National Academies Press: OpenBook

Commercial Motor Vehicle Driver Safety Belt Usage (2005)

Chapter: Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use

« Previous: Chapter 6 - Commercial Driver Focus Groups
Page 25
Suggested Citation:"Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use." National Academies of Sciences, Engineering, and Medicine. 2005. Commercial Motor Vehicle Driver Safety Belt Usage. Washington, DC: The National Academies Press. doi: 10.17226/13838.
×
Page 25
Page 26
Suggested Citation:"Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use." National Academies of Sciences, Engineering, and Medicine. 2005. Commercial Motor Vehicle Driver Safety Belt Usage. Washington, DC: The National Academies Press. doi: 10.17226/13838.
×
Page 26
Page 27
Suggested Citation:"Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use." National Academies of Sciences, Engineering, and Medicine. 2005. Commercial Motor Vehicle Driver Safety Belt Usage. Washington, DC: The National Academies Press. doi: 10.17226/13838.
×
Page 27
Page 28
Suggested Citation:"Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use." National Academies of Sciences, Engineering, and Medicine. 2005. Commercial Motor Vehicle Driver Safety Belt Usage. Washington, DC: The National Academies Press. doi: 10.17226/13838.
×
Page 28
Page 29
Suggested Citation:"Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use." National Academies of Sciences, Engineering, and Medicine. 2005. Commercial Motor Vehicle Driver Safety Belt Usage. Washington, DC: The National Academies Press. doi: 10.17226/13838.
×
Page 29
Page 30
Suggested Citation:"Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use." National Academies of Sciences, Engineering, and Medicine. 2005. Commercial Motor Vehicle Driver Safety Belt Usage. Washington, DC: The National Academies Press. doi: 10.17226/13838.
×
Page 30
Page 31
Suggested Citation:"Chapter 7 - Ergonomic and Technological Factors Affecting Safety Belt Use." National Academies of Sciences, Engineering, and Medicine. 2005. Commercial Motor Vehicle Driver Safety Belt Usage. Washington, DC: The National Academies Press. doi: 10.17226/13838.
×
Page 31

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

25 CHAPTER 7 ERGONOMIC AND TECHNOLOGICAL FACTORS AFFECTING SAFETY BELT USE 7.1 BACKGROUND This chapter focuses on ergonomic and technological fac- tors that might affect driver choices to use safety belts. This section provides general background and perspective on the safety belts and how they are chosen for installation in com- mercial vehicles. The following sections describe an ergonom- ics assessment of current safety belt use, technological and human factors related to safety belt technology, evolving tech- nologies in safety belts and user-friendly design, and conclu- sions for consideration by the Partnership. The fundamental safety belt system in use in CMVs today is a 3-point system that came about in the 1980s. In addition to employing the usually expected driver-restraining lap belt, the 3-point safety belt system incorporates a shoulder strap which is fastened to the truck cab’s “B-pillar” support structure above and slightly behind the driver’s left shoulder (see Figure 7). Through the 1990s, in an evolutionary way, the 3-point safety belts underwent several design improvements. Since the mid- 1990s, 3-point safety belts have been adopted industrywide and are now considered standard equipment. Based on representation from six OEMs of commercial trucks, it appears that 90% of the largest and principal fleet trucks sold in the United States today are being equipped and installed with safety belts manufactured by one safety belt company. The precise market share of this manufacturer was not independently verified for this study, but it is clear that focus on this firm’s product is valid for considering ergonomic factors in the design of truck safety belts in the United States. Product engineers and sales representatives of this com- pany provided a technical presentation and demonstration of the design features and operation of their safety belts to the Partnership meeting held at FMCSA in April 2004. Techni- cal and sales representatives also met with the research team ergonomist for an interview session at the Freightliner Trucks facility in Portland, Oregon, in October 2004. There are other safety belt products available, but they are found less frequently in the U.S. long-haul trucking industry. Based on interviews with OEM representatives, the largest Class 8 truck manufacturers tend not to procure and install these other safety belts in trucks they sell, unless other brand name safety belts are specifically requested to meet a cus- tomer’s special order. An ergonomic evaluation of safety belts must include sig- nificant consideration of the choice of seats installed in the truck. Truck safety belts are mounted in conjunction with the particulars of each seat selected, because safety belt design must interact with the particular seat a driver is using. Seat design features of functionality, adjustability for best reach of pedals and controls, visibility inside and outside the cab, absorption or attenuation of whole body vibration (WBV), overall ease of use of the seat, seat comfort, compatibility with the safety belt design, and ease of seat care and mainte- nance, all are involved in the ergonomics and human factors considerations of selection, installation, and use of truck seats and safety belts. Because the ergonomics assessment in this study is pri- marily oriented to safety belts, the specifics of the many vari- eties of Class 8 truck seats and the numerous human factors and ergonomics considerations of seats per se are only men- tioned here insofar as they have a direct impact on safety belt design factors. 