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7
Safety of Heavy Vehicles
HIGH-LEVEL TECHNICAL TARGETS AND TIMETABLES
Introduction
The vision of the 21st Century Truck Partnership (21CTP) is that the nation’s trucks and buses safely and cost-effectively move larger volumes of freight and greater numbers of passengers while emitting little or no pollution and dramatically reducing the dependency on foreign oil. Safety is a vital element of the program. The U.S. Department of Energy (DOE) transports hazardous materials across the nation in large trucks. Ensuring the safety of these special trucks is critically important to DOE’s mission. However, the majority of the 21CTP budget is devoted to energy efficiency and vehicle emissions reduction, and only a relatively small portion has been dedicated to safety-related technology.
Recent reductions in the overall 21CTP budget (discussed in Chapter 1) have limited the funding provided by DOE for safety research going forward. As such, DOE relies on the Department of Transportation’s (DOT’s) initiatives for progress in the area of truck safety, since DOT has historically had responsibility for transportation safety. Indeed, although DOE and DOT have worked collaboratively in certain areas with respect to truck safety, DOT has established a number of specific commercial truck safety goals, but these goals have been established independent of the 21CTP. Furthermore, DOT budget allocations in support of commercial trucks come from the various DOT agencies including the National Highway Traffic Safety Administration (NHTSA), the Federal Motor Carrier Safety Administration (FMCSA), and the Federal Highway Administration (FHWA), and are also independent of the 21CTP. Each of these DOT agencies has broad responsibility well beyond the goals of the 21CTP.
Consequently, the committee encountered some difficulty in addressing the subject of commercial truck safety. By virtue of the future DOE budget allocation, the 21CTP includes very little on truck safety. Yet, DOT goals for commercial truck safety support the 21CTP’s vision of truck safety. Therefore, as a compromise, the committee elected to use the DOT safety goals, and to review selected DOT projects that support them. Moreover, this review of DOT programs is at a high level, because it is beyond the scope of this study to provide an in-depth review of all the DOT programs covering commercial truck safety and safety regulation. The review is also restricted to projects related to on-board large truck technologies and systems. Nevertheless, the committee suggests future work and outlines areas in which DOE and DOT collaboration might lead to improvements in large truck safety. DOT defines a “large truck” as one with a gross vehicle weight rating (GVWR) of more than 10,000 pounds (which includes vehicles that may be known in other contexts as medium and heavy trucks).1 Finally, the committee notes that its discussion focuses mainly on large trucks due to the fact that the number of bus accidents and fatalities is much smaller in comparison.
Goals and Timetables
DOT has established several specific goals for commercial truck safety:
Reduce the fatality rate for heavy-duty trucks and buses to 0.160 fatalities per 100 million total vehicle miles of travel by 2011.2
Develop and implement technologies for better braking, rollover protection, vehicle position, and visibility enhancement:
Braking. Advanced braking technologies will be sought with the research goal of achieving a reduction of stopping distances by 30 percent from operational
1
Personal communication (e-mail), Tim Johnson, DOT, NHTSA, June 12, 2008.
2
Michael S. Griffith, FMCSA, “Federal Motor Carrier Safety Administration Safety Research Overview,” Presentation to the committee, Washington, D.C., February 9, 2007.
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speeds in appropriate platforms. Improvement in retention of braking ability during grade descents is desired.
Rollover. Reduce the incidences of heavy vehicle rollover through the application of advanced technology brake control systems and other complementing technologies.
Vehicle position. Develop and implement driver aid systems that promote safe following distance and inlane tracking.
Visibility enhancement. Develop and implement systems that provide the operator with 360 degree visibility (direct and indirect) in day and night conditions.
Work with tire manufacturers to improve truck tire performance and reduce tire debris. Incorporate tire advancements with improved braking technologies to achieve substantial vehicle handling improvements.
Determine the feasibility of enhanced occupant survivability in collisions (offset, frontal, and angle/ sideswipe) at differential speeds up to 35 mph between heavy vehicles and passenger vehicles weighing approximately 4,000 pounds. Also, improvements will be sought in truck occupant seat belt use rates by harmonizing restraint systems requirements to enhance comfort and, therefore, driver acceptability.
