In 2015, large trucks (trucks with a gross vehicle weight rating of more than 10,000 pounds) were involved in 414,958 crashes that resulted in 116,000 injuries and 4,067 fatalities (Federal Motor Carrier Safety Administration, 2016). The AAA Foundation for Traffic Safety identified the potential of several large-truck advanced safety technologies (ASTs) as promising countermeasures to reduce these crashes. Advanced safety technologies may use sensors or alerts to warn a driver of a possible collision, actively assume control of a vehicle in situations where a driver does not react to the threat of an imminent crash, or improve driver and fleet management (e.g., monitoring vehicle safety systems and drivers’ hours-of-service status). Although some advanced safety technologies may be effective at preventing crashes, it is also important to know whether they are cost-effective, as this information may assist consumers in purchasing advanced safety technologies and/or government regulators in mandating their use. The objective of this research was to provide scientifically-based estimates of the societal benefits and costs of advanced safety technologies in large trucks (i.e., the impacts an advanced safety technology may have across the entire society if implemented) in order to (1) allow the Department of Transportation to make informed decisions related to potential regulations on advanced safety technologies, and (2) promote the adoption of cost-effective advanced safety technologies to motor carriers. To accomplish this objective, an in-depth literature synthesis of 14 advanced safety technologies was completed, an expert advisory panel informed cost and benefit estimations for all advanced safety technologies (based on the literature review and their experience and knowledge), and benefit-cost analyses were performed on selected advanced safety technologies. The advisory panel recommended the following four technologies for benefit-cost analysis: air disc brakes, lane departure warning systems, automatic emergency braking systems, and video-based onboard safety monitoring systems. This report presents the results related to air disc brakes. See other AAA Foundation reports for analyses of automatic emergency braking systems, lane departure warning systems, and onboard safety monitoring systems. Air disc brakes are a vehicle safety system that has garnered attention in the trucking industry and may show promise in reducing crashes and their associated injuries and fatalities. Air disc brakes have been widely adopted in Europe and are increasingly popular in the U.S. Air disc brakes are an alternative to the traditional drum brake. Although air disc brakes have been available for several decades, early adoption was slow due to the high price of early generation air disc brakes, incompatibility with drum brakes, and a number of design shortcomings (e.g., power screw with poor release, chrome-plated slide pins, brake pad attached to the brake caliper, single-piston design, and undersized brake rotors; Bendix, n.d.). Air disc brakes use air pressure on the brake chamber and an internal slack adjuster to move a power screw. This power screw applies pressure on the wheel’s disc with the caliper. Air disc brakes offer reduced stopping distance, reduced maintenance, and reduced frequency of maintenance compared to traditional drum brakes. The literature review identified four studies that estimated the efficacy of large-truck air disc brakes in reducing crashes. These studies found air disc brakes may improve large truck stopping distance by 30% and may reduce high-speed large-truck striking rear-end collisions by as much as 43.2%. It is important to note that these studies were performed before the National Highway Traffic Safety Administration’s 2013 rule that mandated improved large-truck braking performance (Federal Motor Vehicle Safety Standards; Air Brake Systems, 2013). Thus, the efficacy of the current generation of air disc brakes is likely significantly lower compared to those found in the published literature (i.e., lower relative to current generation drum brakes that are also required to meet the 2013 braking performance rule). Additionally, one published report provided costs associated with air disc brakes. This report identified the costs of air disc brakes to range from $536 per vehicle (air disc brakes on only the steer axle) to $1,308 (air disc brakes on all axles). An Expert Advisory Panel convened May 17, 2016, at the AAA Foundation for Traffic Safety headquarters in Washington, D.C. This advisory panel consisted of six individuals representing various aspects of the industry, including representatives from a commercial motor vehicle carrier, a trucking insurance company, the Federal Motor Carrier Safety Administration, National Highway Traffic Safety Administration, and an air disc brakes original equipment manufacturer. The panel also included an industry safety consultant. The purpose of this meeting was twofold: (1) to assist the research team in selecting technologies that require a benefit-cost analysis, and (2) to identify the appropriate efficacy rates and costs to be used in the benefit-cost analyses. Following this discussion, a benefit-cost analysis was recommended for air disc brakes, and upper- and lower-bound efficacy rates and costs were selected