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IC 
 
 8950 
 
 Bureau of Mines Information Circular/1983 
 
 Fresnel Lens Blind Area Viewers 
 for Improved Mine Equipment 
 Safety and Productivity 
 
 By Guy A. Johnson 
 
 UNITED STATES DEPARTMENT OF THE INTERIOR 
 
Information Circular 8950 
 
 tl 
 
 Fresnel Lens Blind Area Viewers 
 for Improved Mine Equipment 
 Safety and Productivity 
 
 By Guy A. Johnson 
 
 UNITED STATES DEPARTMENT OF THE INTERIOR 
 James G. Watt, Secretary 
 
 BUREAU OF MINES 
 Robert C. Horton, Director 
 
Library of Congress Cataloging in Publication Data: 
 
 
 \XA <f{ 
 
 <b° 
 
 yfSt 
 
 r 
 
 Johnson, Guy A 
 
 Frcsnc] lens blind area viewers for improved mine equipment safety 
 and productivity. 
 
 (Information circular ; 8950) 
 
 Includes bibliographical references. 
 
 Supt. of Docs, no.: I 28.27:8950. 
 
 1. Mining machinery — Blind-area viewers. 2. Kresnel lenses. 1. 
 Title. II. Series: Information circular (United States. Bureau of Mines) ; 
 8950. 
 