Research Priorities and Budget Allocation
The committee asked DOE and DOT to provide a list of projects and related funding, prioritized by potential impact on reducing fatalities and injuries relevant to large truck and bus accidents. This request yielded only partial project lists, prioritized at the agency level (NHTSA, FHWA, and FMCSA), with too little information to give an overall picture of the safety programs or their funding trends.3 As a result, it was not possible for the committee to integrate the patchwork of information to produce a clear picture of DOT’s safety programs relevant to the 21CTP. This is another reason the committee elected the approach of discussing the DOT safety program at a high level, as mentioned above.
The committee understands that individual agencies and departments have responsibilities far beyond the subject of large-truck safety. Yet it appears that there is no single integrated list of truck safety projects prioritized by potential benefit. The committee addresses that topic later in this chapter.
ACCIDENTS INVOLVING LARGE TRUCKS
Before discussing progress toward achieving these DOT safety goals, the committee first reviews heavy-duty truck and bus accidents, to characterize their general nature. It then discusses how such accidents lead to traffic congestion and slowdowns, whose ultimate impact is increased fuel consumption and vehicle emissions.
The Nature of Heavy-Duty Truck and Bus Accidents
The main focus of the committee’s discussion is large trucks, because they contribute to an overwhelming majority of accidents compared to buses. For example, in 2005 there were 5,510 fatalities due to accidents involving large trucks and buses, but 5,212 of those fatalities were due to large trucks (DOT, NHTSA, 2006a).
In 2004, 12 percent of the total number of highway fatalities involved large trucks (over 10,000 pounds gross vehicle weight), resulting in the death of 5,190 people (DOT, NHTSA, 2005a). In 2005 the number of fatalities due to large-truck crashes rose to 5,212, while another 114,000 people were injured in large-truck accidents (DOT, FMCSA, 2007a). In 2006, the number dropped to 5,018 fatalities (Transport Topics, 2007). Although the most serious results of highway accidents are the fatalities and injuries, there is also a significant cost to society associated with large truck and bus accidents. In one study, the medical costs, emergency service costs, property damage costs, lost productivity costs, and the monetized value of the pain and suffering incurred by the families of those who die or are injured due to crashes were used to estimate the total cost of accidents. It was found that on average, the cost due to a large-truck crash was almost $60,000, while the average cost due to an inter city bus crash was over $32,000, based on 2000 dollars (Zaloshnja and Miller, 2002).
Large trucks pulling semi-trailers (Class 8) accounted for almost two-thirds of the truck-involved fatal crashes in 2005 (DOT, FMCSA, 2007a). The majority of fatal accidents involved vehicle–to-vehicle crashes rather than single-vehicle accidents. In 2005, the causes of fatal crashes were (1) large truck rear-ending passenger vehicle, 5 percent; (2) passenger vehicle rear-ending large truck, 16 percent; (3) large truck striking passenger vehicle (other than rear-ending), 35 percent; and (4) passenger vehicle striking large truck (other than rear-ending), 38 percent (DOT, FMCSA, 2007a). However, it is noteworthy that in 61.4 percent of the large truck fatality accidents, the initial point of impact with the large truck was the front of the truck (DOT, FMCSA, 2007b, Table 42).
In fatal accidents involving heavy trucks and lighter vehicles, the fatality is most often an occupant of the lighter vehicle, due, obviously, to the size and weight differentials. For example, in 2005, 92 percent of the fatalities due to such accidents were the occupants of the lighter vehicle (DOT, NHTSA, 2005a).
Although the number of heavy-duty trucks involved in fatal crashes per miles traveled declined, the total number of large trucks involved in fatal crashes increased from 4,472 to 4,932 from 1995 to 2005, and the total number of fatalities increased from 2004 to 2005 as noted above.
3
DOE, FCVT, response to committee queries on safety issues, transmitted via e-mail by Ken Howden, March 27, 2007.