7.2 ERGONOMICS ASSESSMENT METHODOLOGY This section presents ergonomics and human factors engi- neering information as part of an assessment of the design and use of the safety belt systems more commonly employed in contemporary Class 8 trucks on the highways of the United States. Professional ergonomics standards, measurements, and seat evaluation guidelines (e.g., those established by C. M. Gross et al. at the Biomechanics Corporation of America, Melville, NY) (Gross 1996) were applied in the assessment. The methods followed were (1) to conduct a literature search of reports containing information on CMV safety belt design— in particular, to identify any human factors or ergonomics studies of the safety belts; (2) to examine and conduct an ergonomics inspection of a variety of Class 8 truck safety belts, safety-belt-to-truck-seat combinations, or interactions among the seats and safety belts—to perform an examination of the installation of safety belts in different varieties of Class 8 trucks; (3) to interview and witness in operation a variety of

26 CMV drivers who differed anthropometrically (body sizes, etc.) while the drivers wore or used truck safety belts; and (4) to highlight some newer design technologies for possible subsequent application to safety belt installations in Class 8 trucks. To study the different approaches employed in fielding Class 8 trucks, the research team ergonomist examined the interaction(s) of the 3-point safety belt with several alternative air-ride truck seat designs, with different-sized drivers, and in different kinds of truck cabs. The examination sampled about a dozen different truck driver seats-to-safety-belt combinations (i.e., different brands and models of trucks and different brands and models of truck seats). The ergonomics assessment was not an exhaustive one in that it did not include a comprehen- sive assessment of the numerous truck brands and models and seat brands and models available in the U.S. long-haul truck- ing fleets. The research team visited several OEMs to examine the installation of current seat and safety belt designs and to study differing approaches employed in fielding new Class 8 trucks around the United States. The staff engineer at the Truck Man- ufacturers Association (TMA) and a participant in the Partner- ship (1) coordinated with several key OEMs to arrange visits to their facilities to examine the installation of safety belts in different brands and models of new trucks and (2) facilitated discussion with OEM representatives on these topics. OEMs contacted included Freightliner, Mack, International Truck and Engine Corporation, and PACCAR (Peterbilt and Kenworth). During a visit to one of the OEMs, the research team ergonomist examined in-depth one particular new truck with some of the latest optional safety belt features installed. An on-the-road test ride and demonstration of the truck driver and passenger seats, and the safety belts accompanying them, was conducted as part of the ergonomics assessment. The truck included a modern air-ride seat. The seating arrangement in that truck included a 3-point safety belt (see Figure 8), com- plete with two optional features designed to enhance driver comfort in using safety belts: (1) a shoulder strap D-loop height adjuster (see Figure 9) mounted on the truck cab’s B-pillar that permitted the driver to select about 7 in. of stroke adjustment for shoulder strap placement to his/her preference and (2) a shoulder strap equipped with a safety belt latch in place that permitted drivers to insert an extra inch or two of slack in the shoulder belt for added comfort as the strap crossed the driver’s chest (see Figures 10 and 11). The 45-min on-the road demonstration ride included trav- eling at varying speeds, enacting random forced quick stops, driving around banking turns, roadway inclines and declines, and driving over substantially bumpy roads, railroad tracks, and so forth. In a truck static mode, ergonomic observations and measurements were made with three drivers: a medium-sized man, a large, tall man, a smaller-statured woman seated in the driver’s seat. In addition to visiting several OEMs, the research team also visited several truck carrier terminals and several public and commercially run truck rest stops in the states of Florida, Maryland, Oregon, South Carolina, and Virginia. At these locations, drivers were interviewed about their safety belt use. The research team’s structured interviews of CMV drivers and of fleet managers (see Chapters 3, 4 and 5) included ques- tions about safety belt ergonomics and comfort issues that could affect safety belt use. Figure 7. Three-point safety belt in a Class 8 truck. Figure 8. Safety belt viewed from lap connector.

