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Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses (2008)

Chapter: Chapter Two - Results of Literature Review

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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
×
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
×
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
×
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
×
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
×
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Suggested Citation:"Chapter Two - Results of Literature Review." National Academies of Sciences, Engineering, and Medicine. 2008. Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses. Washington, DC: The National Academies Press. doi: 10.17226/14211.
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The objectives of the literature review include: • Addressing truck safety with an emphasis on the role of speed, • Examining the asserted benefits and issues associated with speed limiters, • Reviewing policy initiatives relating to speed limiters mandates, • Highlighting key industry policy positions, and • Analyzing the effectiveness of speed limiters in terms of published studies and industry surveys. SPEED AND CRASHES Background In 2006, 385,000 large trucks (gross vehicle weight greater than 10,000 lb) were involved in traffic crashes in the United States; 4,932 of these crashes involved a fatality. Within this population, a total of 4,995 people died and an additional 106,000 people were injured. Large trucks account for 3% of all registered vehicles, 8% of total vehicle miles traveled, 8% of all vehicles involved in fatal crashes, and 4% of all vehicles involved in injury and property-damage-only crashes. One out of eight traffic fatalities in 2006 resulted from a collision involving a large truck (2006 Traffic Safety Facts 2008). These statistics should be put in perspective, relative to the overall safety performance of truck drivers. Although the sta- tistical data does not provide a definitive answer on the relative safety impact of CMVs and the role of truck driver responsi- bility in crashes, several analyses concluded that the majority of truck drivers are safe, with a minority of truck drivers being responsible for a disproportionate number of safety violations and crashes (Hickman et al. 2005). Independent of these data, there is a public perception that the trucking industry is not as safe as it should be. The data that can be analyzed indicate that truck drivers have lower crash rates per million vehicle miles traveled than light vehicle drivers (Traffic Safety Facts 2003 2004). Nonetheless, light vehicles are extremely vulnerable when they interact with trucks because trucks often weigh 20 to 30 times as much as light vehicles (Insurance Institute for Highway Safety 2002) and trucks require 20% to 40% more stopping distance than do light vehicles (Heavy Truck Safety Study 1987). This is best illustrated by the statistic that more than three-fourths of multiple-vehicle fatal crashes 6 involving large trucks result in the occupant(s) of the other vehicle being killed (Traffic Safety Facts 2003 2004). Because of the higher mileage-related crash exposure of trucks and the higher relative crash costs associated with large truck col- lisions, there is a premium on making trucks, and truck drivers, as safe as possible. Annual average crash costs are more than four times greater for a tractor-trailer ($88,483 in 2000 dollars) than for a passenger car (Wang et al. 1999; Zaloshnja and Miller 2004). Speed and Crashes The relationship between increased speed and crashes has been well documented (Stuster et al. 1998), with the key cor- relation being speed and crash severity. Excessive speeding by drivers decreases a driver’s response time in an event and may increase risk as a result of speed-related increases in crash exposure. As cited by NHTSA in Traffic Safety Facts 2003: “Speeding reduces a driver’s ability to steer safely around curves or objects in the roadway, extends the distance neces- sary to stop a vehicle, and increases the distance a vehicle trav- els while the driver reacts to a dangerous situation” (2005, p. 1). Impact force during a vehicle crash varies with the square of the vehicle speed; therefore, even small increases in speed have large and lethal effects on the force at impact (Roads and Traffic Authority 2005). The FMCSA (2005 Large Truck Crash Overview 2007) reported that “speeding” (exceeding the speed limit or driving too fast for conditions) was a factor in 22% of the fatal large truck crashes. The recently completed Large Truck Crash Causation Study estimated that 22.9% of all large truck crashes and 10.4% of large truck/passenger car crashes could be coded as traveling too fast for conditions (Report to Congress . . . 