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Studies suggest that in many cases the accidents between light and heavy vehicles are caused by the driver of the smaller vehicle. According to data collected by the Federal Motor Carrier Safety Administration (FMCSA), DOT, passenger vehicle drivers accounted for 66 percent of fatal accidents involving large trucks (DOT, FMCSA, 2007a). In a study of 210 accidents reported in 2002 by the University of Michigan’s Transportation Research Institute (UMTRI) (Hanowski, 2002), the results suggested that 78 percent of the accidents were initiated by the light-vehicle driver. Further, the study concluded that “[a]ggressive driving on the part of the light vehicle driver was found to be the primary contributing factor for light vehicle driver initiated incidents. For heavy vehicle driver initiated incidents, the primary contributing factor was poor driving technique.”
In another study of heavy truck accidents, Blower found that 70 percent of the truck-car accidents were cause by the driver of the car (De Groat, 1999). However, in a study of heavy truck accidents in North Carolina, Council et al. (2003) found a more even distribution of fault, reporting that across a broad spectrum of accident types, including accidents such as low-speed backing accidents, truck drivers account for slightly more accidents than car drivers: 48 percent for truck drivers and 40.2 percent for drivers of cars.
Accident causation has been a focus of research for many years. It is well known that for accidents leading to fatalities, considering all vehicle types—not just heavy trucks—alcohol or speeding are often causal factors, with alcohol involvement cited in about 40 percent of fatal accidents during the past 10 years, and speeding a factor in about 30 percent of fatal accidents over the same period of time (DOT, NHTSA, 2006a). However, alcohol and speeding are most often attributed to the driver of the vehicle other than the heavy truck (e.g., 22 percent of car drivers involved in fatal accidents were speeding while 7 percent of large truck drivers involved in fatal accidents were speeding). A recent report on large truck accident causation cites a variety of factors including driver fatigue, falling asleep, inattention, driving too fast for conditions, and physical impairment due to illness (DOT, NHTSA, 2006c).
Compared with heavy-duty trucks, the number of people killed in accidents involving medium-duty single-unit trucks is much smaller than the aforementioned case of large-truck accidents (300 fatalities in 2005 for classes 5 and 6 combined, for example) due to the fact that these medium-duty trucks typically operate at lower speeds, in an urban area, and during daylight (DOT, NHTSA, 2006c, p. 59).
Bus accidents account for a much smaller percentage of fatalities and injuries. For instance, in 2005, there were a total of 278 bus accident related fatalities, representing only 0.5 percent of all highway vehicle fatalities for that year (DOT, NHTSA, 2005a). Moreover, school-bus travel continues to be quite safe compared to travel in most other highway vehicles. Although any child fatality is a tragedy, from 1995 through 2005 on average only 21 school age children were fatalities in school transportation related crashes each year—of that 21, typically 6 were occupants of school transportation vehicles and 15 were pedestrians (DOT, NHTSA, 2005c, p. 1).
Impacts of Large-Truck Accidents on Fuel Consumption and the Environment
As described in the previous section, large truck crashes are a major cause of accident fatalities and injuries in the United States each year. That is reason enough for major efforts by industry and government to improve heavy truck highway safety. However, they also have direct impacts on fuel consumption and the environment. Accidents involving large trucks and buses create significant delays on our highways, particularly in congested areas. During these delays, there are increases in fuel usage due to travel at low speeds and while sitting in traffic at idle. There is a corresponding increase in tailpipe emissions during these times. In some cases, the accidents involve vehicles carrying hazardous materials, creating an even more dangerous situation, and in certain cases, potential issues related to national security.
Of course, accidents also contribute to costs associated with lost work time by commuters. Indeed, highway congestion, even in the absence of an accident, is a serious problem in the United States and in many large cities around the world. The Texas Transportation Institute (TTI) tracks congestion data for the 85 largest cities in the United States (http://tti.tamu.edu/). According to TTI, in 2003, in the combined total of the 85 cities, there was travel delay of about 3.7 billion hours, associated with which there was excess fuel consumption of 2.258 billion gallons of fuel. Elements contributing to congestion include heavy traffic, highway construction and repair, and roadway incidents including accidents (Texas Transportation Institute, 2007, Table 2).
