supposed to be relied upon for checking the direct fall of materials, but after they have struck the main platform they often rebound somewhat, and the netting is useful in prevent- ing such fragments from bounding or rolling over the edge of the platform. 20. Protecting Pavements. Where heavily-load- ed teams or motor-trucks must be driven across the side- walk, the surface of the walk must be removed or cov- ered over in some way so that it will not be broken. Municipal regulations often require that the street pave- ment also be protected against damage, particularly when it is of sheet asphalt. It is customary to lay heavy planks over the pavements for this purpose, and care should be taken to see that no holes are left into which persons may step, and that the planks are level Fig. 17. A Poorly-made Protection for a Sidewalk. (The broken planks near the curb should be removed and replaced by others that are sound and stout; and the boards on the sidewalk should be arranged so that they cannot tip up at the ends.) 32 THE TRAVELERS INSURANCE COMPANY Fig. 18. Unsafe Piling of Heavy Steel Girders. (These are piled unnecessarily high. Moreover, the pile leans to the right, as shown by the improvised plumb-line.) and are arranged so that they will not tip up at the ends and cause persons to stumble. It is often advisable to lay beveled planks at the sides and ends of protective coverings of this kind, and it is always important to see that there are.no projecting nails or large splinters that might cause injuries. 21. Storing Materials in the Street. When build- ing material is stored in public highways, great care must be exercised to see that it is properly piled, so that it cannot fall over or collapse. It should be disposed PROTECTION FOR THE PUBLIC 33 SO as to obstruct traffic as little as possible, and should in no case cover more than one-third of the width of any public highway. The piles should also be guarded at night by an adequate number of lights, located at conspicuous points. (See also paragraphs 10 and 69.) 22, Excluding Persons from Buildings. All un- authorized persons should be excluded from places where demolition or construction operations are going on, not only because they are likely to be injured, but also because they often interfere with the workmen. When practicable, gates or doors may be installed to keep out all persons not directly connected with the work, or watchmen may be stationed at the en- trances for the same purpose. Special arrangements may be made on behalf of persons seeking employment, either by designating certain hours when they will be admitted, or, preferably, by receiving them at some convenient point outside of the region of danger. IV. HOISTING.* 23. Location and Protection of Hoisting Engines. It is often necessary, at least during the early stages of building construction, to locate the hoisting engines in the public highway. This must necessarily result in obstructing traffic to some extent, and there are also various other objections to this arrangement, so that it is desirable to install the engines within the building as soon as the work has advanced to a stage where it is possible to do so. There are many advan- tages to be gained by placing the engines on the second-floor level, particularly on large construction jobs, because here they are out of the way of trucks or wagons that are often used for bringing supplies and materials into the building. (See paragraph 69 for suggestions concerning the storage of materials in buildings under construction.) Furthermore, this ar- rangement simplifies the protection of the hoisting cables and signal cords or wires. Regardless of the location of the hoisting engines, substantial roofs should be erected over them to intercept falling objects; and it is preferable to entirely inclose them, to protect the operators and the engines from inclement weather, until such time as the per- manent floor immediately above is in place, and the walls of the building have been carried up beyond the floor level on which the engines are situated. When- 'Derricks are separately considered in Section V. HOISTIXG 35 Fir,. 19. Hoisting under Dangerous Conditions. (Persons should not be permitted to walk under suspended loads. The sidewalk: should t>e closed to traffic while loads are being hoisted.) ever the hoisting engines are placed in the street, all large structural steel members and blocks of stone, and all other heavy and massive objects should be hoisted on the side of the building opposite to that on which the engines are installed, when conditions will permit. Serious accidents have occurred when this precaution has been neglected. 36 THE TRAVELERS INSURANCE COMPANY 24. Types of Hoisting Engines. Hand-operated derricks and hoists of various types are quite generally employed on small construction jobs, and for certain parts of the work on larger ones. In large operations, however, steam engines or electric motors are indis- pensable. Provide effective protection for the exposed gears of all hoisting engines and motors, and guard all crank-shafts, sprocket wheels and chains, projecting set-screws and keys, and all other dangerous moving parts. See that a suitable space in the vicinity of hoisting engines is kept clear of unnecessary ropes and other objects that might become caught in the moving parts. If the hoisting engine or motor is installed on a platform or in any elevated position where the space is limited, provide railings and toe-boards at all points where protection of this kind is needed. Provide adequate and effective brakes for every hoisting engine, capable of holding the maximum load in any position. All hoists should be kept under perfect control at all times, and particularly when lowering heavy loads. 25. Boilers. Give special attention to the boilers of all steam hoisting-engines, because the conditions under which they are operated are likely to cause more rapid deterioration than would be the case with sta- tionary boilers. Periodical inspections by experts are essential, and all recommendations made by them should be promptly and carefully attended to. See that each boiler is provided with a reliable safety- valve, steam gage, water column, gage glass, and try-cocks, and test all of these devices frequently to make sure that they are in good working order. An approved gage-glass guard is highly important for each HOISTING 37 Fig. 20. Unprotected Hoistixg Motor, Cables, and Guide Blocks. (Note, also, the state of general disorder that characterizes the woriiplace as a whole.) 38 THE TRAVELERS INSURANCE COMPANY Steam boiler, because the conditions under which the boiler is operated are such that the gage glass may easily be broken. Keep the interior surfaces of the boiler clean, and free from scale and sediment. Provide a suitable strainer or filtering device of some kind if the feed water is likely to contain suspended impurities in sufficient quantity to settle inside the boiler and cause damage. Do not leave the fire door open to check the fire, and so far as possible avoid opening it at frequent intervals for other purposes. Cold air, entering the fire door and coming in contact with the highly-heated portions of the boiler, is likely to cause severe strains which may ultimately result in serious damage. Before leaving for the night make sure that there is plenty of water in the boiler, and that the fire is properly banked and checked; and always ascertain the level of the water before unbanking the fire in the morning. See that all steam and water connections about the boiler and engine are kept tight, to prevent scalds and burns. 26. Electric Motors. Electric motors are rapidly supplanting steam engines for hoisting work in many localities, and their use is particularly desirable in congested districts where the smoke, cinders, and steam from the boilers of steam hoisting-engines would be objectionable. Care must be taken to avoid shocks and burns when electric power is used, and therefore all parts of the electrical equipment should be inspected frequently and thoroughly, to see that everything is in good condition. Never permit unauthorized persons to tamper in any way with electrical apparatus, and see that all repairs and adjustments are made by competent electricians. An electric hoist should always be operated in HOISTIXG 39 Strict conformity with the directions issued by the makers of the apparatus. In certain forms, for ex- ample, it is important to keep the controller handle on the last contact point, after the machine has been brought up to speed, while in other forms it is per- missible to keep the handle at other points, accord- ing to the speed desired. In every case, however, the operator should avoid advancing the handle too rapidly in starting the motor, not only because there is danger of burning out the coils if this precaution is neglected, but also because a too-sudden start may cause severe mechanical strains to be thrown on various parts of the hoisting mechanism. A suitable fuse or automatic circuit-breaker is essential to the safe oper- ation of an electric hoist, and one or other of these devices should be provided in every case, and adjusted to act at not more than 50 per cent, overload. Solenoid brakes form a desirable feature of the equipment of an electric hoist, because they provide an additional safeguard and are well worth the extra expense of installation. These brakes are applied to the armature shaft and operate automatically, but gradually, when the current fails for any reason, and also when the hoist is stopped. Install switches and fuses of the inclosed type Avhenever possible, and do not permit the use of copper Avire in place of proper fuses. See that all switchboards are railed ofif so that no unauthorized persons can get at them, and place rubber mats or coverings of other good non-conducting material in front of the switch- boards, for the operators to stand on. The power is transmitted to the winding drums of electric hoists of some types by means of sprocket wheels 40 THE TRAVELERS INSURANCE COMPANY and chains, and these should be entirely inclosed or otherwise effectively guarded, to prevent the hands or clothing of the operators from being caught. 27. Signaling Systems. In the operation of ma- terial hoists and derricks it is important to have a sig- naling system or method that will be positive and reliable under all conditions. Signaling by motions of the hand (see Fig. 21) may be satisfactory when the signalman can be plainly seen by the hoisting engineer, but relaying the signals from one man to another and thence to the hoisting engineer is likely to result in accidents, due to the failure to transmit the signals correctly. Signaling by means of blasts on a whistle is also unreliable and unsafe, as a rule, because the noise from riveting hammers and from other sources makes it difficult for the hoisting engineer to hear the whistle distinctly. The usual practice on large building operations is to install a bell or gong near the hoisting engine or motor, and to run a signal cord from the bell up through the material-hoist shaftway or near it, or, in the case of a derrick, to extend the cord to a point on the erecting floor where the signalman can plainly see the derrick and observe its movements. In giving the signals for the movements of the der- rick it is customary in many cases to give one stroke of the bell to stop when the derrick is in motion. A single stroke of the bell also signifies that the engineer should start to hoist when the derrick is not moving; and two strokes of the bell are given when it is desired to lower the load. This system may be replaced with advantage by the more modern one of using three different signals, — HOISTING 41 LOWER 2 n II p BO0M DOWN 6 SWING 4 Fig. 21. Manual Signals for Hoisting, as Used in the United States Reclamation Service. (1. Hoist — Forearm vertical. -^lake small horizontal circle with the hand. 2. Lower — • Arm extended, hand below hip, wave forearm downward. 3. Stop — Arm extended, hand level with the hip. Hold position rigidly. 4. Swing Boom Around — Arm extended, forefinger indicating direction of swing. 5. Boom Up — Arm extended, fingers closed, thumb up, jerk arm upward. 6. Boom Down — Arm extended, fingers closed, thumb down, jerk arm downward. 7. Travel — Arm extended, hand open, wave forearm in direction of travel. 8. Make Movement Slowly— l^eft forearm vertical, hand open. Right forearm vertical, forefinger extended near left hand. Make small circle with right hand. 9. Emergency Stop — Arm extended, hand open, palm down. Move hand quickly to right and left.) 42 THE TRAVELERS LNSURAXCE COMPANY two strokes of the bell signifying to hoist, three strokes to lower, and one to stop. This code has the advan- tage of being perfectly definite. It also avoids the dan- ger of giving a starting signal by the accidental fouling of the signal rope, since one stroke of the bell, on this system, has no meaning to the engineer when the load is stationary. A similar system of signals is used in connection with derrick work to indicate desired movements of the derrick boom, — that is, to direct the hoisting engineer to lower the boom or to swing it to the right or left. In such a case it is necessary to have two bells or gongs, and the tone or sound of these bells should be distinct- ly different, in order that there may be no misunder- standing on the part of the hoisting engineer. In very noisy places bell signals may often be ad- vantageously replaced or supplemented by a system of electric lamps, the signals being given by using lamps of different colors instead of by sounding a number of strokes on a bell. 28. Protection of Signal Cords. It is extremely important to guard the cords used for signaling to the hoisting engineer, in such a manner that nothing can accidentally strike them and cause the gong to ring. It is often possible to run them through suitably arranged two-inch pipes firmly secured in place and leading from the hoisting engine to the signalman's station; or they may be boxed in on each floor to a height of not less than 7 feet above the floor. Cords with wire cores should be used for signaling. There should be no knots in them, and when it is necessary to lengthen them the ends should be carefully joined by smooth, strong connections. Inspect the cords frequently for the pur- HOISTING 43 pose of discovering worn or frayed places in them, and add new lengths if any defective portions are found. The breaking of a signal cord at a critical moment may result in serious injury or extensive property damage. Fig. 22. The Signal Cords are Here Lnxlosed in Iron Pipes. (The two 2-inch pipes shown in the center of this engraving extended from the hoisting engine to the erecting floor, and the signal cords were run through them. This method of protect- ing tile cords is strongly recommended.) 44 THE TRAVELERS I^SURA^'CE COMPANY 29. Hoisting Cables and Sheaves. It is equally important to guard the hoisting cables at all points where persons or materials might come in contact with them. When the cables pass along near the floor level they not only present a tripping hazard, but while they are in motion there is also danger that the clothing of passing workmen may be caught. The danger is greatly increased when two hoisting cables that run in opposite directions are placed close together. Fig. 23. Protection for the Signal Cords. (When it is not ptacticable to use pipes as shown in Fig. 22. a guard of this nature should be installed on every floor, where the signal cords are exposed. The framework should not be left open, however, but should be covered with close-meshed wire netting, or its equivalent, so that nobody can interfere with the cords.) HOISTING 45 Provide suitable inclosures for all horizontal or in- clined hoisting cables that are less than 7 feet above the floor level, and also inclose all vertical cables to a height of 7 feet above each floor. Take special care to guard cables that pass over stairways, and over or through passageways, and near ladderways. Workmen carrying Fig. 24. An Approved Method for Protecting Lead Blocks and Cables. (The cables were boxed in where they ran along near the floor level, and the lead blocks were inclosed, as shown. The general floor conditions could be improved.) planks, boards, and other materials are likely to be in- jured by having their loads caught by the moving cables, unless efficient protection is provided. Take special precautions to prevent cables from chafing or rubbing against steelwork, floor tiles, and other objects. Cables that pass through floors com- 46 THE TRAVELERS INSURANCE COMPANY posed of tile or concrete should be protected by wooden boxes about 8 inches square, set in the floors. Inspect all cables frequently and thoroughly, and replace any that are found to be dangerously worn or fraj'ed, or partially broken. With hoisting appara- tus it is not always practicable to use sheaves as large as a proper regard for the relation between the size of the sheaves and the diameter of the cables would require, and the cables are therefore subject to bending Fig. 25. An Effective Gu.\rd for Hoisting Cables. fA similar guard, at least seven feet high, should be installed on every floor. The frame- work should be covered with wire mesh, however, so that the aibles cannot be touched by hand.) HOISTING 47 strains much more severe than they would experience if the cables and sheaves were correctly proportioned. This results in shortening the useful life of the cables, and makes careful inspection exceedingly important. Blocks that were originally designed for use with manila ropes are sometimes used with wire cables. This is a bad practice, however, and should be pro- hibited, because the cables often do not fit the grooves in the sheaves, and both the sheaves and the cables are therefore subjected to undue wear. Blocks that are used to change the direction of the cables, and that are located near the floor or in other exposed places, should be inclosed or otherwise effectively guarded so that nothing can be drawn into them. Provide ample and suitable lubrication for all sheaves and pulleys, and see that they are properly alined so that the cables will not run off. Whenever possible, the blocks should be equipped with self- lubricating cast-steel sheaves. Test all cast-iron sheaves and pulleys frequently with a hammer, to make sure that none of them are cracked or broken. 