 -m2&57U4- [TN345] 622s [622'.8] 83-15013 
 
CONTENTS 
 
 Page 
 
 Abstract 1 
 
 Introduction 2 
 
 Design, development , and debugging of first-generation prototype 5 
 
 Second-generation, low-profile design 6 
 
 Related work on collision protection of mine equipment 11 
 
 Commercialization and cost-effectiveness analysis 13 
 
 Summary 15 
 
 ILLUSTRATIONS 
 
 1. A 220-ton-capacity truck undergoing maintenance in an Arizona copper mine. 3 
 
 2. Typical blind areas around a large haulage truck 3 
 
 3. Maintenance vehicle run over by a large haulage truck 4 
 
 4. Large front -end loader backing over a pickup truck 4 
 
 5. Typical "whip" used in surface mines to warn haulage truck drivers of the 
 
 presence of smaller vehicles 6 
 
 6. Components of the improved visibility system for large haulage vehicles... 6 
 
 7. Increased driver f ield-of-view with the improved system for large haulage 
 
 t rucks 7 
 
 8. Improved right-side visibility with the downward-looking blind area viewer 7 
 
 9. Components of the first-generation fresnel lens blind area viewer 8 
 
 10. In-mine, on-vehicle test of first-generation prototype hardware 8 
 
 11. Design of second-generation blind area viewer 10 
 
 12. Second-generation blind area viewer 10 
 
 13. Mockup testing of the second-generation blind area viewer 11 
 
 14. View through the second-generation blind area viewer during the mockup 
 
 testing 11 
 
 15. Initial in-mine testing of second-generation blind area viewers on a 170- 
 
 ton-capacity truck 12 
 
 16. On-truck. testing of three viewers 13 
 
 17. Testing the viewer on the back of a large front-end loader 14 
 
 18. View of a car through the blind area viewer on a large front-end loader... 14 
 
 19. Close-in collision warning device 15 
 
 20. Prototype CCTV rear-viewing system in an Arizona copper mine 15 
 
 TABLES 
 
 1. In-mine testing of the first-generation improved visibility system proto- 
 
 type hardware 5 
 
 2. In-mine testing of the second-generation, low-profile blind area viewers.. 9 
 
FRESNEL LENS BLIND AREA VIEWERS FOR IMPROVED MINE EQUIPMENT 
 SAFETY AND PRODUCTIVITY 
 
 By Guy A. Johnson 
 
 ABSTRACT 
 
 Combining contract and in-house research, the Bureau of Mines has de- 
 veloped and in-mine-tested a novel device to improve the f ield-of-view 
 of operators of off-highway mining equipment. This device utilizes a 
 downward-looking, flat fresnel lens. The lens, plus louvers to reduce 
 glare, is housed in a protective steel structure. The complete unit is 
 called a blind area viewer. The viewer, when mounted on the right- 
 front corner of the deck of most large haulage trucks, will increase a 
 driver's direct f ield-of-view from about 35 pet (of where he/she has to 
 drive) to about 80 pet. The improved visibility allows the driver to 
 see possible collision hazards and roadway obstacles better, thus im- 
 proving mine safety and increasing productivity. Economic analysis 
 shows that the blind area viewers, which are now commercially avail- 
 able, pay for themselves in about a month on a 170-ton-capacity truck. 
 The viewers are also applicable to other large mining equipment, such 
 as front-end loaders, draglines, and downhole drills, or any place 
 where seeing around a corner would be advantageous, such as along con- 
 veyor flights in processing plants during startups. 
 
 Supervisory mining engineer, Twin Cities Research Center, Bureau of Mines, Minne- 
 
 apolis, Minn. 
 
INTRODUCTION 
 
 As mine haulage equipment becomes 
 larger in order to increase productivity 
 and cut costs, the driver's f ield-of-view 
 becomes more restricted because the 
 truck's cab is pushed back under the pro- 
 tection of the truck box lip. Also, in 
 order to increase maintenance efficiency, 
 a great deal of ancillary equipment is 
 installed on the truck's radiator deck, 
 thereby further restricting the driver's 
 view and increasing the hazard of mine 
 vehicle collisions. Other problems, such 
 as excessive tire wear and slow vehicle 
 movement, can be related to the driver's 
 inability to see clearly the haulage road 
 and the loading and dumping areas. 
 
 To help solve this growing problem of 
 impaired visibility, the Bureau of Mines 
 worked with mining officials, heavy 
 equipment manufacturers , and personnel of 
 the Mine Safety and Health Administration 
 to develop and in-mine test reasonably 
 priced, rugged hardware for retrofit on 
 large haulage vehicles. One possible so- 
 lution was to use closed-circuit televi- 
 sion (CCTV) technology, but Bureau re- 
 search indicated that although CCTV may 
 help to reduce specific problems that oc- 
 cur during backing up at high dump points 
 (e.g., mountain tops), expensive mainte- 
 nance is required in order for the system 
 to be reliable in the harsh mining envi- 
 ronment. Another option was to improve 
 mirror technology. The use of larger 
 convex mirrors provided a simple and good 
 way to improve the rearview capability. 
 
 2 Bureau of Mines. Improved Visibility 
 Aids for Large Haulage Vehicles. Tech- 
 nol. Transfer film, 1980, 14 min. 
 
 Johnson, G. A. Improved Visibility 
 System for Large Haulage Trucks. Pres. 
 at 1980 Off-Highway Equipment Show, Mil- 
 waukee, Wis. SAE preprint 800934, 17 
 pp.; available from G. A. Johnson, Twin 
 Cities Research Center, BuMines, Minne- 
 apolis, Minn. 
 
 However, the major hazard area of a 
 vehicle — the right-front blind area — 
 still existed. This led to the develop- 
 ment of the fresnel lens blind area 
 viewer. 2 
 
 Although operators of today's huge 
 equipment need improved f ield-of-view, it 
 should be emphasized that smaller equip- 
 ment can also use relevant technology. 
 As an example, there is much congestion 
 in many sand and gravel and crushed stone 
 operations, especially those where the 
 public has access to the pit and plant. 
 A medium-sized front-end loader can eas- 
 ily back over a street vehicle parked in 
 its rear blind area. Installing fresnel 
 lens blind area viewers on the rear of 
 front-end loaders is proving very worth- 
 while in such situations. Also, because 
 there is much pedestrian traffic in ura- 
 nium pits (for example, geologists di- 
 recting the loaders to the highest grade 
 material) , viewers are needed by even the 
 small, 35-ton-capacity trucks. These 
 trucks have a bad right-front blind area, 
 and a driver, especially on a hard right 
 turn, can easily be on top of in-pit per- 
 sonnel before there is time to avoid 
 them. 
 
 Most of the references to mine equip- 
 ment in this report target the sort of 
 large haulage vehicles shown in figure 1, 
 but their extensive blind areas (fig. 2) 
 and resulting danger (as dramatized by 
 the crushed maintenance vehicle in figure 
 3) are typical of other large equipment 
 such as front-end loaders (fig. 4). 
 