7.3 RESULTS OF ERGONOMICS ASSESSMENT In general, the professional opinion of the research team ergonomist is that safety belts being installed in Class 8 trucks appear to be practical and functional. The belts effec- tively serve a large portion of CMV drivers (approximately 27 the 20th to the 80th percentile anthropometrically). However, it is the research team’s view that the design of universally used safety belts does not serve well the population of large, heavy-set, obviously obese drivers. Additionally, the shoul- der belt may rub or chafe the necks of small-statured drivers. These two design problems with the CMV safety belts are addressed in more detail in this chapter. It seems clear that over the past decade, industrial design and ergonomics work has been focused on making the over- all design of safety belts user friendly, incorporating flexibil- ity in facile ease-of-use design attributes, driver comfort features, and appropriate user-fit considerations. New safety belt designs include two features to make the placement of the lap belt and shoulder strap more flexible by (1) allowing for shoulder strap height adjustments on the B-pillar to accommodate larger or smaller drivers through installation of a shoulder strap D-loop height adjuster and (2) permitting the driver to adjust the amount of belt and strap tension and pressure, particularly of the shoulder strap against the driver’s chest and upper torso through use of a shoulder strap tension adjuster. However, most of the trucks examined during this ergonomics assessment either did not have these new features installed, or in many of the cases where they were installed, the drivers did not appear to use Figure 9. Shoulder strap D-loop height adjuster. Figure 10. Shoulder strap tension adjustment mechanism (unlatched). Figure 11. Shoulder strap tension adjustment mechanism (latched).

them. In some cases, it was obvious the drivers did not know how to use them until shown by the ergonomist. 7.3.1 Instruction on Care and Maintenance of Safety Belts The safety belt installation and user manual that the research team observed provided ample instruction and guidance on how drivers should use, care for, inspect (every 20,000 miles), and maintain their safety belts. Some OEMs incorporate por- tions of these instructions directly into the actual new truck owner’s driver manual issued when a new truck is purchased. Upon delivery of every new truck, a few OEMs also provide a VHS video tape illustrating operation and maintenance of the new truck; and these tapes also include proper safety belt instruction. 7.3.2 Driver Complaints with Safety Belt Features Several past surveys (e.g., Balci, Vertz, and Shen 2001) reported truck drivers complained that their safety belts got trapped in the cab door, twisted, cinched, or locked up; they found the buckle difficult to operate, requiring two hands to fasten or open; or safety belts were difficult to locate to put on or take off. Drivers claimed safety belts were difficult to manipulate or to wear, especially with heavy winter clothing on; or they complained the belt pulling was not smooth; or the belt became loose and slack over time; or the shoulder belt slipped off the shoulder. The research team found similar issues in the literature review and in field interviews. In dis- cussions with the research team, drivers complained that the belts (lap and shoulder) rubbed or chafed their skin, waist, shoulder, and neck. The research team ergonomist witnessed some of these complaints. However, the research team’s ergonomics assess- ment found no obvious safety belt design features that con- tributed to or made many (but not all) of these complaints a reality on a regular basis (day to day usage). The research team did observe that some drivers did not know how to use safety belts properly or how to take care of and maintain their safety belts. Both situations were encountered in this evaluation. 