30. Material Hoists. All material-hoist openings should preferably be tightly inclosed throughout their entire length, and the entrances to them at each floor should be protected by vertical-lift gates of ample height, which should always be kept in position. When this is not practicable, the sides of the hoistways not used for entrances should be inclosed at each floor to a height of at least 8 feet, with wire netting of not less than No. 10 United States standard gage, and having openings not greater than \}4 inches each way, and preferably smaller. When two material hoists are installed close together, similar protection should be 48 THE TRAVELERS INSURANCE COMPANY provided between the hoistways, as shown in Fig. 26. The entrance sides should be protected by bar- guards of sound, strong wood, not less than 2 in. by 3 in. in section, placed at a height of 3 feet above the floor, and at a distance of 16 or 18 inches from the edges of the openings. Each bar should be bolted to the hoist fencing at one end by a single bolt on which the bar I'lG. 26. An Approved Tvpe of Material- hoist Fencing. (This is composed of substantial wire netting, with a half-inch mesh. The engraving shows the adjustable bars, placed at a safe distance from the edges of the hoistway, and also, though not very clcarlj', the wooden buttons for holding the bars in an upright position while loading the hoists.) may swing, and a hook or wooden button should be provided, to hold the bar up out of the way while loading or unloading the hoist. A slot should be provided at the opposite side of the hoist fencing, to receive the end of the bar when it is lowered to its normal position. Fences or barricades of slat construction are some- HOISTING 49 Fig. 27. An Unguarded Shaftwav for a Material Hoist. (Note the absence of railings and other protective features about the opening. Moreove bricks and other objects phould not be left lying about near openings through which they may fall upon persons below.) 50 THE TRAX'El.ERS INSURANCE COIMPANY ViG. IS. An Unprotected Material Hoist and Shaftwav. (The floor opcniiiKs at the Kirles of tfie lioist sfiould fie covered over, and ttie sliaftway and tioist sfiould hG guarded as indicated in paragrapli 30.) HOISTING 51 times used for hoisting inclosures, but these are less desirable than the other forms of protection already described, because there is danger that small objects may fall between the slats. If inclosures of this kind are used, the slats should be spaced not more than 4 inches apart, and the fences should extend to a height of at least 8 feet above the floors. Bar-guards should be provided, similar to those recommended for use with the wire-mesh barricades. Fig. 29. D.\xgerous Hoistw.a.y Ope.xixgs. (Tlic bottom of the stairwa\- in the backErround is cio^e to the unguarded openings. Observe that tile lower stair-tread is missing and that floor tiles are used in plaee ol' it,} The guide rails of the hoists should be kept rigid and in correct alinement at all times. This is a point to which proper attention is seldom given, and yet it is most important. Install protective coverings above the overhead work of all material hoists, to prevent objects from falling down the hoistways, — these coverings to be re- moved and replaced whenever the increased height of 52 THE TRAVELERS INSURANCE COMPANY Fig. 30. Protection, near the Ceiling, about a Hoistway. (This protection is for tlie benefit of lattiers, plasterers, electricians, and others who are required to work in elevated positions near hoistways. See also Fig. 31.) HOISTING 53 Fig. 31. Showing the Danger of Working without the Protection Illustrated in Fig. 30. 54 THE TRAVELERS INSURANCE COMPANY Fig. 32. Protecti\e Covering for the Overhead-work of A Material Hoist. HOISTING 55 the building necessitates changing the location of the overhead sheaves of the hoists. Also, install framed covers of planking or heavy wire mesh on the crossheads of all material hoists, to prevent falling objects from striking workmen when loading or unloading the hoists. These covers should be made in two sections, and each of them should be secured to the crosshead by hinges, so that either section or both may be raised when hoisting long material. When using a hoist for transporting long material such as boards, planks, and pipes, the several pieces should be securely fastened together, and the whole Fig. 33. Overhead Covering for the Cage of a Material Hoist. (The cover is made in two parts, hinged together at the center so that tiie\' can be raised when long material must be transported. Note the toe-board and the bar-guards. The tloor of the cage was also provided with blocks for the wheelbarrow legs, though tlie photograph does not show them satisfactorili.) 56 THE TRAVELERS INSURANCE COMPANY Fig. 34. An Iron Stairway, Broken by a Falling Load OF Material. (A load that was being hoisted through this stairway shaft fell and demolished the lower part of the flight here shown. A workman was standing on one of the upper steps at the time, but he fortunately escaped injury.) HOISTING 57 made fast to the hoist in such a way that no part of the load can fall off, or project beyond the sides of the hoist and be caught; and when hoisting this long material to the upper part of the building care should be taken to avoid jamming it into or against the overhead sheaves, or the protective covering over the hoistway. Heavy and massive materials, such as beams and building stones, should be hoisted outside of the buildings when- ever this is feasible, and never through stairway openings. Provide suitable guides or blocks on all hoists upon which wheelbarrows are transported, to hold the barrows securely in place. (See also paragraph 66.) The men should never be allowed to stand or ride on the material hoists; many serious accidents have resulted when this caution has been neglected. Con- tractors and foremen should refrain from riding upon the hoists, not only on account of the danger, but also because it is easy to set a bad example to the men, who can see no reason why they should not ride, if their superiors consider it safe to do so. 31. Hoisting Towers. Under some conditions it is not practicable to install material hoists inside the building, and at some convenient point adjacent to the building a separate, tower-like structure is erected, in which a platform hoist is installed. In many cases where the operations are of considerable size, these towers are erected in duplicate, as shown in Fig. 36. Towers of this kind must be constructed so that they will have the necessary strength and stiffness to sustain all the various stresses to which they may be subjected. Such towers should be built of sound material, and should be designed and erected with careful regard to the maximum loads they may have to carry. They 58 THE TRAVELERS INSURANCE COMPANY should be strongly cross-braced and strutted, and should have exceedingly firm and solid foundations. Great care should also be taken to see that they are made secure against overturning in any direction. With this in view, they should be safely guyed, or strongly anchored to the building itself, or fixed solidly in some other effective way. When used in connection with a high building, they should not be run up to the ultimate height at the outset, because if this is done the problem of keeping them safely in position is often serious, until the framework of the building has risen to a considerable elevation. In such cases it is better to limit the hoist-towers, at first, to an altitude that will suffice for immediate needs, and to extend them upward when the work has proceeded far enough to make it feasible to provide a safe support by bracing their lower parts to the framework of the building. Care should be taken to have all towers of this kind truly straight and vertical, so that the uprights that sustain the loads will not be exposed to bending stresses, and so that the guys or other supports that are provided will not be subjected to stresses of unnecessary severity. In Fig. 36, which shows a pair of material hoists of the kind here under consideration, it will be particularly noticed that the two towers are fastened together in several places, both by horizontal stringers and by diagonal braces. They are also secured to the building at three different heights, by beams that pass in through the window openings in such a manner that they will not interfere with the progress of the work. Hoistways of this kind are often sheathed with boards, and where this is done it is best to cover them on the inside, because a smoother surface is thereby HOISTING 59 Fig. 35. An External Material Hoist. (Under some conditions material hoists are erected outside of buildinys tinder <.onstruction, as shown here.) 60 THE TRAVELERS INSURANCE COMPANY Fig. 36, A Pair of Well-constrcctkd Material Hoists. HOISTING 61 presented to the moving material, and loads are less likely to catch against projections in the hoistways. Long pieces of material, when placed endwise on the cage or platform of a hoist, sometimes give serious trouble in this way; and boxes and other objects that are placed too near the edge of the platform often become displaced so that they catch on the frame- work of the hoistway. The method of sheathing here recommended is seldom followed in practice, the sheath- ing being usually put on the outside of the framework. There is apparently no good reason for doing this, however, except that the hoistway looks a little better from the outside, and that it is somewhat easier to handle the sheathing in putting it on. Aside from the small amount of extra work that may be required in the construction, the only objection that can be offered against placing the sheathing on the inside, as we recommend, is that by so doing it becomes necessary to have the hoistway two or three inches larger, each way. Hoisting towers often have platforms at different levels upon which men must stand or work. All plat- forms of this kind should be ample in size, and they should be closely planked over, and provided with guard-rails, foot-boards, and netting. Safe means of access to these platforms should also be provided. Stairways are greatly to be preferred for this purpose, although runways or ladders may also be satisfactory if they are properly constructed, guarded, and secured. (See also paragraph 61.) 32. Passenger Hoists. In all buildings in which permanent passenger elevators are to be installed, special hoists should be provided as soon as possible, 62 THE TRAVELERS INSURANCE COMPANY for the use of the workmen in the building. This will tend to prevent the workmen from riding on material hoists, and will also save considerable time that would otherwise be spent by the men in climbing ladders and stairs to reach their work. The number of stories to which the construction may advantageously be carried before passenger hoists are installed will de- pend largely upon the height that the finished building is to have. There should be no difficulty in deciding this point in any given case. A regular operator should be provided for each passenger hoist, and an adequate and effective signal- ing system should be installed. The maximum number of persons that may safely ride on a hoist should be determined in each case and specified upon a sign posted conspicuously in the cage; and no greater number than this specified limit should be permitted to step into the cage, under any circumstances. (See Fig. 37.) Dangerous crowding and jostling about the en- trance to the hoist at quitting time may be prevented by making the entrance to the cage so narrow that only one man can be admitted at a time, and by requiring the men to form in a single line and wait their turn. This scheme has been carried out successfully in more than one instance. Except on the sides used for entrance, the cages of all passenger hoists should be completely inclosed to a height of at least six feet, and preferably up to the level of the crossheads; and they should also be covered over on top. The hoistways should also be inclosed, and gates should be installed at the entrances on each floor. Every hoist should also have an effective safety HOISTING 63 Fig. 37. Showing how to Prevent Dangerous Crowding AT AN Elevator Entrance. (With this arrangement only one man can enter the elevator at a time. See also Fig. 38.) 64 THE TRAVELERS INSURANCE COMPANY Fig. 38. Linku Up to Enter the Elevator. (Tliis mcthoil proved effcclive in liandlini; the workmen safely and quickly liI rush hours. See also Fig. 37.) HOISTING 65 Fig. 39. An Approved Method for Protecting a Passen'ger Hoist Shaftway. device that will prevent the cage from falling in case the cable or any other essential part of the mechanism should break. 33. Slings. These form an important part of the hoisting equipment in building construction and every precaution should be taken to see that they are kept in first-class condition. Wire cables, chains, and 66 THE TRAVELERS INSURANCE COMPANY manila ropes are all used for slings, their relative strengths, for similar diameters, varying in the order in which they are here named. For many reasons aside from its strength, a wire-cable sling is to be preferred to a chain, or to a fiber rope of any kind. Ordinarily, deterioration is easily detected in wire cables, because it is commonly indicated by broken strands that are readily discoverable by an experienced and qualified inspector. Chains, on the other hand, may sometimes be used almost up to the moment of failure with no manifest external evidence of weakness other than the existence of a few seemingly unimportant bruises, although a careful microscopic examination will often disclose a multitude of small cracks, show- ing that the metal has become either "fatigued" or strained beyond its yield-point by the severe stresses to which it has been subjected. Wire-cable slings, on account of their pliability, are often bent at very sharp angles, not only while being adjusted to their loads, but also when they are under strain. Sharp bends of this kind should always be carefully avoided, not only because they are imme- diately dangerous, but also because, when taken in connection with the twisting and untwisting to which the strands of the cable are subject while in use, they cause rapid deterioration of the sling. In making a thorough inspection of a wire-cable sling it is advisable to clamp the sling in two places, and partially untwist the intervening section so that the interior wires can be seen and examined. The method of attaching the slings to the load, and to the hook of the hoisting cable, is of great importance and this part of the work should be intrusted only to HOISTING 67 experienced and responsible persons. Loads may often be safely hoisted by the use of a single sling, but in other cases two or three slings are required, — the number to be used depending not only upon the weight of the load but also upon its shape. In placing a sling about a load, it is important to see that the turns of the sling do not lie one over another, because an excessive strain is likely to be thrown upon one of them unless careful attention is given to this point. A sling composed of a single length of wire cable, with spliced eyes, should never be used for hoisting a heavy load by hooking into only one of the eyes, because if this is done there wnll be a tendency for the load to revolve, thus unwinding the cable and permitting the splice to slip. On the other hand, when using a doubled sling with both ends engaged in the hoisting hook, it is important to adjust the sling so as to equalize the stress as well as pos- sible, and prevent it from becoming unduly concen- trated in certain parts. When placing chain slings about loads, carefully avoid twisting the chains, because if they are twisted an excessive load may be thrown upon some of the links. All slings should be kept in good condition. To prevent rusting, chain slings should be frequently oiled, and slings made of wire rope should be treated with oil at proper intervals, or preferably with special protective dressings prepared for this purpose. The inner wires often become corroded through exposure to the weather, even when the outer ones remain in comparatively good condition. The stresses that are thrown upon slings and ropes 68 THE TRAVELERS INSURANCE COMPANY vary a great deal with conditions, and they are often influenced to a marked degree by circumstances which the casual observer might consider trivial and unim- portant. In particular, the inclination or obliquity of the sling, in those parts which lie between the supporting hook and the points at which the sling first touches the load, must be carefully considered, because this is a highly important feature in connec- tion with safety. None of these parts should make an angle of less than 45 degrees with the horizontal. The reason for this will be seen by referring to the accom- panying outline sketches. In order to fix the attention upon the effect that the obliquity of the sling has upon the intensity of the stress, and avoid the necessity of repeatedly qualifying our statements so as to make allowance for the stiffness of wire cables and for other circumstances, we shall Fig. 40. Fig. 41. Fig. 42. Illustrating the Obliquity of Slings. HOISTIXG 69 assume that the sHng is perfectly flexible in all the cases shown in the sketches, and also that the load is sym- metrical in shape and S3^mmetrically supported, and that the branches of the sling (between the hook and the load) are equal in length and equally inclined. For simplicity we shall also assume that the total load that is to be supported is 2,000 pounds in each case. Under these conditions, if the ends of the sling are exactly vertical, as in Fig. 40, the stress on each one of them will evidently be 1,000 pounds. If the ends are inclined, however, as shown in Figs. 41, 42, 43, and 44, the stress upon each of them will be greater than 1,000 pounds in every case, and it will increase as the obliquity of the ends increases, — that is, as they become more and more inclined toward a horizontal position. We shall not undertake to explain this fact fully, because a proper understanding of it calls for a knowledge of the elements of theoretical mechanics, and readers who 11474 "474 Fig. 43. Fig. 44. Illustrating the Obliquity of Slings. 