for air disc brakes. Unlike the other advanced safety technologies, the literature review did not uncover any recent (i.e., conducted after the National Highway Traffic Safety Administration’s 2013 rule) research for air disc brakes. However, the advisory panel recommended analyses for air disc brakes because effective braking is critical to preventing crashes, because the efficacy of many other advanced safety technologies relies on brakes that can minimize a large truck’s stopping distance. The four studies investigating the efficacy of air disc brakes in preventing crashes were conducted prior to the improved stopping distance mandate (Federal Motor Vehicle Safety Standards; Air Brake Systems, 2013). This improvement in stopping distance for all brake systems significantly impacts the efficacy of air disc brakes when compared to other brake systems. With this in mind, the advisory panel recommended reduced efficacy rates (compared with those reported in previous research) of 10% and 15% reduction in rear-end crashes. Additionally, the advisory panel recommended a cost of $1,308 per truck (when air disc brakes are installed on all axles) based on vendor feedback and Garrott and Dunn (2007). The benefit-cost analysis followed conventional methods used in similar studies (e.g., Hickman et al., 2013) to estimate the societal benefits and costs of implementing air disc brakes in the trucking industry. Societal benefits of air disc brakes associated with a reduction in crashes were compared to the costs of deploying air disc brakes across the entire U.S. fleet of large trucks. The benefit and cost factors considered in this study are discussed below. Benefit Factors: • Medical-related costs; • Emergency response service costs; • Property damage; • Lost productivity; • Monetized value of pain, and the suffering and quality-of-life decrements experienced by families in a death or injury. Cost Factors: • Hardware purchase, installation, and financing costs; • Maintenance costs; • Replacement costs; • Costs associated with training for drivers and managers. To assess the impact air disc brakes could have on reducing crash rates (and the costs associated with the systems), national crash databases were used to identify air disc brakes’ target population. These crash databases included the Fatality Analysis Reporting System (FARS) and the General Estimates System (GES). The FARS database was used to determine the number of fatal crashes and their associated fatalities and injuries, and the GES database was used as an estimation for injury and property damage only crashes. The GES database also was used to estimate the number of injuries as a result of injury crashes. Queries were developed for crashes relevant to air disc brakes and information was extracted for different vehicle types for a period of six years (2010 to 2015). When filtering the GES and FARS crashes, the research team carefully considered the scenarios where air disc brakes may have prevented the crash. Specifically, only large-truck rear-end crashes where the large truck struck another vehicle were selected. Additionally, the research team used the following GES/FARS variables to further limit crashes that may have been prevented by air disc brakes: pre-event movement, critical event, and first harmful event. Finally, all crashes that involved the use of alcohol or drugs by the large truck driver were eliminated. The complete list of GES/FARS variables may be found in Appendix B. The recommended efficacy rates were applied to 86.6% of crashes estimated to be preventable by air disc brakes, to account for vehicles with brakes that may be out of adjustment. This percentage was estimated based on the results of the Commercial Motor Vehicle Safety Alliance 2016 Operation Airbrake program inspections that found 12.4% of vehicles had brake violations (Transport Topics, 2016). The proportion of crashes potentially preventable by improved braking performance of air disc brakes was adjusted downward accordingly to account for the possibility that some proportion of trucks would have poorly maintained brakes, which would decrease the effectiveness of the air disc brakes. Two sets of benefit-cost analyses were performed for air disc brakes. The first set of analyses included retrofitting the entire U.S. fleet of large trucks. This approach assumed all new vehicles added to the fleet would be equipped with air disc brakes and old vehicles would be retrofitted. This analysis approach represented the scenario with the most benefits but also the highest costs. The second set of analyses used an annual incremental costs analysis approach. This approach assumed all new vehicles would be equipped with air disc brakes (starting in 2018) and did not include retrofitting existing vehicles. Societal benefits were assessed over the life of the vehicle. Analyses included only class 7 and 8 (gross vehicle weight rating greater than 26,000 pounds) combination unit trucks (CUTs). Additionally, separate analyses were performed to account for the rate of monetary discount, in the present value, of the cost and benefits in any future year. Following guidance from the Office of Management and Budget (OMB, 2003) analyses were performed using a 0%, 3%, and 7% discount rate. (Author/publisher)
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