 . Improved Visibility Systems. 
 
 Paper in Surface Mine Truck Safety. Pro- 
 ceedings: Bureau of Mines Technology 
 Transfer Seminars, Minneapolis, Minn. , 
 June 25, 1980, Birmingham, Ala., July 9, 
 1980, and Tuscon, Ariz., July 24, 1980. 
 BuMines IC 8828, 1980, pp. 22-39. 
 

 . d#*. 
 
 FIGURE 1, . A 220=ton-capacity truck undergoing maintenance in an Anzona copper mine, 
 
 150 ton 
 
 ©I 
 
 25ft; 
 
 60 ft 
 
 80 ft 
 
 M 
 
 Typical blind areas around a lege haulage truck 
 
Jt 
 
 FIGURE 3. - Maintenance vehicle run over by a large haulage truck. 
 
 FIGURE 4. - Large front=end loader backing over a pickup truck. 
 
DESIGN, DEVELOPMENT, AND DEBUGGING OF FIRST-GENERATION PROTOTYPE 
 
 In 1976, the Bureau contracted with the 
 Tracor MBA Corp. to study the visibility 
 problem and outline solutions. This work 
 was built on the successful development 
 and testing of automatic fire protection 
 systems for large haulage vehicles. It 
 followed the philosophy that not only 
 was laboratory work necessary, but the 
 resulting equipment must also be sub- 
 jected to in-mine, on-vehicle testing so 
 as to properly debug the hardware and 
 demonstrate its effectiveness. 
 
 Simple solutions were evaluated, such 
 as the extensive use of whiplike antennas 
 to serve as warning devices (fig. 5), but 
 only temporary attention was given to 
 these flags by haulage truck drivers. 
 The next step was to develop a family of 
 devices that could be retrofitted to the 
 haulage truck itself to improve the 
 driver's f ield-of-view. This complete 
 system, consisting of improved right- and 
 left-hand mirrors , ruggedized closed- 
 circuit television, and fresnel lens 
 blind area viewers (fig. 6) , improved the 
 driver's f ield-of-vision significantly 
 (fig. 7). The most important component 
 
 of the system was the front-right-mounted 
 viewer. It allowed a direct view of a 
 truck's most collision-prone area (fig. 
 8) . The viewer combined the downward- 
 looking ability of a flat fresnel lens 
 (the grooves bend the light like a prism) 
 with glare control louvers to keep in- 
 coming light from blinding the driver 
 (fig. 9). 
 
 This first-generation improved system 
 prototype was taken to Kaiser Steel's 
 Eagle Mountain Mine near Palm Springs , 
 Calif., in 1977 for a short-term test. 
 This evaluation involved mounting three 
 blind area viewers, a backup CCTV system, 
 and improved mirrors on a 170-ton- 
 capacity truck and operating the vehicle 
 for 1 week (fig. 10). The success of 
 this demonstration prompted the Bureau to 
 subject the prototype hardware to long- 
 term testing in three more mines in 1977 
 and 1978 (the Decker Mine in Decker, 
 Mont., the Erie Mine in Hoyt Lakes, 
 Minn. , and the Belle Ayr Mine south of 
 Gillette, Wyo.). Details of the testing 
 are shown in table 1. 
 
 TABLE 1. - In-mine testing of the first-generation improved visibility 
 system prototype hardware 
 
 Site 
 
 Haulage truck 
 
 Mine 
 
 Comments 
 
 
 capacity, tons 
 
 type 
 
 
 Eagle Mountain Mine, 
 
 170 
 
 Iron ore 
 
 3 viewers were used on front-right 
 
 Kaiser Steel Corp., 
 
 
 
 side of vehicle for full cover- 
 
 Eagle Mountain, Calif. 
 
 
 
 age. Also, a first-generation 
 CCTV was tried on back of truck. 
 
 Erie Mine, 
 
 100 
 
 Taconite 
 
 3 viewers, plus the CCTV and mir- 
 
 Pickands Mather & Co., 
 
 
 
 ror prototypes, were tried in 
 
 Hoyt Lakes , Minn. 
 