A recent report prepared by the Volpe Center, DOT (Flieger et al., 2007), the authors provide estimates of the impact of commercial vehicle crashes on fuel economy and emissions. The authors project that each commercial motor vehicle (CMV) crash leads to additional fuel consumption of from almost 800 gallons to as much as 1,200 gallons depending on the level of congestion prior to the crash. Estimating extra emissions caused by CMV crashes is extremely difficult due to the variation of the factors involved. However, the Volpe report estimates that over a year, CMV crashes in the major metropolitan areas in the United States produce significant levels of emissions: CO on the order of 100,000 tons, and NOx on the order of 14,000 tons. Perhaps of more consequence, most of these emissions are localized in urban areas, thereby aggravating local health issues. Clearly, improvements in CMV safety will contribute to reduction in fuel consumption and exhaust emissions.
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GOAL 1:
REDUCE THE LARGE-TRUCK AND BUS FATALITY RATE TO 0.160 PER 100 MILLION TOTAL VEHICLE-MILES BY 2011
The information in this section clearly shows that large truck accidents are a very serious problem in the United States, causing major loss of life, thousands of serious injuries, and substantial property damage. Moreover, although some improvement has occurred since the highs of 1997, 1998, and 1999, the total number of deaths due to large truck accidents seems to remain in the neighborhood of 5,000 per year, and was higher in 2004 and 2005 than it was as long ago as 1994, as is shown in Figure 7-1. This trend is not unique to large truck accidents; highway fatalities due to all types of accidents have remained constant over the past decade. In fact, although the number of fatalities per miles traveled has decreased, the total number of fatalities has increased slightly from 40,716 in 1994 to 43,443 in 2005 (FARS data online).
On the other hand, there has also been a decrease in the rate of large-truck-related accidents as the number of vehicle miles traveled has increased steadily. Thus, improvements in highway safety have been observed. Figure 7-2 shows the fatality rate for large truck and bus accidents from 1995 to 2005. The fatality rate has declined from 0.215 to 0.184 during that time period while the total vehicle miles traveled
FIGURE 7-1 Deaths due to large-truck accidents. SOURCE: Data from DOT, NHTSA, Fatality Analysis Reporting System. Available at www.fars.nhtsa.dot.gov/ Accessed May 13, 2008.
FIGURE 7-2 Large-truck and bus fatality rate (per 100 million total vehicle miles traveled). SOURCE: Michael Griffith, DOT, FMCSA, August 29, 2007. Large Truck and Bus Fatality Rates, 1995-2005. Personal communication to the committee.
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has increased from 2,422,696 to 2,989,807, a 23 percent increase. As noted earlier, compared to bus accident related fatalities, large truck accidents contribute the most to highway fatalities by a large margin (~95 percent of fatalities).
Although the rate has improved, unfortunately, we have not seen a significant decrease in the number of large truck accident related fatalities in spite of the fact many resources have been directed at making improvements in vehicle safety. Earlier efforts were focused on crash protection, including improvements in structural crashworthiness and occupant protection. Increased usage of seat belts both in trucks and cars provides enhanced survivability. In light vehicles, the increased usage of air bags further enhances survivability in more severe crashes.
One might conclude that crashworthiness improvements have merely offset the increase in accidents due to the increase in total miles driven, and that we will have to reduce the number of crashes through accident avoidance technologies in order to significantly reduce the number of fatalities. To this end, DOT has been putting more focus on accident prevention. Crash avoidance topics relative to vehicle modifications include improvements in braking; rollover reduction; vehicle position (safe following, lane tracking); visibility enhancement; and tire safety.4 However, as the committee noted earlier in this chapter, most accidents are due to driver error. Moreover, in 2005 there were 14,539 car and truck fatalities due to crashes in which alcohol was a factor (DOT, NHTSA, 2006a). Therefore it will be important to assess the potential benefit of vehicle modifications to determine whether or not DOT’s goals for fatality rate reduction can be met.
Finding 7-1. The DOE program director of the 21st Century Truck Partnership has no direct authority for heavy-duty truck safety projects because there is no budget in the program itself to support safety projects. The program manager will need to continue to work with DOT, because DOT has several initiatives with the goal of making improvements in heavy-duty truck safety. They range from driver education to accident avoidance technology. However, the committee was unable to determine whether the goals would be met as a result of these initiatives.
Recommendation 7-1. DOT should develop a complete and comprehensive list of current and planned heavy-duty truck safety projects and initiatives, and prioritize them in order of potential benefit in reducing heavy-duty truck-related fatalities. The list should provide quantitative projections of fatality reduction potential attributable to each project. The list should also be used to prioritize budget and resource allocations, in order to expedite heavy-duty truck safety progress.