2006). The risk associated with vehicle speed is illustrated by the estimated annual savings of 2,000 to 4,000 lives as a result of the nationwide reduction in the highway speed limit to 55 mph in 1974 (Waller 1987). When the national speed limit was later raised to 65 mph, the occurrence of vehicle crashes showed a marked increase (Evans 1991). A recent analysis by Patterson et al. (2002) of the repeal of the National Maximum Speed Limit in 1996 supported Evan’s (1991) data. Patterson et al. (2002) found that 23 states had raised their rural Interstate speed limits to 70 or 75 mph and modeled the number of vehic- ular fatalities on rural Interstates from 1991 to 1999 against the new speed limits in these states (e.g., 75 mph, 70 mph, or no CHAPTER TWO RESULTS OF LITERATURE REVIEW

7change). Vehicular fatalities in the group of states that had raised their speed limits to 75 mph and 70 mph were higher than expected as compared with fatalities in the states that did not change their speed limits. Similarly, a rigorous meta-analysis conducted by Elvik et al. (2004) included 97 different studies with a total of 460 estimates of the relationship between changes in speed and changes in the frequency of crashes or associated injuries and fatalities. Using the Power Model, this study assessed the relationship between speed and road safety. The study concluded there was a relationship between speed and the number of crashes and the severity of crashes. The data suggest that speed is likely to be the sin- gle most important determinant in the frequency of traffic fatalities; a 10% reduction in the mean speed of traffic is likely to reduce fatal traffic crashes by 34% and have a greater impact on traffic fatalities than a 10% increase in traffic vol- ume. These data include all vehicles and are not specific to large trucks. While traveling above the posted speed limit or driving too fast for conditions has been shown to increase crash exposure (i.e., risk), speed variance among vehicles sharing the same road has also been shown to be correlated with vehicular crash risk. Lower speed variance is associated with fewer crashes (Finch et al. 1994; Kallberg and Toivanen 1998). Compliance with speed limits decreases speed variability among vehicles, which is associated with decreases in the frequency of road collisions and the severity of bodily injury (NCHRP Special Report 204 . . . 1984; Waller 1987). Vehicles traveling the same speed have fewer interactions and make fewer lane changing and decelerating maneuvers in response to other vehicles. This has been shown to decrease interactions between vehicles thereby reducing crash risk. Speeding Trends by Truck Drivers Insurance Institute for Highway Safety (IIHS) (“Institute Supports Speed Limiters . . .” 2007) concluded that truck speeds are increasing on rural Interstates (pp. 5, 7): In New Mexico, where the speed limit for trucks is 75 mph, the proportion of large trucks exceeding 70 mph increased from 27% in 1996 to about 43% in 2006. The percentage exceeding 75 mph more than doubled, rising from 4% to 10%. Truck speeds also increased substantially in Nevada, which has 75 mph speed limits on rural interstates. The proportion of trucks travel- ing faster than 70 mph increased from 29% in 1996 to 41% in 2006. During the same decade, the proportion of trucks topping 75 mph jumped from 8 to 14%. The IIHS nationwide survey (“Institute Supports Speed Limiters . . .” 2007) indicated that 64% of drivers favor a speed limiter requirement for large trucks. More than three- quarters of respondents who favored speed limiters supported a maximum speed limit below 70 mph. More than 80% of drivers reported that speeding on Interstate highways and free- ways was a safety problem, whereas 40% of drivers reported that speeding was a “big” safety problem. COUNTERMEASURES TO SPEED-RELATED CRASHES It is evident from the literature that inappropriate speed is a con- tributor to crashes; however, traditional approaches to reducing drivers’ speed behavior have been somewhat ineffective. Enforcement, education, and training are the traditional and most widely used strategies for speed management. Although these secondary, and in some cases reactive, approaches can be effective to a certain extent, it may be more effective to directly control the vehicle’s speed. Commercial Vehicle Speed Limitation in Europe The first European Union (EU) legislation requiring speed limiters was adopted in 1992 for large vehicles and extended to smaller commercial vehicles in 2002. There is now a single standard for all trucks of more than 3.5 tons and a single standard for all coaches of more than nine seats (J.