70 THE TRAVELERS INSURANCE COMPANY possess this knowledge will perceive the reason for the increased stress, without explanation. In brief, how- ever, we may say that the stress on each of the inclined ends must have a vertical component equal to 1,000 pounds; and as there must also be a horizontal com- ponent whenever the sling stands obliquely, the total tension in each of the inclined ends must always exceed 1,000 pounds. If the sling is of such a length that its ends, between the hook and the load, are inclined to the horizontal at an angle of 60 degrees, as indicated in Fig. 41, the stress on each end will be 15.5 per cent, greater than it would be if the ends were vertical, as in Fig. 40. That is, in Fig. 41 each end will be subject to a total stress of 1,155 pounds. If the ends of the sling make an angle of 45 degrees with the horizontal, as shown in Fig. 42, the tension on each of them will be 1,414 pounds; and if they lie at a still greater obliquity, so as to make an angle of 30 degrees with the horizontal as shown in Fig. 43, each of them will be subject to a stress of 2,000 pounds. If the obliquity increases still further, the stress will also continue to increase, and in a yet more rapid ratio; and when the ends of the sling approach the horizontal position quite closely, the stress upon them may become very great indeed. For example, if the sling were so short that its ends made an angle of only 5 degrees with the horizontal, as indicated in Fig. 44, each end would have to support a stress of 11,474 pounds. These figures show very clearly the importance of giving careful attention to the inclination of the free ends of the sling. Men engaged in hoisting too often take it for granted that the tension on a sling is HOISTING 71 everywhere the same, and if the sHng is strong enough to support the load in safety when the ends are vertical, they assume that it is safe to hook it around the load in any way whatever. It is plain, from what has been said above, that this is far from being the case. The sling should always be long enough to allow the ends to be at least as steep as shown in Fig. 42; or, in other words, the ends should never make an angle of less than 45 degrees with the ground. The accompanying short table shows the way in which the stress changes in two-part slings, for various inclinations of the ends to the horizontal. The use of the table will be evident, from what has been said above and from the illustrative example that is given below. Effect of THE Obliquity of a Sling. Angle Between Sling and Horizontal STRESS ON SLING, PER POUND OF TOTAL LOAD 5° 5.737 lbs. 10 2.879 15 1.932 20 1.462 30° 1.0000 lb. 45 0.7071 60 0.5774 90 0.5000 Example: Total load, 2,000 pounds. Two-part sling, with ends making an angle of 5° with the hori- zontal. Solution: Opposite 5° in the first column, we find 5.737 in the second column; and multiplying 72 THE TRAVELERS INSURANCE COMPANY this by the total load to be supported, we have 5.737 X 2,000= 11,474 lbs., which, as indicated in Fig. 44, is the stress on each end of the sling. When the load to be lifted has sharp corners or edges, as is often the case with structural steel and other similar objects, pads or wooden protective pieces should be applied at these corners, to prevent the slings from being abraded or otherwise damaged where they come in contact with the load. This is specially important when the slings consist of wire cable or frber rope, though it should also be done even when they are made of chain. To show the importance of protecting sharp corners where slings run over them, reference may be made to Fig. 45. The total load is here supposed to be 2,000 pounds, and as the ends of the two-part sling make an angle of 30 degrees with the horizontal, each of these ends is also subject to a tension of 2,000 pounds. This tension is exerted partly to hold up the load, but it also tends to draw the sling horizontally against the load, at the points indicated by the arrows; and if the sling is pliable, and is placed about the load symmetric- ally as shown in the illustration, it will press against the load, under the assumed conditions, with a horizontal force of 1,732 pounds at each of the upper corners. This pressure may damage either the sling or the load, or both of them; and it is to prevent damage from this source, as well as from the direct weight, that the pads are recommended. Wooden corner-pieces are often provided, as shown in Fig. 46, for use in hoisting loads with sharp angles. If pads of burlap or other soft material are used, they should be thick and heavy enough to sustain the pressure well, and to distribute HOISTING 73 it over a considerable area, instead of allowing it to be concentrated directly at the edges of the object to be lifted. Precautions of this kind are often neglected in the United States, but they receive attention in European practice, and it is to be hoped that their importance will soon be more widely admitted in this country. So far as weight is concerned, loads might often be safely hoisted by the use of single-part wire-cable slings; but in handling structural steel it is customary to use two-part, or "bridle" slings, so that the loads may be properly balanced, and hoisted in a horizontal position. Bridle toggle-slings are also used for simi- lar work, and toggle-column slings are often used for hoisting and setting steel columns. When toggle slings Fig. 45. Illustrating the Pressure of the Sling against the load. Fig. 46. Illustrating the Use of Wooden Corner-pieces. 74 THE TRAVELERS INSURANCE COMPANY are employed it is not necessary for a man to climb up a column or go into other dangerous elevated posi- tions to release the slings, because they can be detached by a man standing upon the ground or the floor. It is advisable to have two complete sets of slings of various sizes constantly on hand, and all slings that are not in use should be stored in a place specially provided for them, and locked up. They should be in charge of an experienced man, who should be held responsible for their condition. The man charged with the care of the slings should give them out as they are needed, and always with due regard to the use to which they are to be put. In this way it is possible to guard effectively against the use of slings of inadequate strength. All slings should be promptly returned to the official custodian, when they are no longer needed for the work for which they were given out. As an addi- tional precaution, every sling should be provided with a small identification tag, which should be firmly fastened to it. The tag should give the maximum stress that the sling can safely withstand in use, and in the case of a chain sling it should also give the date of the latest annealing. V. DERRICKS. 34. Types. The derricks that are most common- ly used in building construction are of the stiff-leg, guy, and breast or house types. Some of these types are subject to slight modifications, and they may then be known by different names; but the general classifica- tion here given is comprehensive enough for ordinary purposes. Each type may be arranged to be operated either by hand or by mechanical means, — the method of operating usually being determined by the weight and quantity of the material to be handled. 35. Stiff-leg Derricks. These are usually em- ployed in excavating for building foundations and for doing other work at or near the ground level, although they are also used to some extent in the more advanced stages of building construction. It is particularly important to see that the timbers that are used in stiff-leg derricks are sound and of adequate size for the work to be performed, and that the several mem- bers are properly jointed and fitted. Selected Oregon fir or yellow pine is most suitable for derrick con- struction. All irons, such as the goose-necks and the connection plates at the heels of the stiff legs, should be of the proper sizes. All bolts should be of the best material, and provided with adequate heads and a sufficient number of threads. Washers should be placed on both ends of the bolts, where necessary, and the nuts should be drawn up tightly. Lock-washers or 76 THE TRAVELERS INSURANCE COMPANY jam nuts should be used, to prevent the nuts from work- ing loose, or the same object may be attained by check- ing the threads on the bolts after the nuts have been tightened. The pins securing the connection plates to the bed sills should be of adequate size, and fitted with cotter pins at both ends. Inspections often show that the connection-plate pins have been lost, and that ordinary bolts, frequently of too small a size, have been substituted. Such a practice should be prohibited. See that the goose-necks are fitted to the stiff- legs in a proper manner, so that there will be no undue friction on the gudgeon pin. If the goose-necks are improperly fitted, or the heels of the stiff-legs are incorrectly set on the bed sills, the holes in the goose- necks will be worn into an elliptical shape, making it more difficult to handle the derrick, and also causing it to jar when the boom is swung around. Further- more, it is quite possible that the gudgeon pin will become so worn that it will fracture and cause an accident. A collar should be placed on the gudgeon pin, above the goose-necks, and a hole should be drilled through this collar and the gudgeon pin, through which a bolt should be passed to hold the collar in position. See that all of the derrick sheaves are of suitable size, that they are secured in place by pins of the proper diameter, and that cotters are placed in both ends of every pin. Pay particular attention to the recess for the sheaves at the end of the boom, because if this is too wide the sheaves will wabble or work along on the pin, and this may cause the cables to run off the sheaves. If the recess is found to be too large, place filler plates on both sides of the sheaves, to make them run true. DERRICKS 77 Fig. 47. Diagram of a Stiff-leg Derrick. (This is simply a diagram for the purpose of showing the names of the various parts of a stiff- leg derrick, and is in no respect a design for a derrick. For a further description of stiff-leg derricks refer to page 75.) 78 THE TRAVELERS INSURANCE COMPANY Fig. 48. Diagram of a Guy Derrick. (See tlic axplanatory note on page 77, in connection with the diagram for a stiff-leg derrick. For convenience, only one gay rope is shown, but in practice there should be at least six, as described on page 81. The boom should fit loosely in its seat, and the pin in the boom seat should never be omitted.) DERRICKS 79 Give particular attention to the weighting of stiff- leg derricks, because this is an item of extreme importance. The necessary weight should be calcu- lated by a competent engineer, in every case. The material used for the weighting should always be in- closed in well-constructed boxes, so that the weights will remain in the proper position and will not be dis- lodged or shifted about by the vibration of the derricks, or in any other way. 36. Guy Derricks. Derricks of this type are used in nearly all of the operations of building construction, and they are made both of timber and of latticed steel. All the guys should be of plow-steel wire of ample strength. These guys should preferably be galvanized, for protection against the weather. The galvanizing should be done to order, however, and ordinary galvaniz- ed cables should not be used. Eyes should be formed in the guys, at the masthead end, by bending back the ends of the cables and clamping the ends with at least three clamps specially designed for the purpose. Place thimbles in these eyes, in all cases, to prevent chafing the cables. Secure the guys to the guy plates by means of shackles, and place cotters in the ends of the shackle pins. Collars should be secured in place above the guy plates in the same manner as recommended for stiff- leg derricks. The way in which guy derricks are anchored will naturally depend upon the location and upon the conditions under which the work is done. When logs buried in the ground (commonly called "dead-men" or "dead-logs") are used for anchorage, they should be placed at a suitable depth, in trenches. After the trenches are filled they should be planked over and 80 THE TRAVELERS INSURANCE COMPANY Fig. 49. Steel Guy Derricks used for Erecting Work. additional weight placed upon them. The weights used for this purpose should preferably consist of well- constructed boxes filled with sand, earth, or stone. The dead-men should be of ample size, and of strong, sound timber. Old blasting logs or limbs of trees are sometimes used, but these should never be trusted unless tliey have been thoroughly inspected before being put in the ground. Inclined trenches should be excavated leading to the dead-men, so that the guys DERRICKS 81 may be placed properly about the centers of the logs, and so that each guy will pull upon its anchorage in as straight a line as possible. In building construction, guy derricks are mainly used for erecting and setting steel, and when they are so employed they must be guyed by some method other than the one described above. Each derrick mast should be provided with at least six equally- spaced guys, and each of these guys should be anchored, by a wire-cable anchor sling, to the columns of the building in course of erection. The bay in which the Fig. 50. Warning Signs Attached to Derrick Guys. 82 THE TRAVELERS INSURANCE COMPANY derrick is to be erected should be fully bolted or (which is far better) fully riveted, and four heavy timbers, each 12 in. by 12 in., or 12 in. by 16 in., should be placed beneath the foot-blocks of the derrick. These timbers should be long enough to extend the entire length of the bay, or from one row of columns to the next. Support- ing bents framed of heavy timbers should be placed beneath the floor system on which the derrick rests, unless the construction is unusually strong. When the span is ten feet or less, and 12-inch or 15-inch beams are used, it may not be necessary to use bents. With a fifteen-foot span and 12-inch or 15-inch beams, one Fk;. 51. Wire-cable Slings Installed for Anchoring Derrick Guys. (Wirn-rope ?linqs arc far better and safer for this purpose than chains Owing to the position of the camera, the apparent steepness of the inclination of tlie nearest guy is nuicli exaggerated in the photograph.) DERRICKS 83 Fig. 52. An Approved Method for Anchoring Derrick Foot-blocks. (Cables are passed around the foot-blocks, as shown. The\' are then crossed, and their ends are made fast to four of the steel columns of the building. For further security cHps are placL-d at the points where the cables cross, as indicated by the arrows. This arrangement prevents the foot-blocks from moving in any direction.) ?4 THE TRAVELERS INSURANCE COMPANY Fi(i. 53. Diagonal Stays for Anchoring the Foot-blocks of Guy Derricks. (This nictliud is al^^o approved. The foot-bio'ks are lashed to tiie floor beams at two points b;.' means of wire rope, in addition to being braced l3y the diagonal sta\'s. T lie dimen- sions of the various tmlbers arc given in Fig. 54.) bent, on the floor immediately below the derrick, should be used. With a fifteen-foot span and beams having a depth of 10 inches or less, supporting bents should be placed beneath the derrick on hvo floors. Each bent should be fastened to the floor immediately above it by DERRICKS 85 Fig. 54. Arrangement of the Diagonal Stays Shown in Fig. 53. means of ropes, and should be made to bear tightly against the beams overhead by driving in double wedges, which should be toe-nailed, or secured in some other manner, so that they cannot work loose and fall out. The foot-blocks should be properly secured, either by timbers or by wire cables; and if cables are used they should be drawn tight by means of steamboat ratchets. Turn-buckles are often used in place of 86 THE TRAVELERS INSURANCE COMPANY steamboat ratchets, but we do not recommend them because the workmen tighten up the turn-buckles by means of bolts or bars, which are often left in position and forgotten, — the result being that they frequently fall out and drop to the lower floors. 37. Breast or House Derricks. In building con- struction, derricks of this type are principally used for setting stone. They are usually operated by hand, and as a rule are not equipped with brakes. Mechan- ical brakes can easily be provided, however, and this should be done in every case. The usual method for braking a breast derrick, when no mechanical brake is provided, is by means of a "bull-tail." This con- sists merely of a length of rope, which is wrapped about the shaft several times; one end is then secured to the frame of the derrick, the other end, or "tail," being held by a workman when lowering a load. By pulling upon the rope sufficient friction may be brought upon the shaft to stop and hold loads of considerable weight. The most efficient bull-tail is made by separating the strands of a 3-strand rope, and braiding them together so as to form a flat surface to bear against the shaft. The men sometimes have their hands and fingers crushed when using these bull-tails, and the rope sometimes breaks and allows the load to drop. For these reasons, among others, we strongly prefer special mechanical brakes, as already explained. A hole should be drilled in each end of the gear shaft, outside of the corresponding handle or operating lever, and a cotter pin should be placed in each hole so that the handle cannot work ofi from the shaft. Accidents often result from neglect of this precaution. Nails, pieces of wire, and other similar objects are some- DERRICKS 87 Fig. 55. A Breast Derrick with Uxprotected Gears. (The gears of breast derricks could be guarded very easily, and mechanical brakes could also be provided with but little trouble. Attention is also called to the dangerous holes just in front of this derrick.) 88 THE TRA\'ELERS INSURANCE COMPANY Fig. 56. A Row of Breast Derricks Used for Setting Stoxe. (These derricks are guyed from the front as well as from the back, as required by good practice. Gear guards and mechanical brakes are lacking, howeyer.j times used in place of cotter pins, but tliis should never be allowed. When lowering loads the handles should always be removed, so that no one can be struck by them. As a rule, breast derricks are guyed from only one direction, and under ordinary circumstances this would be sufficient. When moving the derricks, however, they are straightened up, and are then likely to tip over backward; and the same trouble will occur if a heavy object should drop on the guys, or if the hoisting rope should suddenly break while raising a load. To guard against a possibility of this kind, a front or head guy should be secured to the derrick and to some fixed object on the floor above. If there is no higher floor, DERRICKS 89 Fig. 57. Broken Boom of a Steel Derrick. Owing to the carelessness of the hoisting engineer this boom was lowered until it struck a floor beam at the outer edge of the building. It did not break completely in two but was bent almost at a right angle. Fortunately, the derrick was not loaded at the time ot the accident.) the derrick should be made secure against falling back- ward by some other method. All breast derricks should be set on heavy planks or timbers, of sufficient length to extend from one girder or floor beam to another. They should never be allowed to rest directly upon floor arches, — this counsel being specially important when the arches are newly laid. The base of each derrick should be secured in a suitable manner by means of ropes or cables, or by timber bracing, so that it cannot become displaced. 38. General Precautions in the Use of Derricks. When leaving the work, either for the night or at any other time, it is advisable to lay the derrick booms down, if possible, or to "top them up" (that is, raise 90 THE TRAVELERS INSURANCE COMPANY them into a vertical position). This will prevent the booms from swinging about and fouhng cables or doing other damage, in case of high winds. They should also be secured by guys or otherwise, if the conditions are such that this appears to be necessary or desirable. At least as often as every other day, all parts of every derrick should be inspected, and the moving parts thoroughly lubricated. Special attention should be given to the gudgeon pin at the mast head, and to the bearing at the foot of the mast, for these will wear rapidly if allowed to run dry. Every derrick should be equipped with adequate and effective mechanical brakes, and the brakes should be tested frequently to make sure that they are in good order. All hand- operated derricks should also have suitable ratchets and pawls. The loads should be lowered slowly, and never at a rate of speed exceeding the hoisting speed; when depositing the loads special care should be taken to avoid shocks and jars. Provide substantial and effective guards for all exposed gears, and for all projecting set- screws, keys, and other dangerous moving parts. VI. SCAFFOLDS. 