 
 
 this cold-weather environment. 
 
 Belle Ayr Mine, 
 
 120 
 
 Coal 
 
 3 viewers were tested on 2 trucks. 
 
 AMAX Coal Co. , 
 
 
 
 
 Gillette, Wyo. 
 
 
 
 
 Decker Mine, 
 
 120 
 
 Coal. . .. 
 
 Right- and left-hand prototypes, 
 
 Peter Kewit Co. , 
 
 
 
 plus the CCTV, were tested. 
 
 Decker, Mont. 
 
 
 
 
FIGURE 5. ■= Typical "whip" used in surface 
 mines to warn haulage truck drivers of the pres= 
 ence of smaller vehicles. 
 
 T V monitor 
 Left rear- 
 
 FIGURE 6. = Components of the improved vis- 
 ibility system for large haulage vehicles. 
 
 SECOND-GENERATION, LOW-PROFILE DESIGN 
 
 The blind area viewers were the most 
 viable component of the improved visibil- 
 ity system, so further work was initiated 
 to refine the hardware's design. Only 
 two major modifications seemed to be 
 needed. The first was to eliminate the 
 upward-looking portion of the fresnel 
 lens . It was originally thought that an 
 "all around" (i.e., fisheye) picture 
 through the viewer would help orient the 
 driver, but experiments showed that elim- 
 inating the top 3 in (i.e., the upward- 
 angled portion) of the lens did not im- 
 pair the vision. Instead, this reduced 
 the size of the viewer and reduced the 
 potential problem of sun glare in the 
 early mornings and evenings. 
 
 The second design modification was to 
 add a hood on the rear of the lens to 
 reduce backlighting (figs. 11-12). The 
 
 redesigned viewer was then demonstrated 
 at the contractor's facilities in San Ra- 
 mon, Calif. Figure 13 shows a mockup of 
 the front of a large haulage truck — note 
 the position of the man with the hat 
 standing in front of the truck mockup. 
 Figure 14 shows the man as seen through 
 the second-generation, low-profile blind 
 area viewer. 
 
 Besides the redesigning of the viewer 
 to the low profile, additional in-mine 
 testing was needed so the industry could 
 more fully understand the many applica- 
 tions of this unique device. To this 
 end, an evaluation program was extended 
 to various types of equipment in surface 
 mines, stone quarries, coalpits, and ura- 
 nium mines. Table 2 summarizes this 
 work. 
 
FIGURE 7. - Increased driver field-of-view with the improved system for large haulage trucks. 
 
 Area of visibility 
 improvement 
 
 Grade horizon 
 
 FIGURE 8. - Improved right=side visibility with the downward-looking blind area viewer. 
 
Lens 
 enclosure 
 
 Rubber 
 protector 
 
 Mounting 
 bracket 
 
 Lens 
 assembly 
 
 Lens retainers with 
 rubber molding 
 
 
 Fresnel lens 
 unit, 12 by Kin 
 
 Safety glass 
 
 Glare 
 
 control 
 
 louvers 
 
 FIGURE 9, = Components of the first=generation fresnel lens blind area viewer. 
 
 FIGURE 10. » ln=mine, on-vehicle test of first-generation prototype hardware (blind area viewers 
 are on radiator deck). 
 
TABLE 2. - In-mine testing of the second-generation, low-profile blind area viewers 
 
 Site 
 
 Equipment 
 
 Mine type 
 
 Hardware tested and comments 
 
 Eagel Mountain Mine, 
 
 100- and 170-ton haulage 
 
 
 First 3 viewers, then 1 far-right viewer, plus 
 
 Kaiser Steel Corp., 
 
 trucks. 
 
 
 improved mirrors. 
 
 Eagle Mountain, Calif. 
 
 
 
 
 Erie Mine, 
 
 3 100-ton haulage trucks.. 
 
 Taconite. 
 
 First 3 viewers, then 1 right-front viewer, 
 
 Pickands Mather & Co., 
 
 
 
 plus improved rearview mirror. 
 
 Hoyt Lakes, Minn. 
 