-P. Repus- sard, Directorate General Energy and Transport, Unit E3— Road Safety, European Commission, personal communication, Dec. 2007). According to the European Commission (Report from the Commission . . . 2001), speed limiters were introduced to improve safety and reduce environmental effects. The regu- lation was based on the following arguments: • Heavy commercial vehicles and motor coaches are equipped with large engines to provide them with suf- ficient power to ascend uphill slopes when loaded; how- ever, when not loaded or descending, the vehicles’ power output capability may be greater than that needed to oper- ate safely and if unrestricted could pose an excessive risk to vehicle performance in braking or tire performance. • Lower speed results in fewer road crashes and fewer casualties on roads. • Lower speed means reduced fuel consumption and vehi- cle emissions. • Driving at lower speed causes less wear and tear on the engine, brakes, and tires, thereby indirectly improving road safety and environmental performance. Speed Limiters in Commercial Vehicles Speed limiter devices have been around for decades. Virtu- ally all Class 8 tractors now come factory-equipped to limit speeds by means of a menu-programmable interface that can be code-protected to resist tampering by drivers. After-market speed limiter devices exist as well. Recent technological advances have allowed for the application of information technology and modern communications to provide greater

flexibility and broader possibilities to manage speed even in changeable situations (e.g., adverse weather conditions and different posted speed limits) (Varhelyi and Makinen 2001). A 2006 study by Cantor et al. investigated the adoption of safety technologies among the largest trucking firms in the United States. The study targeted the largest for-hire motor carriers as the authors believed these operations had the great- est financial resources to adopt emerging safety technologies. A total of 415 surveys were completed and returned; of these, 60.4% reported adopting vehicle speed limiters in their fleets. The responding firms included 52 LTL operations, 179 with truckload operations, and 131 with both LTL and truckload operations. Thus, the study indicated wide adoption of speed limiters among the largest for-hire trucking fleets. In 1991, NHTSA’s Commercial Motor Vehicle Speed Control Safety Report to Congress discussed devices available to control truck speed and their application in commercial fleet settings. The report was supportive of fleet applications of speed-monitoring and speed-limiting devices, but concluded that “there was not sufficient justification to consider requir- ing all heavy trucks to be so equipped. Problem size statistics suggested that the number of target crashes was low; for example, approximately 30 fatal crash involvements per year for combination-unit trucks. This small crash problem size, together with uncertainties regarding the potential for crash reduction, suggested that the benefits of mandatory speed lim- itation were questionable.” Beginning in 1992, heavy vehicles in the United Kingdom were required to use speed limiters. According to Haggar (R. Haggar, U.K. Department for Transport, personal com- munication, Nov. 2007) they found the introduction of speed limiters correlated with a significant reduction in the crash rate, as follows: When requirements for goods vehicles over 7.5 tons were intro- duced in the early 1990s the criticism was leveled that more vehicles travelling on motorways at the same maximum speed would reduce not improve safety. In fact this was not the case. The accident involvement rate on motorways (per hundred mil- lion vehicle kms) for all heavy goods vehicles (HGVs) increased from 18.5 in 1993 to 18.8 in 2005–a 2% increase. This is signif- icant, because traffic increased by 36% over the same period. These figures include accidents involving HGVs between 3.5 and 7.5 tons which were not (in 2002) required to be fitted with a speed limiter. The reduction in accidents for exclusively speed limited vehicles was significant. All articulated HGVs were speed limited after 1993 and the accident involvement rate for that vehicle class fell from 40 (per hundred million vehicle kms) in 1993 to 30 in 2005—a 26% decrease. Other contributing fac- tors may also have influenced that decline but speed limiters have apparently played a significant part. Speed Limitation in Passenger Cars Speed limitation in passenger cars has received significant attention, particularly in Europe. Prior studies were examined to identify areas of relevance to speed limitation in CMVs. 8 Comte et al. (2000) surveyed passenger car drivers’ atti- tudes with