39. Introductory. Only a few general suggestions with regard to scaffolds can be given in this place, because many different types are used, and there is so much to be said about them that an entire volume would be required to treat the subject adequately. The Engineering and Inspection Division of The Travelers Insurance Company has made a special study of scaffolds, however, and has published a large and ex- haustive treatise on the subject. Scaffolds for building construction include the forms used by bricklayers, masons, carpenters, and artisans of certain other classes. The types that are used chiefly by bricklayers and masons may be divided into three main classes which may be designated, ac- cording to their respective natures, as "pole scaffolds," "suspended scaffolds," and "outrigger scaffolds." 40. Pole Scaffolds. Pole scaffolds are by far the commonest of the three types just mentioned. They are of two general kinds: (1) the bricklayers' pole scaffold, and (2) the independent pole scaffold. With the bricklayers' pole scaffold a single row of poles is used and these poles are set solidly on the ground at a distance of not more than 4 ft. 6 ins. from the outer face of the wall. The weight of the platform on which the men stand while at work is supported by ledgers (also called stringers or running strips) which run parallel to the wall of the building and are nailed to the poles, 92 THE TRAVELERS INSURANCE COMPANY SCAFFOLDS 93 VM////M^WM////M///Mmm i%%m;m%%%%%%»m;^%%^^ P O ^^ "« b S.E ta s = <; ( ) "^ '5) in .H c w to "_ ,j o a- , ^ ii( ^J« Z 'T": •g j3 w C 5, Q £" Z^ o < p ,e --->■ » — „o .£ --- X33J 00/ ai33X3 ox XON ,.0 ,S V, 94 THE TRAVELERS INSURANCE COMPANY and by putlogs (colloquially known as putlocks, puds, and spuds). The putlogs run perpendicularly to the wall, and one end of each rests upon a ledger, while the other end is supported by the wall, a brick being omitted from the face course for this purpose, so that the end of the putlog may enter the wall and have a proper bearing. The independent pole scaffold (also called the masons'scaffold) is quite similar to the bricklayers' pole scaffold, with the essential difference that no part of it is supported by the wall. Two rows of poles or uprights are used, one of which sets near the wall, while the other stands far enough away from it to allow a proper space for the platform. Ledgers or running strips are nailed to both sets of poles, but the cross-pieces that run at Fig. 60. A Well-uraced Independent Pole Scaffold. SCAFFOLDS 95 right angles to the wall and support the platform planks are called bearers, bearer-bars, or cross-bars, instead of putlogs. Figs. 58 and 59 show the general arrangement of the bricklayers' pole scaffold and the independent pole scaffold, respectively. Pole scaffolds are often built of utterly unsuitable material, and erected in defiance of constructive principles that would be considered supremely im- portant in a permanent structure. Great care should be given to their design and construction, and a plenti- ful amount of first-class lumber should be used in erecting them. Pole scaffolds often fail for lack of proper bracing, and men often fall from them because guard-rails are omitted or other important safety features are neglected. 41. Suspended Scaffolds. The suspended scaf- fold, as used in construction work and in making repairs and alterations about buildings, consists essen- tially of a platform that is hung from overhead supports (or "thrust-outs") by means of wire cables, and which can be raised with more or less ease as the work pro- ceeds, by winding up the suspension cables so that the bricklayers may always stand at a convenient height with respect to the part of the wall upon which the work is being done. The two types of suspended scaffolds now most generally used differ from each other mainly in the loca- tion of the machines by which the suspension cables are wound up, and in the means by which these machines are operated. With one type, which we shall call the "platform" type, the winding drums and their attachments are secured to the platform itself, and move with it when 96 THE TRAVELERS INSURANCE COMPANY Fic. 61. Suspended Scaffold, with Platform-type Machines. (Tlic scaffolil is raised and liAvi^red Ijy means of llie macliines sliuwn at eitlier cd^e of tlic platform. \Vc remmmcnd a foot-ljoarri alrin^i tlie outer cdfie of (lie platform, in addition di the hand-rail and wire-mesh sereen.) it is raised. These platform machines wind up tlie suspension cables at their lower ends, and are operated from the platforms b}' means of levers or cranks. SCAFFOLDS 97 With the other form of machines, which we shall call the "overhead" type, the drums and their attach- ments are located high overhead and are mounted upon thrust-outs that are secured to the framework of the building. These overhead machines wind up the cables at their upper ends, and are operated from the scaffold platform by means of endless manila ropes running over pulleys or sheaves connected with the drums, and hang- FiG. 62. An Overhead-type Scaffold MAcmNE. (The platform-suspension cables are wound up and unwound by pulling on an endless rope which passes over the grooved pulley at the left-hand end of the machine, — the rope extending down to the platform on which the men work.) ing down freely to the lowest level that the platform will occupy in the course of the work. This brief description, together with the accompany- ing illustrations which show the two types of machines mentioned, will give a general idea of the construction and installation of suspended-scaffold machines. Detail- ed information concerning them is given in the large trea- tise on scaffolds, to which we have previously referred. 98 THE TRAVELERS INSURANCE COMPANY FiG. 63. Supports for Overhead-type Machines. (The ]nachine at the left is in the operating position. Tiie next machine to the right has not been moved to tile operating position at tlie end of tlie ttirust-outs.) We may profitably direct attention to several points that are of particular importance in securing safety in the use of suspended scaffolds. Special attention should be given to the selection and care of the cables used for supporting the platforms. They should be not less than half an inch in diameter, of steel wire, and should have an ultimate tensile strength of not less than five tons. "Standard hoisting rope," galvanized to order, is usually recommended by the builders of scaffold machines, and galvanized cast-steel running rope, out of ordinary stock, should not be used. Particular care should be exercised in securing the ends of the cables; and if the method is employed of SCAFFOLDS 99 fastening the ends into sockets by running in melted metal, the work should be done by an experienced and careful man. The cables and their fastenings should be thoroughly inspected, from time to time, to see that they remain in good condition; and if there is any question whatsoever about their absolute safety, they should be replaced at once. The suspension cables upon scaffold machines of either type are usually from 75 to 100 feet in length, and therefore in the erection of a high building it is necessary to change the position of the thrust-outs to which the upper ends of the suspension cables are secured, every time the height of the wall has increased by approxi- mately one cable length. These shifts should be made with special care, because accidents are quite likely to occur in this part of the work unless it is superintended by a person who understands it thoroughly. The builders of scaffold machines often specify, in leasing them, that they shall be notified when it is necessary to make the shift, so that they can send trained men of their own to supervise the work; and Ave strongly recommend that this be done whenever it is feasible. The men who have to secure or shift the thrust- outs, and particularly those who have to adjust or inspect overhead machines or attach the upper ends of the cables of platform-type machines, must crawl out upon the thrust-outs, and be exposed thereby to death from falling. A stout life-belt should therefore be provided for every man who must go out upon a thrust-out, — the belt being securely attached to a strong, new rope, the end of which should be made fast to some part of the framework of the building (prefer- 100 THE TRAVELERS INSURANCE COMPANY Fig. 64. One of the Hazards Connected with the Use OF Suspended Scaffolds in Building Operations. ably not the thrust-out itself) before the man is permit- ted to go out upon the thrust-out. The rope should only be long enough to enable the man to do his work without inconvenience; because if there is a needless amount of slack, the fall of the man would subject the rope to a snapping stress of unnecessary severity, and it would be more likely to break than it would be if it were shorter. (See also paragraph 68.) No man should be permitted to go out upon a thrust-out, except for some definite object the attain- ment of which appears to be worth the chances that are involved; and even in this case no one should be per- mitted to do so except the man or men designated SCAFFOLDS 101 Fig. 65. A Well-constructed Outrigger Scaffold. for the purpose by the foreman in charge of the work. 42. Outrigger Scaffolds. In scaffolds of this kind the characteristic and essential feature is the support of the platform by outwardly-projecting beams (called "thrust-outs," "outriggers," "jibs," "cantilevers," "bearers," and various other names), that are supported in some safe way, — preferably by framework and bracing, inside of the building. The platform is either laid directly upon the thrust-outs, or supported from them immediately and without the intervention of any considerable space or sustaining mechanism. (The suspended scaffolds described in the previous section 102 THE TRAVELERS INSURANCE COMPANY are not usually classed as outrigger scaffolds, because although they are supported by beams that are thrust out from the building, they are of such a special design that they constitute a class by themselves.) The sustaining beams of an outrigger scaffold should always project entirely through openings in the wall, or through windows, and be solidly and properly supported and braced on the inside of the building. Ex- ternal struts and braces should be used whenever they may be needed to provide additional strength and stiffness. The thrust-outs should be rigidly held, so that no displacement of them will be possible, in any direction. They should be of the best material obtainable, and should be strong enough, when considered as beams supported at one end, to sustain, with a factor of safety of at least ten, the heaviest load to which they will be subjected. 43. Horse Scaffolds. These are used for many purposes, both in demolition and in construction work. They should always be of substantial construction, and should rest upon a firm and level foundation. They should never be erected so that they rest upon beams alone, but should always stand upon solid floors. If the permanent floor-covering has not been installed, a temporary layer of planks should be placed upon the beams to support the horses. Sound, strong material should be used when extending the legs of horse scaf- folds. The work should be carefully done, and the legs should be braced near the joints to stiffen them. It is always far better, however, to use horses of special construction, rather than to extend the legs of existing ones for the purpose of attaining the necessary height. SCAFFOLDS 103 Piles of brick, stone, or other loose material should never be used by the workmen in place of scaffolds or platforms, nor should scaffolds, platforms, or horses rest upon such piles, or be supported by them. All horses should be solid in construction, and of good design. (See Fig. 67.) They should be made of sound, selected material, and should be braced in- ternally so as to be rigid enough not only to carry their normal vertical load with safety, but also to resist deformation from sidewise thrusts. Horses, the parts of which have become loosened or weakened in any way whatsoever, should not be used until they have Fig. 66. A D.\ngerous Method of Sfpforting a Horse Scaffold. (The horses should always rest solidly upon the floor, and should neyer be blocked up in this way, upon tiles or other insecure objects. The floor conditions here shown are also unsatis- factory. Waste material should neyer be allowed to accumulate in such large quantities.) 104 THE TRAVELERS INSURANCE COMPANY been repaired in a thorough and workmanlike manner; and extensive repairs should not be undertaken, because it is much better to discard a horse altogether, and replace it with a new and sound one, than it is to spend an unreasonable amount of time in patching up one that is old and weakened. Horse scaffolds are less suitable for exterior work than for operations inside of buildings. Many contrac- tors, however, use them for outside work, and some- times build them up to a height of six or eight tiers. We strongly recommend some other form of scaffold Fig. 67. A Well-designed Horse. SCAFFOLDS 105 Fig. 68. Remains of a Horse Scaffold, after it had been Fouled by a Hoisting Cable. 106 THE TRAVELERS INSURANCE COMPANY in cases like this, because the horse scaffold is by nature less solid and stable than other types that can easily be had. If it is used in such cases, it should be con- structed with great care, and on all scafifolds more than two tiers high the legs of the horses should be nailed down sufficiently to prevent any horse from shifting as the result of wind pressure, the thrust of ladders, the accumulated effect of repeated small motions, or other causes. 44. Riveters' Scaffolds. The scaffolds used by riveters are moved about so frequently that it is hardly feasible to safeguard them as completely as other types. Guard-rails should be provided whenever practicable, however, and every other precaution should be taken to avoid accidents. Only sound, strong planks should be used for the platforms, and they should be laid so that they cannot tip or slide. Special care should be exercised in selecting the needle-beams for scaffolds of this kind, and they should be inspected frequently to make sure that they are in good condition. When it is necessary to use a scaffold of this nature in such a position that one needle-beam is considerably higher than the other one, the planks should be pro- vided with cleats to insure a good foot-hold for the men, and each plank should also be pierced, about one foot from each end, with a hole about "'s of an inch in diameter, through which a loosely-fitting bolt should be passed. These bolts should be provided with nuts so they cannot drop out when the planks are turned over, and in laying the platform of the scaffold the bolts should come outside oi the needle-beams in all cases. 45. Painters' Scaffolds. The light, swinging scaffolds that are used for painting should preferably SCAFFOLDS 107 be secured to the building at all times, so that they cannot swing materially in any direction. They should always have guard-rails on the side away from the building, at least. In a number of cases, however, men have fallen between the scaffolds and the walls of buildings, and it is therefore better to have guard- rails on both sides of the scaffolds, as shown in Fig. 70. (If the scaffolds were always secured to the buildings, as recommended above, so that they could not swing. (O)*^ FOR >\// SUSPENSION Fig. 69. A Painters' Scaffold with a Single Guard-rail. the guard-rails on the outer side might be sufficient; unfortunately, however, this precaution is often neg- lected, and in such cases the additional rails would furnish the necessary protection.) Painters' scaffolds and other light, swinging scaf- folds that are supported by ropes, should be carefully tested, immediately before using, by raising them a foot or so from the ground and loading them with 108 THE TRAVELERS INSURANCE COMPANY GUARP RAILS Fig. 70. A Painters' Scaffold with Guard-rails on both Sides. a weight at least four times as great as the maximum load they may have to support while in use. The ropes of all such scaffolds should also be carefully protected from contact with acids and other chemicals, and should be tested from time to time to see that their strength remains unimpaired. Scaffolds of the types here under consideration should always be lowered to the ground, or lashed, when leaving the work for the night. All tools and materials should likewise be removed from such scaffolds when the men are not at work upon them. 46. In General. Except in certain special cases where the working conditions make the adoption of such SCAFFOLDS 109 Fig. 71. Machine for Use with Painters' Scaffolds. (The illustration shows a comparison between a scaffold machine and the blocli and falls ordinarily used with licht, swinging scaffolds. When the machine is used there is no danger of accidents due to the slipping of an improperly-made hitch or knot, and there are no dangling rope ends which may be fouled and pull the scaffold down. These machines are also recom- mended for use when cleaning down walls. Their steel cables do not dangle below the plat- form, but are well protected from the cleaning acid.) safeguards impracticable, scaffolds should be provided with hand-rails, and also with toe-boards to prevent ma- terials or tools from falling over the edges of the plat- forms. In addition, wire-mesh side screens are strongly recommended; and whenever scaffolds are located so that there is a considerable height over them from which materials and tools might be dropped, they should also be provided with efficient overhead guards of planking, wire netting, or some other effective sub- stitute. It is common indeed to see the hand-rails, toe-boards, side screens, and overhead protection 110 THE TRAVELERS INSURANCE COMPANY Fig. 72. A Study in Dangerous Scaffolding. (This scaffold is constructed in an ingenious way, but its only otlicr merit is tliat it is bad enouuli to beinterestinK as well as dangerous. Tlie main platform, whieli can be seen at the top of the picture, was about 35 feet above tlie grountl. Note the bend in tlie plank support- i n rr tht^ llnnrT K-irrrilc 1 the upper barrels.) entirely omitted from scaffolds, and many of the scaffold accidents that occur are due to these omissions. The planks forming the platforms of scaffolds should be laid tightly together, so that there will be SCAFFOLDS 111 no chance for tools or materials to fall down between them. The planks or boards forming the platforms should also be placed so that they cannot tip up under the weight of a workman, at any point whatever. Scaffold platforms should not be used for the storage of materials, except such as are immediately required by the workmen; and they should be kept as free as possible from obstructions, so that the work- men may move about upon them in safety. Accumu- lations of snow and ice should be promptly removed, and when the platforms become slippery they should be liberally sprinkled with sand or ashes. If heavy stonework must be handled on scaffolds, extra reinforcement should be provided wherever neces- sary, to make the scaffolds safe under the unusual loads. Men should preferably be kept away from places directly under scaffolds, whether these are outside or inside of the building. Under some conditions, how- ever, this course is impracticable; and when men must work on or beneath scaffolds where there is danger from falling objects (as, for example, in elevator hoist- ways, ventilating shafts, and other similar places) substantial protective coverings should be installed above or below the scaffolds, as may be necessary, to guard all the exposed men against injury. Doorways and passageways, where men have to pass under a scaffold or under some other place where construction work is going on, should be effectively covered with roofs or sheds. Mortar beds are often placed almost immediately under scaffolds. If they cannot be placed elsewhere, they should be protected by substantial roofs. In building a scaffold of any kind, always use 112 THE TRAVELERS INSURANCE COMPANY Strong, first-class material, and plenty of it. Further- more, be sure the scaffold is rigid as well as strong, so that it will not yield or shake when the men move about upon it, nor when portions of the load that it has to support are shifted; and never intrust the building of such a structure to anybody but a responsible man who knows what ought to be done, and who is willing to do it. Every man who has to make use of a scaffold should be required to satisfy himself of its safety before he ventures out upon it. All scaffolds, stagings, and other similar temporary structures should be removed as soon as the need for them ceases to exist. VII. LADDERS, STAIRWAYS, AND RUNWAYS. 