 
 
 
 Belle Ayr Mine, 
 
 
 
 Viewers. All 3 viewers were used in the oper- 
 
 AMAX Coal Co. , 
 
 
 
 ation, as blowing dirt and snow often limited 
 
 Gillette, Wyo. 
 
 
 
 visibility. 
 
 Minorca Mine, 
 
 
 Taconite. 
 
 1 right-front viewer, plus improved right- and 
 
 Inland Steel Co. , 
 
 
 
 left-hand mirrors. 
 
 Virginia, Minn. 
 
 
 
 
 Helena Quarry, 
 
 50-ton truck and 2 12-yd 
 
 Limestone 
 
 1 far-right viewer on truck, as well as view- 
 
 Vulcan Materials Corp., 
 
 loaders. 
 
 quarry. 
 
 ers on back of 2 loaders that worked in the 
 
 Birmingham, Ala. 
 
 
 
 plant area for stockpile loadout. 
 Successful. 
 
 Cyprus Pima Mine, 
 
 
 Copper. . . 
 
 First 3 viewers, then 1 right-front viewer, 
 
 Cyprus Mining Co., 
 
 
 
 plus improved mirrors. 
 
 Tucson, Ariz. 
 
 
 
 
 Bear Creek Mine, 
 
 120-ton haulage truck, 12- 
 
 Uranium. . 
 
 1 viewer on far-right side of each truck 
 
 Kennecott Co. , 
 
 yd front-end loader, and 
 
 
 and on rear of loader. 
 
 Casper, Wyo. 
 
 35-ton haulage truck. 
 
 
 
 Pinto Valley Mine, 
 
 
 Copper. . . 
 
 1 viewer on far right. Successful. 
 
 Cities Service Co., 
 
 
 
 
 Miami, Ariz. 
 
 
 
 
 Coteau Mine, 
 
 
 Lignite. . 
 
 1 viewer, plus improved mirrors. Successful. 
 
 North American Coal Corp., 
 
 
 Beulah, N. Dak. 
 
 
 
 
 Texas Quarry, 
 
 2 120-ton trucks and 12-yd 
 
 
 Viewers and mirrors. Successful. 2 blind 
 
 Flintkote Stone, 
 
 loader. 
 
 
 area viewers were destroyed and the mine 
 
 Hunt Valley, Md. 
 
 
 
 wanted replacement units immediately. 
 
 Glenrock Mine, 
 
 
 
 2 viewers. Successful. 
 
 Glenrock Coal Co., 
 
 
 
 
 Glenrock, Wyo. 
 
 
 
 
 National Steel Mine, 
 
 
 Taconite. 
 
 1 right-front viewer. Flood-lighting was 
 
 Hanna Mining Co., 
 
 
 
 tried successfully into the right-front 
 
 Keewatin, Minn. 
 
 
 
 blind area of the test truck. 
 
 Brownies Creek Mine, 
 
 2 85-ton haulage trucks... 
 
 
 1 viewer on far-right side. Successful. 
 
 Harbert Construction Co., 
 
 
 
 
 Pineville, Ky. 
 
 
 
 
 Highland Mine, 
 
 100-ton haulage trucks.... 
 
 Uranium. . 
 
 Viewers and mirrors. Drivers did not like 
 
 Exxon Minerals Co., 
 
 
 
 viewers, as they had to clean the glass too 
 
 Casper, Wyo. 
 
 
 
 many times; they did like mirrors. 
 
 Indianhead Mine, 
 
 120-ton haulage truck and 
 
 Lignite. . 
 
 Viewers on truck and 1 mirror on shovel. 
 
 North American Coal Corp., 
 
 loading shovel. 
 
 
 Successful. 
 
 Beulah, N. Dak. 
 
 
 
 
 Jackson County Mine, 
 
 
 
 Viewers. The first viewers were damaged by 
 
 Jackson County Iron Co., 
 
 
 
 vehicle vibration; replacement units (prop- 
 
 Inland Steel Corp. , 
 
 
 
 erly installed) are now properly operating. 
 
 Black River Falls, Wis. 
 