regard to speed limiters and found that respon- dents believed enforcement was more acceptable than speed limiters because it targeted those who excessively break the speed limit. However, they also indicated that enforcement was costly and ineffective and rated speed limiters as the most effective means for reducing speed. The concept of intelligent speed adaptation (ISA) for pas- senger cars has been studied extensively in Europe. These activities are reviewed in Intelligent Vehicle Technology and Trends (Bishop 2005), a comprehensive study describing active safety systems activities worldwide, including ISA developments, forming the basis for the following review. The research for the book was based on project publications and discussions with project officials. ISA calls for vehicles to be “aware” of the prevailing speed limit on roads and (at minimum) provide feedback to the driver when that speed is being exceeded or (at maxi- mum) limit the vehicle’s speed to comply with the speed limit. When ISA first entered the intelligent vehicle (IV) scene, it was considered an outrageous idea by those who saw the driver’s authority over speed as untouchable. At the same time, road safety experts were convinced that, if speeds were moderated, road fatalities would decrease. The concept that has gradually gained currency in Europe is of an advi- sory system that provides insistent feedback to the driver when the speed limit is being exceeded. A strong motivator for such a system has come from increased enforcement of speed limits (and stiff speeding fines) over much of Europe (notably France), such that drivers are more likely to wel- come a system that helps them avoid severe penalties. A brief review of ISA projects and applications in Europe is pro- vided here. Sweden Sweden pioneered the development and testing of systems to electronically assist drivers in maintaining the posted speed limit. The Swedish Road Administration (SRA) has been at the forefront of research aimed at reducing speeding as part of its Vision Zero initiative to completely eliminate road fatalities. SRA conducted a major research initiative from 1999 to 2002 in the cities of Umea, Borlange, Lidkoping, and Lund. Approximately 5,000 ISA-equipped vehicles were driven by 10,000 drivers. The purpose of the research was to study driver attitudes and use of the ISA systems, road safety, and environmental impacts, and define conditions for large- scale deployment of ISA. Using roadside transponders and global positioning systems (GPS)/digital map techniques, the research team implemented provision of posted speed limit information and over-speed warning functions. An active accelerator pedal was used to communicate speed information to drivers. As a result of the

9test deployments, speed violations were reduced. The results suggest that better road safety was achieved without length- ening travel times and ISA had an overall positive effect on the surrounding traffic. The results also showed that if every vehicle was equipped with ISA, a 20% reduction in serious road injuries could be achieved. Although user acceptance was high, most users thought ISA should be mandatory so that ISA-equipped cars did not “stand out” in the traffic stream by traveling at a slower (although speed-limit compli- ant) speed. SRA is currently developing new measures, such as instituting regulations for ISA, equipping the Swedish government vehicle fleet with ISA and encouraging private fleets to adopt ISA as a component of “Quality Assured Transport.” According to Svedlund (2007), it is more advantageous when ISA is introduced fleet-wide rather than in individual private cars. The advantages of fleet-wide implementation of ISA include: • Economic incentives: lower speeds result in less fuel consumption and lower maintenance costs. • Existing policies: compliant speeds can easily be adopted naturally into company policy. • Mapmaking: some carriers are route-bound such that it is not necessary to find speed limit maps covering a larger area. • Easier to integrate technology: this target group already has the equipment to a much larger extent than private drivers, such as a communication infrastructure, posi- tioning, and maps for fleet management. • Incentives to maintain the equipment: the benefits pro- vided by ISA compel commercial operators to adequately maintain their equipment as compared with personal car owners. • Greater willingness to pay: early, non-mass production systems are too expensive for private users. Commer- cial companies can see the system benefits sufficiently to invest in the systems. • Goodwill: statements of intent by transport companies declaring their non-tolerance toward drugs, alcohol, and reckless driving will, in combination