47. Ladders. As fast as the work progresses, safe means should be provided to give access to all points in the building. For this purpose numerous lad- ders are necessary, and as too little attention is given, in general practice, to making them strong and sub- stantial, many accidents result. Ladder manufacturers are giving increased attention to this matter, but crude ladders are often made up by the men on the job from any material that is at hand, — cross-pieces being nailed to a pair of stringers of the necessary length, with little regard to the proper strength and spacing of the cross- pieces, or the ultimate safety of the finished structure. The stringers and rungs are often rough and full of slivers and splinters, and projecting nails are also common. The workmen have to go up and down these ladders many times a day, and they are subjected to great and wholly needless danger because of the poor construction. (If temporary cleat ladders must be used, they should be constructed in accordance with the specifications given on page 114.) Every ladder should be strong and substantial, composed of the best materials obtainable, and con- structed with great care. For manufactured ladders the stringers should be of spruce, Oregon fir, or selected yellow pine, and the rungs or cross-pieces should be of oak, white ash, maple, or hickory. Special attention should be given to all ladders that are used for connect- 114 THE TRAVELERS INSURANCE COMPANY I Builders' Portable Cleat Ladder APPROVED CONSTRUCTION LENGTH Inside Width Bottom Top Cro5s Section of Rails Cross Section of Cleat 10'0"tol2'0" 20" 17" 2 "x4" rx3" 13'0"tol6'0" 21" 18" 2 "xi" r'x3" 17'0"to20'0" 23" 20" 2|"x5" I"x4" 2l'0"to24.'0" 20" 23" 21 "x 5" I"x4" 25'0" to 30'0" 28" 24." 3 "x6" r'x4" Rails should be of straight-grained, sound spruce, Oregon pine, Norway pine, yellow pine, or other wood of equal strength. Cleats should be of straight-grained, sound spruce, yellow pine, or other wood of equal strength. Cleats should be housed into rails i inch, and should be nailed to each rail with three ten-penny wire nails. Sound knots will be permitted in rails and cleats when they do not exceed -|- inch in diameter and are \- inch or more from edges of rails and cleats. Cleats should be spaced 12 inches apart from center to center on all ladders. Claat Note — These specifications apply to ladders that are built by con- tractors for temporary use. It is not intended that ladders of this type shall be recommended in preference to manufactured lad- ders. Fig. 73. LADDERS, STAIRWAYS, AND RUNWAYS 115 ing the various floor levels prior to the installation of the regular stairways. These ladders should be set in place immediately after each rise of the derrick, and they should not be removed until the stairways are in proper condition for use. On large construction jobs, ladders used for this purpose may be made double the width of an ordinary ladder, with an extra stringer in the center. (A ladder of this kind may be seen in Fig. 84.) Preferably, however, there should be two sep- arate ladders, side by side, — one to be used for ascend- ing and the other for descending. Provide suitable landing platforms at the upper and lower ends of these ladders, and at all other points where the workmen must step on or off them; and see that each lad- der is long enough to extend at least 5 feet above the highest platform, to enable the workmen to grasp it firmly before descending. In installing a ladder for any purpose, it is advisable to have one of its rungs come flush with the platform to which the ladder leads. When this is not practicable, care should be taken to have the rung that is nearest the platform stand two or three inches above it, rather than below it, because a better footing can be had in this way. See that every ladder is securely fastened both at the top and at the bottom, so that it cannot move in any direction; and if necessary, it should also be braced at the middle of its length to prevent it from swaying, bending, or shaking. Do not permit tools or other objects to be left upon the landing platforms. Take care to place all portable ladders on a firm and level foundation, and see that they are so placed that they can neither tip over, nor slide sidewise, nor slip at the bottom. Ladders should be equipped with 116 THE TRAVELERS INSURANCE COMPANY Fig. 74. A Poorly-constructed Ladder. (Similar ladders are often found on construcfion jobs, and they cause many accidents. In tliis case the danger was also increased by maintaining a bright, open fire close to the foot of the ladder.) LADDERS, STAIRWAYS, AND RUNWAYS 117 safety pads or shoes, or with spurs, whenever they rest upon any material on which they are likely to slip. The shoes may be made of some abrasive substance, or of rubber or other suitable material. Sharp metallic spurs are effective when the ladder rests upon a surface that these spurs can penetrate. Inspect all ladders frequently, replace all worn or missing rungs, and make all other repairs that may be necessary. Ladders up which materials are to be transported should not be more than 30 or 35 feet in length. If it is necessary to proceed to a greater height than this, two or more separate ladders should be used; but in such a case the successive ladders should not come one over another, and no one of them should extend over a place where men are at work, nor over any passageway. If such an arrangement is impracticable, each ladder should be sheathed underneath in such a way that objects falling from it will be arrested by the sheathing, and prevented from falling upon the ladders or workplaces below, — the sheathing being placed far enough from the under surface of the ladder to insure a good foothold for the men, upon the rungs. Helpers carrying material in hods or otherwise should be in- structed not to go upon a ladder when another man is already upon it. Serious accidents frequently occur when this precaution is neglected, because it is not uncommon, when two men are using a ladder at the same time, for the upper one to fall or to drop his load or some part of it, thereby knocking the lower man from the ladder. It is best to have at least two ladderways, one to be used exclusively by men going up, and the other exclusively by men going down. When this plan is in force it is easier to make the men 118 THE TRAVELERS INSURANCE COMPANY go up one at a time; because when a single ladderway is used for travel in both directions, they naturally form the habit of ascending with their loads, in gangs or groups of three, four, or five, in order to avoid con- fusion and delay through meeting others who wish to come down. Workmen using ladders should not be permitted to carry loads that will interfere with the free use of both hands for holding on to the side-bars. Sliding down ladders should be forbidden, and the men should always face a ladder when ascending or descending it. Except in case of real necessity, ladders should never be extended by joining two of them together. It is far better, whenever practicable, to arrange them in single lengths with a landing platform at the top of each ladder. Whenever it becomes necessary, for any reason, to join ladders together, the operation should be performed with great care, by a person skilled in the work; and the joint should be solidly braced and supported, so that no bending stress can be thrown upon it. 48. Stairways. The stairways should be installed as rapidly as the progress of the work will permit, — temporary stairways being installed in preference to ladders, whenever practicable. Stairway openings should be effectively guarded by toe-boards, and all treads, risers, and railings, whether permanent or tem- porary, should be of sound, strong material, firmly secured in place. No openings should be left through which objects of any kind may fall, and the stairs should be kept free from bolts, nuts, rivets, small pieces of brick or tile, and other similar objects that might cause the men to fall. Storing material on stairways should be LADDERS, STAIRWAYS, AND RUNWAYS 119 Fig. 75. A Dangerots Stairway. (A single plank takes the pkire of the stair-landing. A condition of this kind should never bi Iiermitted to exist ) 120 THE TRAVELERS INSURANCE COMPANY Strictly prohibited, and an earnest effort should be made to keep every stairway entirely free from obstructions, so that a safe passage will be assured. To prevent falls that might be caused by tripping, install a suitable plat- form or landing wherever a riser at the top of the stair- way projects above the floor arches or the temporary floor levels. Be sure that ample light is provided on all stairways during the entire working period. 49. Runways. All runways should be substan- tially constructed, and effectively braced or otherwise supported, to prevent bending, swaying, or vibration. Single-plank runways for wheelbarrows should not be used. It is far better to make the runways at least Fig A Dangerous Condition on a Stairway, (This condition is common in buildings under construction. Fig. 77 shows how it may be remedied.) LADDERS, STAIRWAYS, AND RUNWAYS 121 three planks wide, because this gives a sufficient width for most purposes, and it also affords a good track for the wheel of the barrow, which then has a full plank for its support instead of having to travel along a crack, as is the case when two planks are used. Run- ways on which wheelbarrows or trucks have to pass one another should consist of from five to seven planks. All runways that are four feet or more above the ground should be provided with substantial hand- rails, and cleats should be nailed to them, whenever necessary, to afford a firm footing for the workmen. A clear space of moderate width, free from cleats, may be left in the center, if necessary, for the wheels of the Fig. 77. Temporary Treads for a Stairw.w. (These treads at the bottom of the stairs at the left, and the top of the stairs at the right, remedy the dangerous condition shown in Fig. 76.) 122 THE TRAVELERS INSURANCE COMPANY Fig. 78. A Stairway which Invites Accidents. ((")bserve the absence of hanci-rails on the stairway in the background of the illustration. In addition, one or two treads are missing. Directly in front of the stairway is an unguarded hoistway opening, and the stair well at the right is entirely unprotected.) barrows. Runways that are six feet or more above the ground should also have foot-boards along their sides. See that all runways are kept free from projecting nails and screws, and also from slivers and splinters. Sand, stone, and other materials which would interfere with the free movement of wheelbarrows on the run- ways, should be removed as often as may be necessary. If the planks of the runway are laid so that they lap over each other, a beveled piece of wood, running cross- wise with respect to the runway, should be fastened against the ends of the overlapping planks. The piece so used should be at least nine inches wide, and it should be of the same thickness as the planks on one side, and be thinned down nearly to an edge on the other side. If the planks of the runways are laid flush with one another for the purpose of avoiding overlapping, the supports upon which they abut must be of ample LADDERS, STAIRWAYS, AND RUNWAYS 12o Fig 79. A Steep Single-plank Runway. (Below it. on all sides, are boards and miscellaneous pieces of lumber with projecting nails. Jn the background is a pile of fine, dry sand which was blown about by the wind, and often into the eyes of workmen in the vicinity.) width to insure safety, and in such cases it is also important to nail the planks firmly to the cross-pieces upon which they rest. VIII. STEELWORKERS. 50. Erecting Gangs. The work of erecting the steel framework of a large building is extremely hazard- ous, and there is little that can be done to safeguard the men in some of the operations. Dependence must mainly be placed, in such cases, upon the caution, skill, and good judgment of the men themselves. They should never be allowed to expose themselves to danger unnecessarily, nor to ride upon loads, nor on the hooks, cables, or slings of the hoisting apparatus, nor to slide down ropes or cables. Proper ladders should be used for giving access to the work, wherever possible, and the men should not climb up nor slide down on col- umns. Work should be discontinued during severe storms and high winds, and also when the steelwork is slippery from ice or frost; and the men should not be allowed to work in exposed places more than a reasonable number of hours, nor to become unduly fatigued. Steelworkers should avoid wearing shoes with the soles and heels nailed on, because nails are likely to cause the men to slip when walking about on the steel beams. Leather shoes with rubber soles and heels are recommended. It is an almost universal custom among steel-erectors to wear gloves while at their work, and many cuts and bruises on the hands are thus prevented. The gloves should not have stiff gauntlets, however, and it is better to avoid gauntlets altogether, because STEELWORKERS 125 Fig. 80. Steelmen being Lifted to tkeir Work. (This practice is dangerous, and wholly unnecessary. Many engineers consider it safer to raise the men in this way tlian to have them chmb the columns; but the use of suitable ladders is far safer than either of these methods.) 126 THE TRAVELERS INSURANCE COMPANY they may catch upon projections, and thereby cause the men to lose their balance. They may also catch upon tools that are lying about, and cause the tools to fall. Riveters and heaters need the protection afforded by gauntlets, to prevent burns on the lower parts of the arms caused by hot scale and sparks. The foregoing rule does not apply to these men, therefore; but the men should be mindful of the increased possibility of accidents due to the wearing of gauntlets, and should exercise correspondingly greater care. 51. Erecting Floors. Cover over the erecting floor tightly so that there will be no openings left through which tools, bolts, rivets, or other small objects may fall. The men should not leave drift pins, dollies, wrenches, or other objects lying on beams or in other elevated positions. (See also paragraph 63.) When leaving the work care should be taken to secure all objects, or to place them where they cannot be disturbed by the wind. Rivet-heating forges should re- ceive attention in this respect, and empty rivet kegs, paint pots, and other similar objects should be safely stowed. 52. Rivet-heaters' Platforms. Lack of care is often noticeable in the location and erection of the platforms for rivet-heaters' forges. These platforms should be at least 13 feet long and 8 feet wide, should be provided with toe-boards, and should be located as near as possible to the point where the riveting is being done. The planks should also be laid closely together, so that nothing can fall between them. 53. Throwing Rivets. Rivets should never be thrown across shaftways or toward the outside of a STEELWORKERS 127 Fig. 81. A Workman Taking Unnecessary Chances. fPhotograph bj' Brown Brother?.) building. When riveting is being done on an outside wall the rivets should be passed by hand or should be thrown as nearly as possible in a direction parallel to the wall. Buckets with flaring sides are not recom- mended for catching rivets, because the rivets are more likely to bound out of them than out of buckets or cans with straight sides. If metal buckets, pails, or cans are used, false bottoms of soft wood should be placed in them, to prevent the rivets from rebounding. It is often possible to pass rivets for considerable distances through suitably-arranged iron pipes, and this should be done, if feasible, whenever the forges are located some distance away from, and above, the place 128 THE TRAVELERS INSURANCE COMPANY where the riveting is being done. (See also paragraph 44.) 54. Pneumatic Hammers. The snaps and plung- ers of pneumatic riveting hammers sometimes drop out, and they may even fly out with considerable force, and injure persons. To prevent this, one end of a piece of No. 8 annealed iron wire should be secured around the snap and the other end around the handle of the hammer, in such a way that there will be suffi- cient slack to permit the hammer to operate properly, but not enough to allow the snap to drop out of place. 55. Care of Air Hose. Riveters should care- fully avoid allowing the air hose to become wrapped about their legs or other parts of their bodies, because it is likely to twist and turn, and may cause them to lose their balance and fall. The playing of so-called "practical jokes" with compressed air should be abso- lutely forbidden, because severe injuries are often caused in this way. 56. Handling Structural Steel. When hoisting a load of structural steel from the street, a rope should be attached to it by which a man stationed on the street may guide the load until it reaches the level at which the steel is to be erected. The load should then be "boomed over," and one or more men on the erecting floor should take hold of the guide rope and pull the load into the proper position. In this way it is possible to avoid, in large measure, the danger to which steel- workers are exposed when they have to push or pull the loads into position while standing on narrow beams, or in other places where the footing is insecure. IX. MIXING AND POURING CONCRETE. 57. In General. There are a number of different ways of mixing and pouring concrete, and the method employed in any particular case depends largely upon the size and character of the job. The simplest way, of course, is to mix the materials by shoveling them over by hand, after which the concrete is either shoveled directly into the forms, or is transferred in wheelbarrows from the point where it is mixed to the place where it is poured. This method is slow and inefficient and is seldom employed on large operations. It is commend- able from the safety engineer's viewpoint, however, because with hand-mixing the possibility of serious accidents is reduced to a minimum. 