 
 
 
 Mauricetown Quarry, 
 Jessie Morie Co., 
 
 
 Crushed 
 stone. 
 
 Viewers. Working well on back of small 
 loaders. 
 
 
 Mauricetown, N.J. 
 
 
 
 
 Morenci Mine, 
 
 2 100-ton haulage trucks.. 
 
 Copper. . . 
 
 Viewers and mirrors. Drivers like improved 
 
 Phelps Dodge Corp., 
 
 
 
 mirrors, but cleaning viewers is a problem. 
 
 Morenci, Ariz. 
 
 
 
 
10 
 
 Glare control head 
 
 Tilt adjustment 
 
 Mounting bracket 
 
 Louvers 
 (glare control) 
 
 FIGURE 11, - Design of second-generation blind 
 area viewer. 
 
 Figures 15 and 16 show the second- 
 generation hardware at the Eagle Mountain 
 Mine in 1978. Three viewers were tried 
 on the 170-ton truck to get the maximum 
 f ield-of-view for the driver. After a 
 few months of testing, comments from 
 drivers led to a change in the layout and 
 just the far right-front viewer was used 
 instead of all three. This viewer cov- 
 ered the most dangerous blind area and 
 did not distract the driver's eyes as did 
 the forward-looking viewers during truck 
 movement. In fact, long-term use of this 
 single viewer proved to be the most ac- 
 ceptable, because drivers naturally turn 
 their heads to that side when turning 
 right and would look into the viewer. 
 The arrow in figure 16 shows the optimum 
 mounting location. 
 
 Long-term testing of the low-profile 
 hardware was also conducted on large 
 front-end loaders (FEL). Figure 17 shows 
 such an installation at the WIDCO coal 
 mine in Centralia, Wash. Figure 18 gives 
 the driver's view through the viewer. 
 
 FIGURE 12. = Second=generation blind area viewer, 
 
11 
 
 FIGURE 13. = Mockup testing of the second-generation blind area viewer. 
 
 FIGURE 14.- View through the second*generation 
 bl incl area viewer during the mockup testing. 
 
 During in-pit loading the drivers did not 
 use the viewer, but once they brought 
 their loaders into the plant area, the 
 ability to see the rear blind area was 
 greatly appreciated. The mine has had a 
 number of near misses because of the 
 heavy foot traffic and congestion in the 
 plant and maintenance shop areas. 
 
 RELATED WORK ON COLLISION PROTECTION 
 OF MINE EQUIPMENT 
 
 The blind area viewer has been gaining 
 wide acceptance by the mining industry, 
 but it is only part of the solution to 
 the problem of collision protection in 
 surface mines. The viewer is simple and 
 relatively maintenance free (it needs oc- 
 casional cleaning as does any vehicle's 
 mirror), and it is inexpensive, thus cost 
 effective. Current Bureau work is now 
 concentrating on answering two related 
 questions: (1) What motivates a driver 
 to look in the viewer so he/she can take 
 action to avoid a potential accident, and 
 
12 
 
 FIGURE 15 c = Initial in=mine testing of second=generation blind area viewers (indicated by arrows) 
 on a 170=ton=capacity truck, 
 
 (2) what might prevent 
 backing-up collision. 
 
 the close-in, 
 
 The improved right- and left-hand mir- 
 rors recently developed by the Bureau 
 allow much better rear vision, but small 
 vehicles still get into a truck's rear 
 blind area. The improved left-hand mir- 
 ror is a quick-change, 20- by 10-in flat 
 mirror, and the right-hand mirror is a 
 novel 30-in-radius , rectangular-convex 
 device. Both mirrors, plus the right- 
 front mounted viewer, are recommended for 
 use on trucks today and are commercially 
 available. Electronic devices could be 
 used to warn drivers of potential colli- 
 sions, but while many radar, infrared, or 
 sonic devices are small and inexpensive 
 enough for on-vehicle use, most are not 
 rugged enough for the harsh mining envi- 
 ronment. An electronic system for com- 
 plete collision protection is still a few 
 
 years away, but close-in sonic detectors, 
 now being modified by the Bureau (fig. 
 19), seem to have great potential. This 
 is especially true when the detector is 
 combined with the blind area viewer and a 
 voice warning system in the cab, to warn 
 the driver that something is either in or 
 approaching the blind side. Laboratory 
 work on such hardware is now being con- 
 ducted by the Bureau. 
 