GOAL 2:
CRASH AVOIDANCE (E.G., BRAKING, ROLLOVER AVOIDANCE, VEHICLE POSITION CONTROL AND MONITORING, VISIBILITY IMPROVEMENTS, AND TIRE PERFORMANCE)
As mentioned above, it may be that we are seeing diminishing returns with respect to further improvements in crash protection; perhaps other, further benefits might come from 100 percent seat belt usage on the road. Crash avoidance has become, thus appropriately, the overarching next generation goal.
Programs
Braking
DOE and DOT are working toward improvements in braking to achieve a reduction by 30 percent in stopping distance, by considering the application of air disc brakes, more powerful front-axle brakes, and electronic control (DOE, 2006).5 In addition, work is ongoing at DOE laboratories to develop improved properties in brake materials.
The Department of Transportation is sponsoring several studies at DOE laboratories (DOE, 2006, p. 52). NHTSA has initiated several brake related studies at Oak Ridge National Lab (ORNL). A study on standardizing the rating of brake friction materials is aimed at maintaining standard capabilities in new and replacement brakes. Additional research is focused on testing brake materials on test tracks to correlate material properties with brake performance.
The Federal Highway Administration (FHWA) has initiated a study at ORNL aimed at improving the accuracy of truck brake simulations by incorporating the effects of temperature, humidity and braking torques on brake performance.
Rollover Prevention
The objective is to reduce the incidences of heavy vehicle rollover through applications of advanced braking systems and other technologies. NHTSA is working with industry using currently available commercial hardware to determine the effectiveness of roll stability systems and yaw stability control systems on tractors, and roll stability systems on trailers (Evans et al., 2005). In addition, NHTSA has sponsored work at the University of Michigan Transportation Research Institute on a hardware in the loop simulation study of electronic control systems, and has recently awarded an electronic stability control (ESC) driving simulator study to the National Advanced Driving Simulator at the University of Iowa.6
4
Tim Johnson, DOT, NHTSA, “NHTSA Heavy Vehicle Research Overview,” Presentation to the committee, Washington D.C., March 28, 2007, Slide 6.
5
Tim Johnson, DOT, NHTSA, “NHTSA Heavy Vehicle Research Overview,” Presentation to the committee, Washington D.C., February 8, 2007, Slide 6.
6
Tim Johnson, DOT, NHTSA, “NHTSA Heavy Vehicle Research Overview,” Presentation to the committee, Washington D.C., March 28, 2007, Slide 6.
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Vehicle Position Control
Research in this area includes studies of both forward collision warning to prevent rear impacts, and side-to-side lane departure warning. Both NHTSA and FMCSA have been heavily involved in research in these areas.7 In cooperation with industry, electronically controlled brake systems, collision warning systems, and adaptive cruise control systems are being evaluated to determine their effectiveness. In addition, on-board monitoring systems are being investigated to determine their effectiveness in alerting drivers who might become drowsy or distracted.
Visibility
According to NHTSA, one of the largest causes of large truck crashes results from lane changing and merging with other traffic. In many cases the accident is caused by the truck driver not being able to see areas that are blind spots. In cooperation with FMCSA, NHTSA is exploring the use of video mirrors to eliminate truck blind spots. Longer range potential research topics could include advanced night vision systems and head up displays, according to the 21CTP Roadmap (DOE, 2006).
Tire Performance
The objective is to work with tire manufacturers to improve truck tire performance and to reduce roadway tire debris (DOE, 2006). It will be important to couple tire behavior with improved braking technology to optimize vehicle stopping distance as well as handling. NHTSA plans to research improvements to FMVSS 119 relative to endurance and high speed tires, with emphasis on identification of the frequency and failure mode of both new and retread heavy vehicle).
Additional studies include methods for monitoring tire pressure and the effects of replacing standard dual tires with single tires on truck tractors.
In the area of tire mechanics, it is important for DOE and DOT to work closely together, to ensure that changes that lead to reduced rolling resistance don’t compromise safety.