7.3.3 Need for Training in Proper Use of the Truck Safety Belts Truck drivers gave numerous reasons for choosing not to wear their safety belts. Many of those reasons were highlighted in the results of fleet manager and driver surveys in this syn- thesis. During the ergonomics assessment, the research team ergonomist, while interviewing CMV drivers seated in their trucks, encountered several instances where the drivers seem- ingly had little actual experience using or wearing their safety belts. In some cases, safety belts (even in rather used trucks) were hung neatly along the B-pillar, but the belt material exhib- 28 ited few “wear and tear” markings normally indicative of repeated use. The observation of a lack of understanding about how to use safety belts was found to be true in general through- out the interviews of approximately two dozen drivers. Thus, in addition to convincing drivers to regularly use their safety belts, it is apparent that more training on the proper use of the safety belts as they were designed to be used may be an important issue as well. 7.3.4 Physical Characteristics of Truck Drivers Using Safety Belts Some driver complaints regarding safety belt features are attributable to the huge variety of physical characteristics of the driver population (e.g., trying to accommodate a wide variety of anthropometric and biomechanical considerations of the driver population itself, that is, big drivers and small drivers). The ergonomics assessment notes that very large drivers, particularly very tall and heavy-set drivers, and those with very large waistline and chest measurements, are likely to have difficulties in comfortably using any 3-point lap and shoulder belt design. Additionally, small-statured drivers, particularly less than 30th percentile drivers, will have diffi- culties with the 3-point belt systems. For very heavy-set, “large-bellied” drivers, it is very diffi- cult to properly position the lap belt as recommended by safety belt designers: “2 to 4 inches below the waist, low on the lap, against the thighs, and tight against the hips—but never wear- ing it over the abdomen or stomach.” Such placement of the lap belt below the large stomach would cause the belt mate- rial to “cut” into the skin, the waist, and the abdomen; and undoubtedly it would be quite uncomfortable. Properly worn shoulder straps are supposed to cross the collarbone and fit snugly between the breasts. The research team ergonomist wit- nessed evidence that some larger drivers and some smaller drivers had troubles with proper, comfortable placement of the shoulder belt as well. The small-statured driver must contend with additional anthropometric compatibility issues. It is challenging for a small driver to properly adjust most of the air-ride seats so that he/she can comfortably reach the controls (especially pedals, gear shift lever, radios, instrument panel knobs) in the cabs of some Class 8 trucks. Therefore, selection of a seat for the small-statured driver is an important consideration. During an interview with an OEM design engineer, a small-statured woman (5 ft. 2 in. tall and 120 lbs) who also was a CDL holder, questions were raised about various ergonomic factors of seat and safety belt design as they affected small drivers. Before driving on the road, the small driver set the adjustable controls of the driver’s air-ride seat for needed positioning fore-aft and for height, and set the safety belt and shoulder strap for preference. Then as the woman explained, while driving over rough, bumpy roads, railroad tracks, and so forth, a certain amount of jostle and bounce would be experienced. This could have a disconcert-

ing effect on the small driver’s ability to control the vehicle or, at the very least, on the small driver’s ability to maintain continuous visual contact with the road in front of the vehi- cle. The seat lap belt might lock up or cinch tight; and the shoulder strap was likely to slide or rub against the driver’s neck and upper chest area in ways that most small drivers found uncomfortable. On the test ride in the truck, the research team ergonomist estimated that while riding over bumpy roads and over railroad tracks, the air-ride seat verti- cal stroke easily rose and fell through a range of anywhere from 3 to 6 in. in height. Although the description of the “bounce” of the air-ride seat pertains to larger drivers as well, the problem seemed more acute to smaller-statured drivers. 