58. Mechanical Mixers and Their Hazards. Me- chanical mixers are now available in a large variety of types, adapted to jobs of every size and description. Many of these are portable or semi-portable, and are mounted either on wheels or on skids so that they may be moved about (some of them are self-propelled), as convenience requires, to various parts of a particular job or from one job to another. The motive power for operating concrete mixers is furnished by steam or gasoline engines or electric motors, and the mixer and the engine or motor are usually mounted on the same base so that they form a complete unit. It is to be regretted that so little attention is given to the mechanical hazards of concrete mixers, partic- 130 THE TRAVELERS INSURANCE COMPANY ularly in connection with mixers of tlie smaller sizes. Guards for the exposed gears, belts, sprockets and chains, flywheels, and other moving parts of the machines are the exception rather than the rule. Pro- jecting set-screws are quite common, and they are always dangerous. All of these moving parts are acci- Fk;. 82. Guards for a Concrete Mixer. (TliL- circular shcct-rnetal cover at about the middle of tlie illustration is ;i RUard for the engine tlywlK-el. Hack of it is another sheet- metal guard for tlie gears that drive the mixer.) dent-producers which might be eliminated with com- paratively little trouble or expense. As an illustration of the seriousness of the accidents that may result from lack of safety precautions in connection with concrete mixers, we may mention a case where a man's coat was caught by a set-screw on a gasoline engine driving a mixer. The man was unable to release himself and MIXING AND POURING CONCRETE 131 was drawn against the unguarded gears of the mixer. His chest and right shoulder were crushed and he died almost immediately. The hoppers or "skips" on large portable mixers of some types are also sources of danger. With the ar- rangement that we have in mind a sheet-metal hopper, Fig. 83. A Large Self-propelled Concrete Mixer. '^^'^Jrkmen are sometimes struck and injured by the hopper, as it is lowered to the Rround, and it is therefore advisable to paint a conspicuous warning sign on it, and to install an automatic alarm gong on it. This illustration shtnvs road-making operations. Similar concrete mixers are used on building-construction work.) hinged at the end nearer the mixer, is lowered to the ground and the stone, sand, and cement are deposited on it. When the hopper is full the outer end is raised by means of a hoisting device which forms a part of the machine, and the contents of the hopper slide into the 132 THE TRAVELERS INSURANCE COMPANY mixing drum. The special danger to which we refer is the possibility of the men working about the mixer being struck by the hopper when it is lowered. Acci- dents of this kind occur from time to time, and in one case a prominent New York contractor was killed in just this way. Some manufacturers of concrete mixers provide guard-rails which may be placed on either side of the skip, at the base of the machine, which prevent persons from walking under the skip while it is raised. Unfortunately, however, the men in charge of the mixers often fail to use these guards when they are provided. The neglect of such a simple pre- caution is inexcusable. In the absence of guard-rails it is advisable to pro- vide the mixer with a gong, which will be automatically sounded by the mechanism that releases the hopper. It is also advisable to paint a conspicuous danger sign on the bottom of the hopper, warning persons to keep at a safe distance; and the operator of the mixer should invariably see that all the workmen are out of the danger zone before the hopper is lowered. 59. Wheelbarrows and Runways. Wheelbarrows are used for transporting the concrete from the portable mixers to the points where it is to be poured. There are a number of hazards in this part of the work that are too often overlooked or neglected. In the first place, the wheelbarrows should be kept in good condi- tion. If they are constructed of wood, care should be taken to see that there are no splinters in any part of the barrows, that might cause injuries. Metal barrows are more commonly used, and these should also be examined from time to time to discover defects or weaknesses. (See also paragraph 66.) MIXING AND POURING CONCRETE 133 Elevated and inclined runways are required, on many building jobs, to make it possible for the loaded wheelbarrows to reach the points where the concrete is to be poured. The use of these runways may lead to accidents, unless they are constructed carefully and with sufficient strength, and are maintained in good condition. The suggestions contained in paragraph 49 should be carefully followed, in order to make the use of runways as safe as possible. 60. Storing and Handling Sand and Stone. The methods of handling concrete just described are those commonly employed on operations of comparatively small size, where the concrete work can be finished in the course of a few days, or, at most, in a few weeks. The equipment is often of a more permanent character, however, and the methods employed are somewhat different, when constructing the walls and floors of large buildings. We shall not attempt to describe all these methods, but shall confine our attention to two of them which are fairly typical. The distribution of the concrete mixture is accomplished in the same manner in both cases, but the methods of delivering the sand and stone to the mixer are somewhat different. In one case sand and crushed stone are delivered by truck, trolley, train, or other means, at a convenient place outside of the actual zone of building operations, and are stored in piles where they will not interfere with the work. Tracks are laid on an incline from the storage area to a platform over the concrete mixer, which is situated nearer the work. A cable-drawn "skip" or car, divided into two compartments of proper size, brings the sand and stone in the correct proportion to the mixer platform, and dumps these materials into 134 THE TRAVELERS INSURANCE COMPANY a hopper which dehvers them to the mixer, — the cement and water being added at the same time. In the other system a large bin is erected over the mixer. This bin is divided into two parts, — one for the sand and the other for the crushed stone. The sand and stone are brought to the job by trucks or by some other means, and are dumped on the ground on either side of the bin. They are there elevated and deposited in the bin by a clam-shell bucket operated by a derrick. The derrick boom is raised high enough to clear the bin and is maintained at this elevation, so that the movements of the derrick are confined to swinging the boom and hoisting and lowering the bucket. As in the method last described, a platform is erected directly above the mixer, and the sand and stone are delivered to this platform, by chutes leading from the lower part of the bin and thence downward through openings in the floor of the platform to the mixer. The flow of sand and stone is regulated by gates placed in the chutes. The danger from exposed gears, belts, sprockets and chains, and other moving parts of the mixers, is considerably diminished when using either of these two systems, because most of the work is done on the platforms above the mixers. The machines must be oiled regularly, however, and attention of other kinds is often necessary, so none of the danger points should be left unprotected. The elevated platforms should be guarded by substantial railings, and the men should be cautioned to use all possible care to avoid stepping or falling into the openings in the platforms through which the materials are delivered to the mixers. Careful and experienced men are required for MIXING AND POURING CONCRETE 1,?5 handling the motors or engines used for hauling the skips or operating the derricks. The exposed moving parts of the motors or engines should be guarded, and all ropes and cables should be inspected frequently and kept in good condition. At least six equally-spaced guys should be pro- vided for every guy derrick, and particular attention should be given to the fastenings of these guys. Every derrick should be equipped with adequate and effective mechanical brakes, and the brakes should be tested frequently to make sure that they are in good order. (See also section V, with regard to the care and opera- tion of derricks.) 61. Concrete Towers and Distributing Chutes. With both the "skip" and the "bin" arrangements, just described, the method of delivering the mixed concrete to the forms is the same. A tower is erected in which a bucket travels, — the bucket being hoisted by an engine or motor. The mixer empties directly into the bucket, which when full is hoisted to the top of the tower, where the contents are discharged through a hopper into an inclined metal chute. This chute extends from the tower to the point where the concrete is to be poured, and the concrete slides down through the chute by gravity. Sections are added to the chute as the distance from the mixer to the delivery point increases, and the most distant section is arranged to swing horizontally so that a considerable area may be taken care of without shifting any other part of the equipment. (Fig. 84 shows a distributing arrangement of this kind.) Some of the precautions that are necessary to insure safety in connection with concrete-hoisting towers are as follows: Every tower should be substantially 136 THE TRAVELERS INSURANCE COMPANY MIXING AND POURING CONCRETE 137 constructed of sound and suitable material. (See also paragraph 31.) In many cases the towers are of wood and are erected on the job. The various parts should be bolted or spiked together with as much care as if the structure were to be a permanent one, and the complet- ed tower should be thoroughly inspected before using it. Steel towers are also used, and are stronger and more substantial than those of wood. They are constructed in sections which may be bolted together to form com- pleted towers of any required height. Steel towers must also be erected with great care, and should be painted to prevent rusting. Each tower should be securely guyed to prevent overturning. Two sets of guys at different elevations are quite commonly provided, and if a tower is unusu- ally high, three sets or even more may be required. The guide rails for the bucket should be carefully alined, and care should be taken to keep them in good condi- tion so that the bucket cannot become caught while being hoisted. The sheaves over which the cable passes should be firmly secured and should be kept well lubricated. See that the hoisting cable is free from broken wires and other defects, and treat it from time to time with a suitable preservative dressing. Provide a substantial railing about the platform near the top of the tower, where concrete is dumped from the bucket into the chute, and construct or erect a strong ladder on one side of the tower, to enable the attendant to reach this platform in safety. See that the attendant uses this ladder, and that he never rides up to the platform in the bucket. Our attention has been drawn to a number of serious accidents that have resulted from riding in a bucket in this way. The rider 138 THE TRAVELERS INSURANCE COMPANY often grasps the hoisting cable, and his fingers are likely to be crushed by being drawn into the sheave or pulley at the top of the bucket. In one of the accidents to which we refer, the man had to have three fingers amputated in consequence of having them caught in this way. The metal chutes through which the concrete is distributed become stopped up occasionally, owing to the use of too dry a mixture or to lack of care in cleaning the chutes at the end of the day's work. It then be- comes necessary to send a man up to remove the ob- struction. There is a considerable element of danger in this operation (due to the possibility of falling), against which there appears to be no efi'ective and easily- adopted method of protection. A careful man should be assigned to this task — preferably a rigger who is accustomed to working at high elevations — and the necessity for caution should be further impressed upon him by the foreman on the job. To prevent stoppages of this kind in the chutes, plenty of water should be used in mixing the concrete. A small amount of slaked lime is soinetimes added to the mixture for the same purpose, because this tends to make the concrete slide easily. The chutes should be thoroughly flushed out with water at the end of each run, in order to make them as clean as possible, and to remove any concrete that might otherwise remain and set during the periods between pourings. Platform hoists, instead of buckets, are sometimes used in connection with concrete towers. In such a case the concrete is discharged from the mixer into wheelbarrows which are run on to the hoists and raised to the level at which the work is being done. All the MIXING AND POURING CONCRETE 139 Fig. 85. Wear Goggles when Cutting Concrete. (See also Fig. 86,) precautions mentioned above, in connection with hoist- ing apparatus and wheelbarrows, should be faithfully observed. In addition, chocks or stops should be provided on the platforms of the hoists to insure proper placing of the wheelbarrows and prevent the handles from projecting beyond the edges of the platforms and 140 THE TRAVELERS INSURANCE COMPANY J-f'-K^i^^^M^i I'u;. 86. r.ocGLES Broken by a Flying Chip of Concrete. (Si^e also Fig. 8.S,) fouling the sides of the towers. A definite system of signals should also be arranged, so that the engineer will not start the hoists while the barrows are being put on or taken off. No one should be permitted to ride on these hoists. (See also paragraph 30.) 62. Miscellaneous. The disposal of discarded MIXING AND POURING CONCRETE 141 forms used for concrete work is an important safety problem. The boards of which the forms are composed contain man^^ projecting nails, and when the forms are removed after the concrete has set, these boards are often left lying about near the work. The projecting nails then become a serious hazard. Sometimes the boards are collected and heaped up in a disorderly pile, but the danger is only partially eliminated when this is done. On a large job it might not be considered feas- ible to remove or bend over the nails, but it is usually practicable to remove the boards to a safe distance and to pile them up in an orderly manner with the nails projecting downwardly, — and this should ahva^^s be done. (See also paragraph 64.) Furthermore, a good deal of the lumber that is used is undressed, and con- siderable of it also becomes broken, when stripping the forms, so as to have jagged ends and edges. The work- men engaged in handling this material should therefore wear serviceable gloves to protect their hands against splinters and slivers, as well as against projecting nails. Considerable chipping of concrete is necessary under certain conditions. This work may be done with an air hammer or with an ordinary hammer and a cold- chisel. In either case the workmen should wear suit- able goggles to protect their eyes against flying chips of concrete. Hand tools should also be dressed whenever they become "mushroomed" from prolonged use, be- cause otherwise burrs of metal are likely to break off from them and endanger the eyes. (See also paragraph 65.) X. GENERAL PRECAUTIONS. 63. Covering Floors. All openings in the floors should be either planked over, or substantially guarded with fences or with rails and toe-boards; and the unauthorized removal of planks that have been laid down to cover up openings should be absolutely pre- vented. It is of course necessary at times for sub- contractors' gangs to remove temporary flooring and Fir,. 87. Protective Plank Flooring in a Ventilating Shaft. (Note tliii- niaU^ri;Ll tliLit has fallen frum above and been caught by the covering.) GENERAL PRECAUTIONS 143 Fig. A Dangerous Floor-opening. (If a man coming through the doorway should heedlessly turn at once to his riglit, he would probably step into the opening and fall IS feet to the basement floor. Guard-rails should always be installed about such openings, at the earliest practicable moment.) 144 THE TRAVELERS INSURANCE COMPANY guard-rails, but they should be required to replace every such safeguard as soon as the exigencies of the work will permit. Unfortunately, the workmen on construction jobs usually have but little regard for this precaution, and they often remove protective planks and put them to other uses, as soon as the safety-inspectors go to another floor. They do this, not maliciously, but merely because they do not under- stand the paramount importance of keeping the open- ings co\-ered over. It is essential not only to cover up large openings in this way, but also to fill in small apertures about i'^^^- -^ -mji^ Fig. 89. An AccmENx-souRCE that is Frequently Ovek- LOOKED. (The opcnint; iinrk-r tlip enrl of tlic; runway slionld be boarded up, to prevent oljjects from passing through it and falling to tlie floors below.) GENERAL PRECAUTIOx\S 145 Fig. 90. An Unguarded Elevator Shaftway. (A workman fell into the shaftway at this point, and was killed.) columns, and all other similar places. Fragments of bricks, small pieces of board, tools, and other objects frequently fall through such openings and strike the men below. For this reason, also, the planks used for temporary flooring must be laid closely together, so that no small objects can fall between them. (See also paragraph 51.) In construction work the floor arches should be laid as soon as possible after the steelwork has been set, and should be kept within two floors of the der- ricks, whenever feasible. If it is not practicable to do this, the second floor below the erecting floor should be entirely planked over. One sj'stem that 146 THE TRAVELERS INSURANCE COMPANY has been tried with marked success consists in com- pletely planking over the erecting floor and the second floor under it, and shifting the lower of these two floors to the top every time the derricks are raised, so that it becomes, in its turn, the erecting floor. By this means all the men on the lower levels are protected, at all times, by at least one complete floor of planking, regardless of the operations that may be going on upon the erecting floor. It might be thought that the procedure here suggested would be a source of con- siderable expense, but experience shows that such is I-'iG. 91. Approved Guard-rah.s for Permanent Elevator Shaftways and Other Similar Openings. (In the centc-r of the picture there is also a guard for the protection of signal cords. In tliis connection, iiowever, note tlie remarks tinder I-^ig. 23, page 44.) GENERAL PRECAUTIONS 147 not the case. It saves a great deal of time for the steel contractor's men, by giving them a good flooring upon which to work at their bolting and riveting oper- ations while the next tier of beams is being placed; and the gain that is effected in this way should more than ofTset the cost of providing and handling the extra lumber. It is particularly important that the floors on which the derricks stand should always be planked over solidly, because men are traveling about upon these floors constantly, and tools and materials are specially likely to be dropped upon the other workmen below. In planking a floor, no matter for how short a time, special care should be taken to see that none of the planks are placed so that they can be tipped by step- ping upon their ends. Planks so set are often called "traps," and they have brought death or serious in- jury to many persons. (See also paragraph 51.) 