 A direct view of the rear ground area 
 and dump point or beam is possible via 
 CCTV hardware. The Bureau is currently 
 evaluating this alternative (fig. 20), 
 but such systems are relatively expensive 
 and require extensive maintenance. Mines 
 with very hazardous dumping conditions 
 (such as a high waste dump over the side 
 of a mountain) are cooperating with the 
 Bureau to perfect CCTV-lighting technol- 
 ogy. As a result of this work, the price 
 
13 
 
 FIGURE 16. = On-truck testing of three viewers. Optimum location of a single viewer on a large 
 truck is at the right front, as indicated by arrow. 
 
 of a reliable system has dropped from design and in-mine testing of automated 
 
 about $60,000 to about $5,000 per vehi- 
 cle. Future work with ruggedized CCTV 
 applications will use newly developed 
 hardware in the $500 to $1,000 range. 
 Other longer term work involves the 
 
 backup warning devices and driver alert- 
 ness monitors, plus the creation and 
 evaluation of novel haulage truck designs 
 that eliminate many of the inherent dan- 
 gers in today's equipment. 
 
 COMMERCIALIZATION AND COST-EFFECTIVENESS ANALYSIS 
 
 Since May 1981, the Tracor MBA Corp. of 
 San Ramon, Calif., has been marketing 
 both the low-profile blind area viewer 
 and the improved mirrors. About 1,000 
 units have been sold, many to foreign 
 countries. The pricing of the hardware 
 varies according to the quantity ordered. 
 
 Assuming one right-front-mounted blind 
 area viewer on medium-sized trucks (i.e., 
 up to 150-ton capacity) and one far- 
 right-side plus a right-front viewer 
 for vehicles in the 170-ton-plus class, 
 a payback period of about 1 month is 
 
14 
 
 FIGURE 17. - Testing the viewer on the back of a large front=end loader. 
 
 obtained. This calculation assumes a 
 cost of $500 per viewer and considers 
 such factors as an ownership and operat- 
 ing cost of $175 to $200 per hour for 
 a 170-ton truck and only a 1-pct improve- 
 ment in haulage truck productivity 
 because of better driver vision (a real- 
 istic figure based on the Bureau's in- 
 mine test program). One percent of $200 
 is $2 per hour; thus the viewer cost 
 installed — $1,000 — is returned in 20 
 working days. 
 
 Tracor MBA will send marketing informa- 
 tion to any interested party. A number 
 of mines are now ordering new vehicles 
 with viewers already installed; thus, 
 retrofit action is not needed. A new 
 company, Optical Science Group of Peta- 
 luma, Calif., initiated a marketing ef- 
 fort in late 1982 to sell a smaller ver- 
 sion of a fresnel lens viewer called 
 Safe-T-Site, which costs substantially 
 less than $500 per unit. 
 
 FIGURE 18. = View of a car through the blind 
 area viewer on a large front-end loader. 
 
15 
 
 Sonar coverage area 
 
 Sonar coverage area 
 
 FIGURE 19. - Close-in collision warning device. 
 
 FIGURE 20. - Prototype CCTV rear-viewing system in an Arizona copper mine. 
 
 SUMMARY 
 
 Fresnel lens blind area viewers improve 
 not only mine safety but also equipment 
 productivity. This novel device was de- 
 veloped and in-mine-tested by the Bureau 
 through complementary in-house and con- 
 tract R&D. It is commercially available 
 and has a payback period of about 1 
 month. Blind area viewers are applicable 
 not only to haulage trucks, but also to 
 
 large front-end loaders, downhole drills, 
 draglines, power shovels, etc. During 
 in-mine testing of prototype viewers, at 
 mines where the viewers were installed 
 properly and drivers were told what to 
 expect, there was a positive response 
 from the drivers and an estimated 1- to 
 5-pct improvement in maneuverability. 
 
 INT.-BU.OF MINES, PGH., PA. 27130 
 
96 
 



 

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