7.3.5 Seat, Safety Belt, and B-Pillar Placement in the Truck Cab An ergonomic evaluation of safety belts must include sig- nificant consideration of the choice of seats installed in the truck. There are several different seat vendors that supply air- ride and other seats installed in trucks, and there is no stan- dard combination included in all trucks supplied by the various OEMs. While installing various truck seats and safety belt combi- nations, there will be slight differences in functionality and the comfort aspects of the seats and of the safety belts (lap belts and shoulder harness strap). In part, these differ in each truck cab configuration as a function of where specifically the seat mountings are positioned in the cab, and with the structural design of the cab, in particular with reference to the B-pillar behind the driver. As these characteristics relate to a driver’s comfort in the use of the safety belts they can be attributed to these key variables, both of which affect the functionality of the safety belt and its relative comfort characteristics: • Precise positioning of the shoulder loop web-guide rel- ative to the seat back and • Additional features the OEM placed on the seat safety belt (e.g., shoulder strap height adjuster and shoulder strap tension adjuster), whether these were sold as stan- dard inclusions on particular truck models or installed as additional options at the special order request of the client (fleet or independent owner operator) purchasing the vehicle. When the B-pillar is farther back from the driver’s seat, the “angle of attack” of the shoulder strap to the seat must be modified through use of a strap height adjustment, or else the shoulder strap will cause discomfort to the driver during upper torso body movements to operate the truck. Addition- ally, the lap belt end brackets and the seat lower tether mount- ing brackets must be positioned accordingly for a B-pillar which is farther back from the driver. These positionings become a factor for the driver when he/she makes fore and aft and higher or lower adjustments in the seat. 29 The provision of the shoulder strap height adjuster and the shoulder strap tension adjuster features would seem to be “must have” design requirements to provide an ergonomically sound design of current safety belts installed with air-ride seats in Class 8 trucks. 7.3.6 Variation in Truck Safety Belt Installation and Other Factors This ergonomics assessment focused on safety belts. It did not exhaustively examine the combination of all major brands and models of Class 8 trucks and seats used. The following design, installation, and use variables pertinent to driver safety belt use were not evaluated: • Different truck models and configurations. • Different seat manufacturers’ designs. Did the use of the safety belt and shoulder adjuster mechanism differ or did its performance differ as a function of truck seat design? • Safety belt design differences, old seats versus new belts. 7.4 ADDITIONAL ERGONOMICS AND HUMAN FACTORS CONSIDERATIONS 7.4.1 Ride Quality and Comfort Factors In all motor vehicles, including Class 8 trucks, there are many seat design features that interact with the issues relat- ing to use or non-use of safety belts. Insofar as seat design affects drivers’ perceptions of ride quality, the seat design features also impact the likelihood of whether or not a driver will wear his/her safety belt, and if so, perceive that he or she is wearing it comfortably. Truck drivers seated in their cabs are exposed to WBV and are affected by seating dynamics (suspension, springs, verti- cal stroke, lateral movement, etc). The dynamic response of the seat can be the factor most easily used to control human exposure to WBV. Seats can increase as well as decrease vibration experienced in the driver’s position. 7.4.2 Interaction of the Air-ride Seats and Safety Belt Use Three-point truck safety belts are anchored to the truck cab B-pillar wall behind the driver’s left shoulder as he/she sits fac- ing the front of the truck. Consequently, when the air-ride seat bounces up and down on its suspension to dampen or attenu- ate the WBV exposure to the driver, the shoulder belt tends to chafe the neck and shoulder as the strap slides across the driver’s upper torso. Additionally, the lap belt may expand or contract, even tighten around the driver’s waist as the air-ride seat bounces up and down. This interaction of the safety belt (lap belt and shoulder harness strap) with the air-ride features