Other Focuses
Improving driver performance is, of course, an important approach to preventing accidents. Driver fatigue has been cited as an important factor leading to accidents, and the National Transportation Safety Board has proposed the use of on-board recorders to ensure that drivers comply with rules regarding hours of service.8
The committee noted in this chapter that 7 percent of heavy truck drivers were speeding in accidents that led to a fatality. Some trucking companies employ speed control governors to prevent speeding. Reduced speed also reduces fuel consumption.
DOT’s Intelligent Transportation Systems Program (ITS) is broad in scope, touching on road design and operation, vehicle technologies, human factors research and in-vehicle as well as inter-vehicle communications.9 The ITS programs involve not only federal government agencies, but also heavy and light vehicle manufacturers, state and local governments, and contract research groups including universities.
The ITS program is beyond the scope of this report. However, we note that many aspects of ITS support the objective of accident avoidance. Furthermore, ITS is broad in vehicle scope, potentially covering communications among all highway vehicles; this could be an important element in helping to prevent large truck crashes with light vehicles.
It is also beyond the scope of this study to evaluate the work being done in support of our roads, bridges, and road infrastructure. However, the road system and its condition critically influence highway safety.
Progress Toward Goals
Braking
Several high-technology tractor-trailer trucks have been built that have demonstrated stopping distance reduction on the order of 30 percent. This result has been achieved using air disc brakes. The use of these brakes will also improve the fade resistance of large truck brake systems. Cost will be an issue with respect to rapid deployment (DOE, 2006, p. 1). In a DOT Field Operational Test (FOT) involving Volvo, test results validated the improvement in stopping distance using disc brakes, and also showed that the disc brakes have longer useful life compared with drum brakes (Volvo Trucks North America, 2005).
Rollover Prevention
In a field operational test involving six Freightliner tanker trucks, an in-cab system was evaluated. The system indicates to the driver what the rollover threshold is of the combination truck-trailer, and how close to that threshold the vehicle is at any instant in time. As a result of data analysis, it was concluded that the driver advisor system reduced the overall chance of rollover by from 20 to 30 percent for “too fast around the curve” types of potential rollover (DOE, 2006, p. 61).
7
Tim Johnson, DOT, NHTSA, “NHTSA Heavy Vehicle Research Overview,” Presentation to the committee, Washington D.C., February 8, 2007, Slide 4.
8
Mark V. Rosenker, “On-Board Recorders (EOBR’s) and Truck Drivers Fatigue Reduction,” Presentation to the U.S. Senate, May 1, 2007.
9
Michael F. Trentacoste, DOT, FHWA, “Safety R&D Overview,” Presentation to the committee, Washington, D.C., February 8, 2007, Slides 5 and 6.
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Vehicle Position Control
Two different field operational tests have been completed and provide results relative to vehicle position control. A field operational test in cooperation with Mack Trucks studied the performance of on-board lane departure warning systems. The Volvo FOT mentioned earlier included systems for collision warning, adaptable cruise control, and electronically controlled braking systems.10 According to DOT, the lane departure warning systems, under FOT conditions, provided a 21 percent to 23 percent reduction in accidents for single vehicle roadway departure, and a 17 to 24 percent reduction in rollovers (DOT, FMCSA, 2006). The Volvo FOT (Volvo Trucks North America, 2005) showed that it could be possible to reduce rear impacts by 28 percent by using a combination of collision warning, adaptive cruise control, and electronic braking.
Visibility
Performance specifications for camera/video imaging systems are expected to be completed in September 2007. In September 2008, the development and assessment of a 360 degree vision system capable of operating in all weather conditions should be completed.
Tire Performance
NHTSA is working with the American Society for Testing and Materials and tire companies on the aforementioned programs. Results are expected in 2007.
Researchers at ORNL have been studying the benefits of using a single tire to replace two thinner tires on heavy duty tractor trailer trucks. They have found that the single tire improves fuel economy by as much as 3 percent and also allows them to be run with more stability.11
Tire pressure monitoring systems are being developed to ensure proper pressures on truck tires. Keeping tires properly inflated maintains safety performance and improves fuel economy by reducing tire rolling resistance. In a study of light vehicle tires, it was found that a 10 percent reduction in average rolling resistance could yield a 1 to 2 percent improvement in fuel economy and that this could be done without sacrificing safety (NRC, 2006).