64. The Nail Hazard. It is often extremely difficult to impress upon the men the importance of guarding against injuries from projecting nails; and yet it is probable that in building construction more accidents result from this particular hazard than from (7=^ Usual Method. (Dangerous.) Correct Method. (Safe.) Figs. 92 and 93. Hammering Down a Projecting Nail. 148 THE TRAVELERS INSURANCE COMPANY any other single cause. It is true that most of the injuries caused by nails are of minor importance, yet quite a sensible proportion of them result seriousl>', and the loss of a hand or a foot, from infection received in this way, is by no means uncommon. An injury from a nail should receive immediate medical treatment, because septic material is likely to be carried into the wound by the nail. Nails covered with dirt or rust are specially dangerous in this respect, but clean nails may also give rise to serious trouble by introducing septic matter from the skin or clothing of the injured man. When a nail-wound is properly treat- ed it will usually heal in a short time, but if it is neglected, blood poisoning or lockjaw may follow. Fig. 94. The Nail Hazard in Construction Work. GENERAL PRECAUTIONS 149 All projecting nails in boards, planks, and timbers should be carefully removed, hammered in, or bent over in a safe way; and if time will not permit of doing this immediately, the material should be temporarily stowed in piles with the points of the nails projecting downward, and attention should be given to the nails at the earliest practicable moment. Scaffold materials, concrete forms that have been removed (see also paragraph 62), and boards that have been used for protecting the corners of building stones are often thrown down carelessly, and these usually have numer- ous nails projecting from them that should be with- drawn or made safe. 65. Hand Tools. It is extremely important to keep all hand tools in the best possible condition. Edged tools should be kept sharp, and hammers, sledges, cold-chisels, drift-pins, drills, and other similar tools should be dressed frequently, to remove burrs that might otherwise fly off when the tools are struck, and cause injuries. Axes, picks, hoes, sledges, and other such imple- ments should be immediately repaired or discarded if their handles become split or broken. Provide pro- tective handles for cold-chisels and drills, to avoid injury in case the strikers miss the heads of the tools when cutting or chipping stone, concrete, or metal. Tools should not be left lying about on scaffolds or stepladders, nor on beams, nor in elevated places of any kind from which they might fall and cause injuries. Men working in gangs should be careful to keep a suitable distance apart, to avoid striking one another with their tools and implements. 150 THE TRAVELERS INSURANCE COMPANY Fig. 95. A Bar-guard on a Material Hoist. (Some meuns for holding \vlic'elbarr(jws in position is essential on all material hoists, to pre- vent Lircideiits like that shown in Fig. 96. Blocks or chocks for holding the le!;s of the bar- rows should be suljstituled for the bar-guard, whenever both sides of the hoist are used for entrance and exit.) GENERAL PRECAUTIONS 151 Fig. 96. Bar-guards Prevent Accidents of this Kind. (See also Fig. 95.) 152 THE TRAVELERS INSURANCE COMPANY When a number of tools or other small objects are to be hoisted to the working level they should not be lifted by the use of slings or ropes alone, but should be placed in suitable boxes, barrels, or buckets, in such a way that they cannot fall out. Mortar hods and brick hods should be kept in good condition, and any that are defective should be repaired or discarded. Brick hods should be loaded with care, and every precaution taken to prevent any of the bricks from falling out when the helpers are going up ladders, or passing along scaffolds or runways. 66. Wheelbarrows. See that all wheelbarrows are maintained in good condition. If the workmen have to push them through narrow doorways or passageways, protective handles should be provided, to guard the workmen's hands against being crushed or bruised. In placing a barrow on a material hoist, always make sure that no part of it projects beyond the edge of the hoist. When wheelbarrows are transported on hoists, the floors of the hoists should be provided with blocks to receive their legs, as noted in paragraph 61, page 139; and care should be taken to see that the legs of the barrows are in proper position with respect to the blocks, before the hoists are moved. Do not allow the men to leave wheelbarrows so that their handles project out into passageways. Many seri- ous accidents have been caused by persons colliding with these handles, in unexpected places. When barrows are empty, the men sometimes tip them to a nearly vertical position, and run with them. This practice is dangerous, especially when going down inclined runways, because the men are likely to stumble and be injured. (See also paragraph 59.) GENERAL PRECAUTIONS 153 67. Explosives. Explosives are frequently used in preparing foundations for buildings. It is also necessary, at times, to do more or less blasting in con- nection with demolition operations, although this should be avoided as far as possible. When explosives of any kind are used they should be put in charge of some one person who is known to be experienced and thoroughly trustworthy, and who should be held responsible for the exercise of all possible precautions in connection with the storage and use of them. A cool, dry place, protected from fire and lightning, is essential for the storage of explosives. If a consider- able quantity is kept on hand a special storage maga- zine should be provided, but it is unlikely that the amount ordinarily required for building operations will necessitate a special storage place of this kind. Never use steel or iron tools for opening boxes of dynamite. If the covers of the boxes are nailed on, use a hard-wood wedge and a wooden mallet, or a copper chisel. If the covers are secured with screws, use a screw-driver only for opening the boxes. Only as many cartridges as are needed for immediate use should be removed from the box, and the cartridges should be carried to the work in a dry box or bucket. Let somebody else carry the tamping stick, fuse (if fuse is used), and detonators — especially the detonators. The shot holes should be made ready before the dynamite is brought to the work, and the operations of priming, charging, tamping, and firing should be carried on as rapidly as is consistent with careful work. Dynamite should never be used while frozen or partly-frozen, and sticks of it should never be slit, bent, kneaded, or otherwise manipulated while in this 154 THE TRAVELERS INSURANCE COMPANY condition. Frozen dynamite should be carefully thaw- ed in special thawing kettles heated by warm water, or in some other safe and approved way. It is highly dangerous to thaw dynamite by warming it in front of a fire, or by placing it in ovens, or on shelves over stoves or steam radiators. Electrical shot-firing is to be preferred, because the charge can then be set off at any distance desired, the firing instant can be exactly determined, and accidents due to retarded and premature firing are largely eliminat- ed. If fuse is used, it should be in first-class condition, and should not be brittle nor defective in any way what- soever. Damaged or inferior fuse often causes blasts to be premature, or to be delayed. Blasting caps should always be fastened to fuse by a crimping tool, specially made for the purpose. It is highly dangerous to use the teeth for this purpose, or to employ any other make- shift method. The caps should not be attached to the fuse in or near the storage house, and they should not be inserted in the cartridges until just before these are placed in the holes, ready for tamping. The stemming (or tamping) should consist of clay or of loosely-shaken dry sand, so that no sparks may be produced. The tamping rods should be made wholly of wood. Steel or iron rods should never be employed, under any circumstances; and the wooden rods should never have iron ferrules, nor contain tacks or nails, nor have any other metal parts whatsoever. When a shot is about to be fired, all persons who are near the place should receive ample warning, and the fuse should not be lighted until it is absolutely certain that every one has been warned, and that no one is in a dangerous position. GENERAL PRECAUTIONS 155 A charge that has misfired should not be approached for at least two hours, and it is safer to leave it for an entire day, before making an examination. No at- tempt should be made to fire a charge that has failed to explode the first time, nor to tamper with it in any way. A new hole should be drilled about two feet from the first one, and a fresh charge inserted in it and fired. It is impossible, in the space here available, to describe all of the dangers that are associated with the use of explosives. Additional information concerning special points in connection with explosives will be furnished by the Engineering and Inspection Division of The Travelers Insltrance Company, upon request. 68. Life Lines and Safety Belts. Many serious accidents might be averted if the men were required to wear safety belts secured to stout life lines whenever it is practicable to do so. Under certain conditions, for example during the early stages of construction, the steelworkers can seldom use these safeguards with advantage, because they have to move about freely and almost continuously. There are times, in fact, when life lines might be distinctly dangerous to the men, by impeding their movements in critical situations; but there are other times, beyond all question, when the safety of the steelworkers would be materially increased by the use of life lines. Life lines and safety belts should be used by men working on steeply-pitched roofs, and by those who are installing, adjusting, and inspecting the machines and other parts of suspended scaffolds. (See also page 99.) Painters should also be provided with these safeguards while at work on the steel columns and other structural members that have been erected, and should 156 THE TRAVELERS INSURANCE COMPANY Fig. 97. Working Under Dangerous Conditions. (Stc-cKvorkcrs are necessarily exposed to many grave risks, and it often happens that they mii^t rely, for safety, mainly or wholly upon their own coolness and judgment. The man here shown should wear a safety belt.) be required to use them faithfully. There are numerous other operations, also, which would be made less hazardous by requiring the men to use these safety devices. The safety belt is used quite generally in other countries, and there is no good and sufficient reason why we should not adopt it far more generally in the United States. Great care should always be taken to see that the life lines are safely secured to strong, firm supports, and they should be no longer than is necessary in order to permit the work to be done without inconvenience. Otherwise, if a man should fall, the rope would be sub- jected to a snapping stress of unnecessary severity, and GENERAL PRECAUTIONS 157 a- 1 Fig. 98. Painting the Steelwork of a "Skyscraper." (The workman should have worn a safety belt and life line.) it would be more likely to break than if it were shorter. Inspect and thoroughly test all life lines and safety belts at frequent intervals, and see that they are in first-class condition in all respects. 69. Storing and Piling Materials in Buildings under Construction. In congested districts all material should be stored in the building as soon as the building operations will permit. Crushed stone, gravel, sand, bricks, and cement should preferably be stored below the level of the street floor. They may be delivered to the storage place through chutes which may be locat- ed at the first or street floor level inside of the building or near the street curb outside of the building. When chutes are employed they should be provided with 158 THE TRAVELERS INSURANCE COMPANY substantial covers, which should be kept in place when the chutes are not in use, or with guard-rails and toe- boards. Terra cotta or tile partition and floor blocks must be handled with considerable care, to prevent excessive breakage, and therefore should not be thrown down from an elevation or be delivered through chutes. It is customary to bring these blocks into the building under construction on trucks or wagons, and to pile them on the street floor. They should be carefully piled, to a height not exceeding 6 feet, and the piles should be braced or propped, if necessary, to prevent them from toppling over. Equal care should be exercised in Fig. 99. Poorly-ph.kd Floor Tiles. (These sliould be stnwerl mucli mon' carefully, in orderly and regular piles not more than six blocks in height.) GEXERAL PRECAUTIOXS 159 piling bricks, lumber, structural steel, and other material, both inside the building and in the street or elsewhere. Bags of cement should not be piled more than 10 bags high, and unless each end of the pile rests against a wall or other substantial support, the end bags should be cross-piled, for greater security. The bags in the outer tiers should be placed with their mouths toward the center of the pile. When removing bags do not take them all from one part of the pile, but keep the top of the pile as nearly level as possible. Crushed stone, sand, and gravel exert considerable side pressure when stored in quantity, and care must therefore be taken to see that walls or partitions against which they may be piled are amply strong to sustain the load. 70. First-aid and Hospitals. Provide the neces- sary equipment (including stretchers) for giving first- aid treatment in case of accident. On every construc- tion job a first-aid cabinet should be kept in some convenient and accessible location. It should contain all of the supplies needed for use in first-aid work, and it should be placed in charge of some person who is known to be competent to render first-aid treatment properly and effectively, and whose services are immediately available at all times. The instruments and supplies us- ually recommended for a first-aid cabinet are as follows: Instruments: 1 pair scissors. Thumb forceps. Tourniquet. Graduated medicine glass. 160 THE TRAVELERS INSURANCE COMPANY Drugs: 2 ounces of aromatic spirits of ammonia. 2 ounces of 4 per cent, boric acid solution. 2 ounces of alcoholic iodine solution, half strength (for external use). 2 collapsible 3-ounce tubes of vaseline, containing 3 per cent., by weight, of bicarbonate of soda (for burns). 2 ounces of castor oil for eye injuries. Dressinc;s: 1 dozen sterile gauze bandages, in assorted sizes. 1 spool of adhesive plaster, 1 inch by 5 yards. 3 packages, yi oz. each, of absorbent cotton. 3 packages, 1 yard each, of sterile gauze. Splints of assorted sizes (for fractures). Wooden applicators wound with cotton. Wooden tongue-depressors. All bottles or other containers for drugs or other substances should be plainly labeled, and the specific purpose for which the contents are to be used should be printed on the labels. On many large construction jobs hospital rooms are provided, having facilities for more extensive treatment, and with trained nurses in constant attend- ance. These are recommended wherever it is prac- ticable to provide them. In all cases, arrangements should be made so that a competent physician may be procured with the least possible delay. The addresses and telephone numbers of several who are near by should be posted in a conspicuous place. 71. Sanitation. The toilet facilities furnished on GENERAL PRECAUTIONS 161 building-construction jobs are often inadequate, al- though they are highly important. Temporary accom- modations should be provided, and should be main- tained until the permanent equipment has been put in place and is in operation. A sufficient number of closets should be provided and they should be conven- iently and accessibly located. On high buildings they should be installed as the construction work progresses so that at no time will the workmen be obliged to travel more than four stories to reach them. If the building is four stories or less in height, closets may be provided outside the building, but they should not be more than 100 feet distant. The closets should be kept in good, sanitary condition, and suitable disinfectants or deo- dorizers should be supplied for them and used frequent- ly. The installations and the disposal of all wastes should conform with the regulations of the health offi- cials having jurisdiction in the locality where the build- ing is being erected. Drinking water should be supplied to the workmen, and it should be obtained from a source that is known to be free from contamination. So far as possible the common drinking cup or tin dipper should be dispensed with and drinking fountains substituted. 72. Miscellaneous. Provide adequate artificial light wherever necessary, throughout the building, and especially in passageways and on stairways. Incan- descent electric lamps that burn continuously through- out the working period should be inspected twice a day, and all broken or burned-out lamps should be immediately replaced by new ones. It is specially important to keep all stairways, passageways, and gangways free from obstructions 162 THE TRAVELERS INSURANCE COMPANY of every kind, and the men should not be allowed to store materials or supplies in these places. Keep all materials and supplies well away from the edges of hoist shaftways, stair wells, and other similar openings, and also from the outside walls of the building. Loose, light material should not be left lying about on roofs, nor on upper floors that are not closed in, especially when high winds are prevailing, because it is likely to be blown off into the street and cause injuries. Bolts, nuts, and rivets should not be left lying about, but should be collected daily and placed in kegs or other suitable receptacles. Caution the men with regard to handling bags Fig. 100. Keep all Material Well Back from the Edges OF Open Floors. GENERAL PRECAUTIONS 163 Fig. 101. Using a Cloth Screen to Prevent Chips of Stone FROM Flying into the Street. (The workman was less mindful of his own safety, however, as he was not wearing e:.'e protectors.) containing lime, because these bags sometimes burst and the lime gets into the e^'es of the workmen, causing serious and painful injuries. Men engaged in cutting or chipping concrete, stone, or metal, should wear suitable goggles or eye- protectors to prevent injuries to the eyes from flying chips. Similar eye-protectors should be worn by the men when doing any other work that is likely to cause injury to the eyes. (See also paragraph 62.) When chipping is being done in exposed places the public should be protected against flying pieces of stone or metal by stout screens placed in positions where they will intercept the chips. When a number of men are working in a group upon cutting or trim- 164 THE TRAVELERS INSURANCE COMPANY ming operations of this nature, tliey should also be pro- tected /ro;;? one another by means of similar screens. 