can be especially disconcerting to a very large, heavy-set driver who is attempting to wear his/her safety belt com- fortably. If during a bounce, or jostling around, the belts/straps cinch tight, this can become very bothersome to the driver, and it will warrant considerable driver complaints. 7.4.3 Quick Egress from a Truck Cab in a Crash Sequence One common reason for not wearing a safety belt given by truck drivers was their desire to have control over enacting a “quick egress” from the truck cab during a crash sequence. From a human factors and ergonomics perspective, there was a question as to how difficult that was or how time-consuming it was for drivers to unfasten their safety belts and extricate themselves from the cab. The research team did not find significant research data on this topic. 7.5 NEW TECHNOLOGIES FOR TRUCK SAFETY BELT COMFORT AND USER-FRIENDLY DESIGN Several new technological innovations are under consider- ation for use in Class 8 truck seat and or safety belt designs. Several designers of safety belts for trucks have worked on user-friendly design features to make them more comfortable to use. For example, some safety belts are being designed with a softer edge to the strap (belt) webbing or with different stitch designs to provide better energy load limiting (Clancy 2004). There have been experiments conducted on the use of electric retractors for the excess material of the belt when the driver permitted too much slack during use (Clancy 2004). Some safety belt manufacturers are working on improving belt rout- ing and improving the latch-plate-to-buckle interface design (Sickon 2004). Some safety belt designers use a low-friction D-ring for the belt to pass through on the wall anchor point, making the D-ring height adjustable. Some others are consid- ering illuminated buckles to make them easier to locate in a crash sequence or at night (Sickon 2004). Insofar as they involve additional ergonomics and human factors engineering principles, some of the technological approaches to subse- quent seat and safety belt design are outlined here. 7.5.1 Seat-Integrated Belts Eventually, truck seat designers might work with those who design safety belts to produce a safety belt system designed as an integral part of the seat assembly itself—the so-called Seat- Integrated Belt (SIB) design. SIBs are reportedly widely avail- able as a purchase option by OEMs in Europe, where a large percentage of the large trucks are of the Cab-Over-the-Engine (COE) design. This design is substantially different from the more conventional truck design commonly found in the United 30 States. According to Parker (1997), integrated safety belts were much more comfortable for drivers, particularly for those rid- ing on air-ride seats because in the older safety belt design, the belts were attached to the cab frame and rubbed the driver’s person as the seat moved up and down. Proper installation of SIBs in the United States would require modifications to existent truck cab design to strengthen the cab floor to support the SIB and seats would have to be designed to withstand the loading throughout the seat frame itself (Clancy 2004, Sickon 2004). The requirements for seat anchorage in Europe are only about half the strength require- ments of the U.S. market, and the design criteria for surviv- ability of higher speed crashes must be more stringent. Proper sled tests to verify design features and crash sequence charac- teristics would have to be accomplished. 7.5.2 Safety Belt Tensioners Typically, when a driver wears a safety belt, it is not worn tightly around the waist and upper torso (shoulder straps). During a crash sequence, it is important that the belts be immediately tightened to start absorbing the driver’s energy and slow down body movement (McNamara 1997a and b). Therefore, another relatively new design feature under study in passenger car safety belt design is the use of pre-tensioners for safety belts to automatically take up the slack in a belt in milliseconds at the moment of impact and thus couple the driver or seat occupant to the seat quicker during the crash sequence (McNamara 1997, Prentkowski 2004). One of the important functions of pre-tensioners is to help reduce femur load—the load one gets on the knees from being thrust into the instrument panel. They also provide additional protection in rollovers, because they keep the driver cinched down to the seat. In those vehicles, the pre-tensioners are sometimes acti- vated by the same electronic sensors as those used for air bag impact sensors (Prentkowski 2004, Gorton 2004, and Sickon 2004). There are three types of pre-tensioners—retractor pre-tensioners, buckle pre-tensioners, and lap anchor pre-tensioners—that are being evaluated for transfer from passenger cars to trucks (Prentkowski, 2004). 7.5.3 Airbags and Safety Belts in Trucks Safety belts perform another valuable role by keeping the occupant properly positioned in front of an airbag during a crash sequence (McNamara 1997). This is becoming more important as more OEMs offer air bags in their heavy trucks. For example, airbags can significantly reduce head injuries by preventing a driver who is wearing a safety belt from hitting his/her face on the steering wheel. Currently, installation of an air bag in front of the truck driver is available as an optional purchase on many of the newer trucks. Such driver air bags are designed to inflate only in high-impact, frontal collisions. If a driver is wearing