Summary of Performance
A number of programs are currently in progress to advance the individual goals of crash avoidance. These programs are in various states of completion, with some having reached milestones. During the past several years, large truck OEMs, working with suppliers, have developed on-board systems for enhancing roll and yaw stability, for improving straight line braking performance, for collision warning, and for alerting drivers relative to lane departure. In cooperation with DOT, many of these systems have been or are being evaluated in FOTs, and results are being reported.
Finding 7-2. Programs are underway to develop and implement technologies and vehicle systems to support safety goals. Indeed, private industry, through internal research and commercial product development, has produced commercially available systems for enhanced braking, roll stability, and lane departure warning. They are beginning to be used in the field. It is now important to determine to what extent these accident avoidance technologies will reduce the number of accidents and therefore fatalities and injuries.
Recommendation 7-2. DOT should continue programs in support of heavy-duty truck onboard safety systems, with an emphasis on accident avoidance and with priorities set by a comprehensive potential cost/benefit analysis (Recommendation 7-1). Particular emphasis should be placed on monitoring the accident experience of heavy-duty trucks as these systems begin to be deployed in the field (for example, as electronic stability control systems begin to penetrate the fleet). It is the role of the manufacturers to develop safety systems for commercial application. DOT can play important roles in (1) providing support for field tests (known to DOT as field operational tests), (2) monitoring field data to help substantiate benefit analyses used to prioritize resources, and (3) implementing regulations that would require the adoption of safety systems that were proved to be effective. With adequate field data, DOT should refine and more rigorously specify and prioritize goals for accident avoidance technologies.
Appropriate Roles for DOT in Accident Avoidance Technology Development and Deployment, and Other Areas of Vehicle Safety
The Department of Transportation plays an important role in large truck safety by establishing safety requirements for new vehicles, by licensing commercial drivers, and by ensuring that safe practices are used once the vehicles are in service. In addition to this regulatory role, DOT can promote highway safety by working with original equipment manufacturers, suppliers, other government agencies, including DOE, and others in helping to evaluate the effectiveness of newly developing large truck safety systems. The field operational tests are an example of how DOT is currently doing this. Furthermore, DOT can play an important and unique role by monitoring the field performance of truck safety systems to accurately assess the cost-benefit of such systems and by identifying any deficiencies in the systems. Finally, DOT can monitor safety initiatives and practices
10
Tim Johnson, DOT, NHTSA, “NHTSA Heavy Vehicle Research Overview,” Presentation to the committee, Washington D.C., March 28, 2007, Slide 6.
11
See www.greencarcongress.com/2006/06/single_widebase.html.
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around the world, and use this information along with its own studies to suggest future work that might further the goals of highway safety.
GOAL 3:
CRASHWORTHINESS RESEARCH (SURVIVABILITY)
The crashworthiness of heavy duty trucks is an area in which close collaboration between DOE and DOT is critical. Structural changes to the truck for weight reduction might be suggested for fuel economy savings as part of the 21CTP. It must also comprehend how the application of lightweight materials would affect the structural crashworthiness of the vehicle. Any modification to the exterior shape for improvements in safety could also affect the aerodynamic performance of the vehicle and thus its fuel efficiency. As a specific example, it was noted (DOE, 2006) that the addition of the rear under-ride guard to truck trailers adversely impacted the aerodynamic performance by increasing vehicle drag.
In addition to considering the crashworthiness of the heavy truck for the sake of protecting the truck driver, DOT should further explore the truck design from the standpoint of its aggressiveness in a collision with smaller vehicles. As the committee noted in the section entitled “Accidents Involving Large Trucks,” more than half of the fatal accidents in which a heavy truck collided with another vehicle involved contact with the front of the truck, suggesting this as an area for additional study with respect to alternate materials and under-ride guards.
Finding 7-3. In spite of extensive improvements in light vehicle crashworthiness made during the past decade, the number of fatalities caused by heavy-duty truck accidents has remained nearly constant, at approximately 5,000 per year, although the fatality rate has decreased showing that progress is being made. In most cases, the occupant(s) of the light vehicle is the one fatally injured. It appears that to make significant safety progress, it will be necessary to reduce the number of accidents substantially by implementing accident avoidance technologies as well as methods for improving driver behavior. In light of this need, DOT future plans have been directed largely at accident avoidance technologies.