73. Inspections. No one thing is more essential to safety in building operations than intelligent and thorough inspections; and the service should be fre- quent, because the conditions that prevail in such work change quite rapidly. If the operation is a large one, it is often advisable to have at least one inspector on the premises constantly, while the work is progressing most actively; and on the very largest jobs it may at times be wise to have two or even more men thus engaged. On a small job it is not feasible to maintain a man continuously for inspection work only, but in a case of this kind it is easy for the foreman to have personal knowledge of every important condition, and with the assistance of a professional inspector at reasonable intervals he should be able to conduct the operation in a safe way. A plan that has been found to work well in opera- tions of average size consists in making a preliminary inspection as soon as the work is started, and submit- ting recommendations for the improvement of condi- tions and the installation of suitable safeguards. On his next visit the inspector sees that the recommenda- tions have been carried out, or are in process of ful- filment, and submits new recommendations to cover new conditions that have arisen on account of the progress of the work. This routine is followed at each inspection visit, to insure safety at all times. It is reasonable to suppose that the best inspec- tion service will be rendered by a corporation that has a large money-interest staked upon the safety of the men, because a corporation of this kind has a definite GENERAL PRECAUTIONS 165 and positive material incentive to thoroughness and efficiency. The contractor also has an interest in the matter, financial as well as humane; but he has many other things to think of at the same time, and he can hardly give the safety problem the minute attention that it must receive, if accidents are to be prevented or efTectually reduced. The compensation and liability insurance company is the most logical source from which efficient inspections may be expected, and if it is alive to its possibilities and responsibilities it will maintain an inspection force that is competent to deal with the accident problem in an intelligent and effective manner. INDEX. Accidents, fatal, caused by concrete mixers, 130, 132. Acet3'lene gas is injurious to health, 14. tanks, safe handling of, 15. — See also Oxy-acetyloie. Air, compressed, and practical jokes, 128. hose, care of, 128. Arches. — See Floor arches. Beams to be secured before being cut, 13. Belts, safety, 99, 155. Bents, supporting, to be placed under derrick, 82. Blasting, misfires in, precautions concerning, 155. — See also Explosives; Shot-firing. logs. — See Logs, blasting. Blocks for nianila ropes and wire cables should not be used interchangeably, 47. lead, guards for, 47. Blood poisoning from nail wounds, 148. Blowpipe. — See Welding eguipment. Boilers for hoisting engines, precautions in the use of, 36. Brakes for hoisting engines, 36. solenoid, for electric motors, 39. Breast derricks. — See Derricks, breast. Bricklayers' pole scaffold. — See Scaffolds. Bricks should not be piled directly upon the ground, 12. Bridges. — See Sidewalk sheds and bridges. Bridle slings. — See Slings. Bucket, concrete, danger of riding in, 137. Buildings under construction, e.xcluding persons from, ii. Bull-tail, description of, 86. Cabinets, first-aid, contents of, 159. Cables passing through floors to be guarded, 45. and sheaves, relative sizes of, 46. for supporting suspended scatfolds, material for, 98. Carbon monoxide, 14. Cement, bags of, safe piling of, 159. Chain slings, — See Slings. 168 Index Chimneys should not be pulled down bodily, 8. Chutes, material, used in demolition work, 7. distributing, for concrete, 135. concrete-distributing, stoppages in, and methods of cleaning, 138. for delivering materials to storage places, 157. Columns, climbing up and sliding down on, 12-1. Compressed air — See Air. Concrete, chipping, eye hazard in, 141. forms, disposal of discarded, 141. mixing and pouring, 129. mixers, mechanical, and their hazards, 129. towers. — See Guys; Towers. Contractor's ofiice, location of, 26. Cords. — See Signal cords. Coverings, street, 30. Crank shafts of steam shovels to be guarded, 24. Cutting equipment, oxy-acetylene, safe handling of, 14. Cylinders, compressed-gas. — See Tanks. "Dead-logs," 79. "Dead-men", 79, SO. Demolition work, general counsel concerning, 1. should proceed systematically, 4. Derrick bay should be fully ri\'eted or bolted, 82. booms, "topi)ing up", 89. foot-blocks, method of securing, 85. number of guys for, 81, 135. sheaves, size and arrangement of, 76. Derricks, general types of, 75. general precautions in the use of, 89. inspection of, 89. lubrication of, 89. mechanical brakes for, 86, 89, 135. supporting bents for, 82. breast or house, handles to be secured in place, 86. to be guyed from front and back, 88. setting and securing bases of, 89. guy, general description of, 79. method of attaching guys to, 79. methods of anchoring, 79. stiff-leg, material and construction of, 75. effect of improperly-fitted goose-necks for, 76. importance of weighting properly, 79. Detonators. — See Explosives. Doctors, 160. Doorways beneath scaffolds should be guarded, 111. Index 169 Dressings for first-aid, 160. Drugs for first-aid, 160. Dust, wet floors to keep down, 18. Dynamite, safe method for opening boxes of, 153. frozen, dangers of, 153. Electric wires, danger from, when demolishing buildings, 3. Engines. — See Hoisting engines. Excavation work, general suggestions for, 19. Excavations to be guarded on all sides, 19. material to be kept away from edges of, 19. should be kept free from building materials, 23. Explosives used in excavating work, 23. storage magazine for, 153. precautions in the use of, 153. — See also Blasting; Dyyiamite. Eye-protectors. — See Goggles. Eyes, acetylene flame injurious to, 14. Falling objects, protection against, 4, 17. Fence guards used in demolition work, 4. Fire hazard when using acetylene torches, 14. First-aid equipment, 159. cabinets. — See Cabinets. Flashboards for wagons and motor-trucks, 8. Floor arches to be laid as soon as possible, 145. beams used for propping walls, 3. on which derrick stands to be planked over solidly, 147. blocks. — See Terra cotta; Tile. Flooring, temporary, to be placed below erecting floor, 145. Floors, use care to avoid overloading, 13. openings in, to be covered over, 17. erecting, to be covered over tightly, 126. Foot-blocks for guy derricks, method of securing, 85. Forms, discarded concrete, disposal of, 141. Foundations, removing, in short sections, 19. undermining, 19. Fuse. — See Explosives. Gangs, erecting, 124. Gangways to be kept free from obstructions, 161. Gas, acetylene, is injurious to health, 14. illuminating, danger from, when demolishing buildings, 3. compressed. — See Acetylene; Oxygen; Tanks. Gates for material chutes, 7. for material-hoist shaftways, 47. k;. 170 Index Glass, broken, should be removed from buildings, 17. Gloves, for operators of acetylene torches, 14. for steehvorkers, 124. Goggles for operators of acetylene torches, 14. for men engaged in cutting and chipping, 163. Goose-necks. — See Derricks, stiff-leg. Guard-bars for material-hoist shaftways, 48. Guards for cables, blocks, and sheaves, 44. for hoisting engines, 36. for steam shovels, 23. — See also Fence guards. Guys for concrete towers, 137. — See also Derricks, guy. Hammers, pneumatic, securing snaps and plungers of, 128. Hoisting heavy objects, special precautions for, 35, 57. towers. — See Towers. engines, location and protection of, 34. types of, 36. guards, for, 36. Hoists, material, protection for, 47. covering for overhead work of, 51. prohibit riding on, 57. passenger, to be installed as early as possible, 61. safety devices for, 62. protection for, 62. should not be overloaded, 62. regular operators to be provided for, 62. platform, in connection with concrete towers, 138. Hoppers of concrete mixers, hazards of, 131. Horse scaffolds. — See Scaffolds. Hose, air, care of, 128. for welding equipment, care of, 16. Hospital rooms on construction jobs, 160. House derricks. — See Derricks, breast. House- wrecking. — See Demolition. Illumination. — See Light. Independent pole scaffold. — See Scaffolds. Inspections, methods of making, and value of, 164. Instruments for first-aid, 159. Ladders on steam shovels, 23, 24. materials for, 113. builders' portable cleat, 114. of double width, 115. Index 171 Ladders to extend above landings, 115. securing and bracing, 115. safety shoes and spurs for, 117. safe length of, 117. sheathing underneath, 117. joining, 118. on concrete towers, 137. Ladderways, separate, for ascending and descending, 117. Lamps, electric, used for signaling, 42. incandescent electric, inspection of, 161. Life lines for men who adjust suspended scaffolds, 99. the importance of using, 155. Light, artificial, to be provided where necessary, 161. Lime, care in handling bags of, 162. Lockjaw caused by nails, 148. Logs, blasting, used for anchoring derricks, 80. Lubrication of derricks, 89. Magazine. — See Explosives. Magnets should not be used for hoisting compressed-gas tanks, IS. Manila-rope slings. — See Slings. Material, long, precautions in hoisting, 55. not to be hoisted through stairway openings, 57. light, should not be left on roofs, 162. hoists. — See Hoists, material; Towers, hoisting. Materials, removing, from upper floors, 6. heavy, to be hoisted outside of building, 35, 57. to be kept back from edges of openings, 162. storage of, 11, 32, 111, 157. Men, selecting, with reference to their capabilities, 2. Mercury-filled U-tube indicates tipping of steam shovel, 25. Metal cut by oxy-acetylene flame, 13. Misfires. — See Blasting. Mortar beds under scaffolds to be roofed over. 111. Motors, electric, for hoisting, 38. solenoid brakes for, 39. Motor-trucks, flashboards for, 8. used in excavation work, 22. loading, by means of steam shovels, 24. Nail hazard, the, 147. Nails, removal of, in demolition work, 13, 18. in discarded concrete forms, danger from, 141. serious nature of injuries caused by, 148. Needle-beams for riveters' scaffolds, 106. Nurses on con.struction jobs, 160. 172 Index Office, contractor's, location of, 26. Openings for hoisting, protection for, 17. in floors to be guarded, 142. small, to be covered over, 144. — See also Floors. Outrigger scaffolds. — See Scaffolds. 0\erhead-type suspended scaffold, description of, 97. Oxy-acetylene cutting-flame used in demolition work, 13. — See also Cutting; Welding. Oxygen tanks, keep oil and grease away from, 15. Passageways beneath scaffolds should be guarded. 111. to be kept free from obstructions, 161. Passenger hoists. — See Hoists, passenger. Pavements, protection for, 31. Physicians, 160. Piling of materials. — See Storage. sheet, necessary when demolishing buildings, 19. Platforms, protective, on buildings, 30. on hoisting towers, 61. rivet-heaters', 126. over concrete mi.xers should be guarded, 134. Platform-type suspended scaffold, description of, 95. Pole scaffolds. — See Scaffolds. Riding on material hoists prohibited, 57. on loads prohibited, 124. Rivets, bolts, and nuts to be collected daily, 162. passing, through pipes, 127. throwing, safe methods of, 126. Rope. — See Signal cords. Runways, to be effectively braced, 120. to have hand-rails and foot-boards, 121. number of planks in, 120. arrangement of ends of planks on, 122. to be strong and well-constructed, 133. Safety belts. — See Belts, safety. Sand, storing and handling, methods and equipment for, 133. Sanitation important on construction jobs, 160. Scaffolds to be used when removing thin or weak walls, 10. overhead protection for, 109. in ventilatmg and elevator shafts. 111. protection for men working under, 111. should be removed as soon as possible, 112. types of, chiefiy used by bricklayers and masons, 91. Index 173 Scaffolds, bricklayers' pole, description of, 91. independent pole, description of, 9-t. horse, their construction and use, 102. supporting and bracing, 103. for exterior work, 104. outrigger, description of, 101. riveters', their construction and use, 106. painters', guard-rails for, 107. to be tested, 107. precautions in the use of, 107. suspended, the two principal types of, 95. precautions in connection with, 98. cables for supporting, 98. shifting the cables of, 99. Screen to intercept flying chips of stone, 163. Set-screw causes fatal accident, 130. Shaftways of material hoists, protection for, 47. Sheaves, for hoisting, 46. self-lubricating, cast-steel, 47. and cables, relative sizes of, 46. — See also Derrick sheaves. Sheds. — See Sidewalk sheds. Shoes for steel workers, 124. Shoring buildings that are to be demolished, 3. adjoining buildings in demolition work, 2, 19. Shot-firing, electrical, preferred for blasting, 154. Shovels, electrically operated, 25. steam. — See Steam shovels. Sidewalk sheds, description of, 4. storage of material on, 13. and bridges, 26. Signal cords, joining the ends of, 42. protection for, 42. run through pipes, 42. Signaling systems for hoisting, 40, 140. Signals, manual, for hoisting, 40. Signs, danger, at discharge end of material chutes, 8. "Skip," 131, 133. Slings, precautions in the use of, 65. adjusting about loads, 66. preservati\'e treatment of, 67. effect of inclination of, 68. to be protected when loads have sharp corners, 72. bridle, 73. toggle, 73. toggle column, 73. 174 Index Slings to be locked up when not in use, 74. two complete sets advisable, 74. should ha\'e identification tags, 74. wire-cable, preferable to chains or fiber ropes, 66. sharp bends to be avoided, 66. proper method of inspecting, 66. Soapsuds for locating leaks in welding equipment, 16. Solenoid brakes. — See Brakes. Stagings. — See Scaffolds. Stairs and stair railings to be left in place as long as possible, 18. Stairways to be installed as rapidly as possible, 118. storing material on, 118. to be kept free from obstructions, 161. Steamboat ratchets for tightening derrick guys, 85. Steam shovels, in general, 23. persons not to be allowed on, 24. device to indicate tipping of, 25. precautions to prevent upsetting, 25. Steel, structural, guiding loads of, when hoisting, 1 28. Steelworkers, precautions to be observed by, 124. Stone, storing and handling, methods and equipment for, 133. Storage of materials, 11, 32, 111, 157. Storms, work to be discontinued during, 124. Street coverings, openings in, to be guarded, 30. — See also Pavements. Switchboards and switches, 39. Suspended scafToIds. — See Scaffolds. Table showing stress changes in slings for various inclinations, 71. Tanks, compressed-gas, care of, 14. to be lashed in place, 15. safe storage of, 15. connections for, 16. Terra cotta blocks, handling and piling, 158. Tile floor-blocks, handling and piling, 158. Tiles. — See Floor tiles. Toggle slings. — See Slings. Toilet facilities on construction jobs, 160. Tools, care in hoisting, 152. hand, to be kept in good condition, 141, 149. Torch. — See Welding equipment. Towers, concrete, safety in connection with, 135. hoisting, safe construction of, 57. should not be extended to ultimate height, at first, 58. method of sheathing, 58. "Traps" in temporary floors to be avoided, 147. Index 175 Turn-buckles, steamboat ratchets to be useci in place of, 85. Vehicles. — See Motor-trucks; Wagons. Wagons, tlashboards for, 8. used in excavation work, 22. loading, by means of steam sho\els, 24. Walls, building, removing in sections, 8, 10. shoring, 19. of excavations to be braced, 19. to be inspected frequently, 22. Water, drinking, 161. Welding equipment, safe handling of, 14. Wetting-down floors to prevent dust, 18. Wheelbarrows, guides for, on material hoists, 57, 139, 152. care of, 132. storing, 152. protective handles for, 152. Winds, high, work to be discontinued during, 124. Woolworth Building, 30. Wrecking. — See Demolition work. Cornell University Library TH 443.T75 1921 Safety in building construction 3 1924 002 408 759 Group Insurance LIFE • ACCIDENT • SICKNESS Being Rapidly Adopted by Great Concerns throughout the U. S. A. XTEWER than Compensation, -^ ^ and just as much a business essential. It is being widely adopted because it fills a serious need for a better expression of friendly interest on the part of employers towards their employ- ees. It also obtains for the employer the friendship and in- fluence of the home. Great names taken at random from the long list of famous concerns carrying Group insurance in The Travelers THE AMERICAN WOOLEN COMPANY NATIONAL LAMP WORKS, AND THE VICTOR TALKING MACHINE COMPANY EDISON LAMP WORKS OF THE THE WASHBURN-CROSBY COMPANY GENERAL ELECTRIC COMPANY THE WESTINGHOUSE ELECTRIC & MFG. CO. JOHN WANAMAKER, PHILADELPHIA THE BURROUGHS ADDING MACHINE COMPANY CRANE COMPANY Write for further information GROUP DEPARTMENT THE TRAVELERS HARTFORD, CONNECTICUT STOPPING ACCIDENTS BY CONTRACT INSURANCE is a sub-contract — worthy of all care in the letting. The great men of the structural world to-day do not trust to their own lieutenants for the promotion of safety, nor to their own resources for the payment of claims. They choose the mo^ sub^antial and moS progressive casualty company they can find and enter into a contradt to place all these matters on the company's shoulders. CflHumanity suggests this course. Good business sense confirms ^the suggestion. You who built that skyscraper of gicEiniing marble: Are you able to think of it as a monument to your ability, or only as the headstone of the men who were killed in its construction? You who are putting up those great factory buildings: Do you want your profits to be drawn on for a quarter of a century or more to meet payments for compensation to fatherless families? WHEN TRAVELERS EXPERTS BEGIN. THE ACCIDENTS STOP J The first thing THE TRAVELERS docs is to prevent the accidents. To accomplish this it brings to bear the finest inspection service in the world, of engineers trained through long years in the detection of danger. They make the work FASTER, as well as safer. TRAVEiXRS Inspection economizes work-hours; for every contractor knows that a bad accident demoral- izes the entire force for hours afterward. A few hundred dollars in premiums saves hundreds of thousands In accidents. And. as the work achieves a record for safety, the premium charge grows smaller. f^The TRJiVELERS is the greatest casualty company in the ^ world because it has always been the leader in preventive and safety work. Its policies cover the contractor's responsibility for accidents, whether they happen to his employees or to the public. And TRAVELERS POLICIES COST NO MORE THAN OTHERS. Ask any agent about policy forms and about the books and booklets on safety. THE TRAVELERS INSURANCE COMPANY Hartford, Connecticut