his/her safety belt properly, and his/her body is positioned with the back against the seat back, with the head upright, so as to maintain a safe distance from the inflating air bag, the air bag will provide additional protection to the driver in such severe frontal collisions. In the United States, widespread use of a SIB, the routine use of pre-tensioners, or universal use of airbags would require coordination and agreement among seat designers, safety belt designers, safety engineers, and the OEMs who routinely install such combinations in the trucks they sell. Ultimately, it will be incumbent upon customers to decide to buy such improved, but likely more expensive seats, safety belt combi- nations, and safety features like air bags. At this point in time, SIBs are considered to be a premium cost item in the U.S. trucking industry. Frontal air bags are considered optional on some trucks, and pre-tensioners are not yet widely embraced. 7.5.4 Adaptive Occupant Protection Systems Proponents of designing airbags for safer trucks are also examining the use of adaptive occupant protection systems in trucks including sensors that detect how big the occupant (truck driver) is, where he/she is in the seat, and whether or not the driver or a passenger is wearing his/her safety belt. Exploratory work continues on these features. 7.5.5 Safety Belt Use Warning Signals Automatic shoulder harness latching, use of auditory warn- ing chimes, flashing light reminders, or engine start interlock- out mechanisms have either been explored or implemented for 31 use in passenger cars (Howell et al. 2003, and personal com- munication with William Howell, November 2004). Some— like the automatic shoulder belt latch—were tried and later abandoned. Many of these technological innovations could be adapted from the passenger vehicle industry with only mod- est adjustments for trucks (e.g., auditory warnings and buzzers to remind drivers to put on the safety belt). However, given the differences of the Class 8 truck driver’s work expectations and differences in CMV driver culture characteristics, there does not appear to be significant activity throughout the truck- ing industry to either explore or implement many of these fea- tures into Class 8 trucks (Sickon 2004). 7.6 ERGONOMICS ASSESSMENT CONCLUSIONS The research team concludes the following regarding the ergonomic and technological issues relating to safety belt use by CMV drivers: • Technological efforts need to be focused on comfortable safety belt use by very large, heavy, even obese drivers and by small-statured drivers. • OEMs who produce and sell Class 8 trucks should con- sider adopting safety belt design features that permit comfort latches and height adjusters. • Educational efforts directed at drivers to understand safety belt comfort features should be intensified. • Further ergonomics and human factors research should be undertaken on the various design and interface vari- ables for different brands and models of trucks and seats and safety belts.

Next: Chapter 8 - Conclusions, Suggested Practices, and Recommended Research Needs »
Commercial Motor Vehicle Driver Safety Belt Usage Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB’s Commercial Truck and Bus Safety Synthesis Program (CTBSSP) Synthesis 8: Commercial Motor Vehicle Driver Safety Belt Usage identifies and documents motivating factors that influence commercial motor vehicle (CMV) drivers in deciding whether to wear safety belts and research and practices that address CMV safety belt usage. It also offers a review of ergonomic and human engineering factors in the design and use of safety belts in CMVs as well as approaches to facilitate safety belt use by truck manufacturers.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!