Recommendation 7-3. The committee agrees with the apparent decision by DOT to put more emphasis on accident avoidance technologies than on additional crashworthiness research. In addition, DOT should continue to focus on driver education and law enforcement. Furthermore, DOE and DOT should work collaboratively, because there often are trade-offs between vehicle safety and fuel economy, for example, as new fuel efficient systems emerge. There are obvious trade-offs between safety and fuel economy in many areas of research such as tire mechanics and braking (especially with respect to hybrid vehicles). Of course, any additional work in aerodynamics or weight reduction might alter the vehicle configuration and therefore its crashworthiness. Moreover, as new fuel efficient systems emerge, such as hybrid electric systems, and vehicles using alternate fuels including, for example, hydrogen, it will be imperative that DOE and DOT work closely to ensure continued progress toward more fuel efficient vehicles but without compromising highway safety.
BENEFITS OF 21ST CENTURY TRUCK PARTNERSHIP SAFETY RESEARCH
Due to the relatively large number of fatalities and injuries suffered as a result of large truck accidents, it is entirely appropriate to consider many different safety technologies—in fact it may require an integrated system of technologies to make a large impact on the problem. For example, NHTSA has shown that a 30 percent improvement in stopping distance due to enhanced braking capability, could lead to a reduction of 257 fatalities.12 Unfortunately, this represents only a 4.9 percent reduction in fatalities related to large truck accidents based upon the number of fatalities reported in 2005, illustrating the point that significant improvements in truck safety are still needed.
The aforementioned discussion raises the obvious need for the development of an analysis of the numerous safety technologies under consideration, to be used to prioritize projects and funding. FMCSA has provided a list of large truck safety systems being applied and their approximate retail prices.13
Roll stability control systems
Tractor based system: ~$500 above cost of traction control
Trailer based system: ~ $1,000-$1,500
Electronic stability control systems: ~$1,500-$2,100
Lane departure systems: ~$700-$1,500
Collision warning systems: ~$700-$5,000 depending on options
Continued development should bring down these costs over time. However, there is only cursory and incomplete information available at this time to indicate to what extent the incorporation of all of these and other safety technologies will lead to the overall safety goals for fatality reduction for large truck and bus accidents as set by DOT.
NHTSA has addressed the potential benefits of electronic stability control (ESC) systems applied to passenger cars, multipurpose vehicles, and trucks and buses with a gross vehicle weight rating of 4,536 kg (10,000 lb) or less. Based on crash data studies, NHTSA estimates that the use of ESC will reduce single-vehicle crashes of SUVs by 59 percent and
12
DOE, FCVT, response to committee queries on safety issues, transmitted via e-mail by Ken Howden, March 27, 2007.
13
DOE, FCVT, response to committee queries on safety issues, transmitted via e-mail by Ken Howden, March 27, 2007.
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reduce rollovers by 84 percent. Overall, the annual potential benefit of ESC applied to these vehicles is estimated to be 5,300 to 10,300 lives saved and prevention of 168,000 to 252,000 injuries in all types of light vehicle crashes (DOT, NHTSA, 2006b). No comparable analysis of the potential benefit of ESC applied to heavy trucks has been found. However, the fact that there are over 15,000 rollovers of commercial trucks each year accounting for 12 percent of fatalities (UMTRI Research Review, 2000) suggests that there is a large potential benefit. It is encouraging at this time that heavy truck manufacturers and component suppliers are making stability control systems available on new trucks.
In addition to the aforementioned systems, it would be helpful to have similar analyses of other technologies under consideration. For example, the ITS technologies, including vehicle-to-vehicle communications, will permit communication between large commercial trucks and passenger cars and trucks, perhaps leading to substantial reduction in accidents. But it is important to know what improvements in safety will likely come from these technologies.
In conclusion, a benefit analysis for any system under consideration should be developed to help prioritize the work, and to help speed up the introduction of safety systems. A technology roadmap showing the benefit of all technologies under development would be very useful in generating support for the large truck safety effort.
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