with the use of alcolocks and ISA, clearly improve their image as a reliable business. • Monitoring: ISA systems can generate statistics useful for driver monitoring. Since the full-scale trial, Sweden has been working on a strategy for large-scale implementation of ISA. Part of their strategy focuses on the national quality-assured transport project, which helps transport providers and purchasers to provide quality-assured transportation from a road safety and environmental perspective. The initiatives undertaken by the SRA are intended to contribute to creating a market demand for safe and environmentally sound transports. Key focus areas are speed, alcohol and drugs, seat belts, safe vehicles, and harmful emissions. Svedlund (2007) reports that the ISA market is growing, with more than 1,000 systems installed thus far. France The French government conducted ISA experimentation and assessment to better understand driver acceptance and effects on driving behavior in a project called LAVIA: The French Project of Adaptive Speed Limiter. The key objectives of the LAVIA (Limiter Adjusting to the Authorized Speed) project, which was completed in 2006, were: • Assess user acceptance and usage patterns for ISA with several different functional approaches, • Assess changes in individual driving behavior, • Measure the reductions of speed or gaps with regard to the speed limits, • Measure system impacts on speed limit compliance as well as any detrimental effects (e.g., reduced vigilance), and • Assess through simulation the global collective impacts on safety using field testing data. A vehicle equipped with LAVIA identified the posted speed limit at any time within the region designated for the experi- ments. The authorized speed was encoded in an enhanced dig- ital map for every road within the defined area and location referencing was used to correlate the vehicle’s location with the posted speed limit on the road being traveled. The project made use of manual speed limiter devices already in production by Renault and PSA Peugeot Citroën. The speed limit information was used by the on-board controller to provide three different types of driver assistance: • Advisory system: the system was activated at the driver’s option. When enabled, a warning was displayed on the dashboard if the speed limit was exceeded. • Voluntary active system: the system was activated at the driver’s option. However, when activated, the throt- tle was under LAVIA control and the speed limit could not be exceeded. • Mandatory active system: the system was always active, with the throttle under LAVIA control. The speed limit could not be exceeded. A fleet of 20 vehicles equipped with LAVIA were assigned to 100 drivers in the Paris area for normal usage in a radius of 200 km around their homes. Thus, many different road types and substantial variation in posted speed limits were encoun- tered. Bishop (2005) reported results from the LAVIA project. A questionnaire of 1,000 drivers assessed driver’s opinions toward speed, safety, and speed limiters. Although there was broad agreement with the idea of ISA, only 31% of respon- dents favored having ISA in their car. However, Bishop (2005) concluded there was a strong potential to increase

driver acceptance of ISA through improved designs, such as consistency of speed limits across the region, maintaining the speed limit database, and addressing the complexities of dynamic speed limits. For large-scale deployment to be effec- tive, Bishop (2005) indicated that factors such as context- appropriate speed limits, up-to-date speed limit databases, and interoperability within Europe would need to be addressed. ISA–UK From 1997 to 2000, the British government funded a study to assess acceptance of ISA, implementation technologies, sim- ulation modeling to assess side effects, and user trials both in a driving simulator and on actual roads. The major conclu- sion from this project was that ISA, in its most compulsory and versatile form (i.e., a mandatory system that is capable of dynamic speed limits based on weather and other con- ditions), could achieve a 36% reduction in injury crashes across the United Kingdom and a 58% reduction in fatal crashes. Follow-up work ran from 2001 to 2006 and examined driver behavior with and without speed limiters activated. The project involved 20 ISA-equipped vehicles and 80 drivers. Tri- als began in early 2003 in four cities that represented both urban and rural driving. The systems relied on GPS/map-based speed information and speed control could be overridden by the driver. As of the writing of the report, results from these follow-up studies have not yet been published. Other ISA Projects Smaller-scale ISA projects have been conducted in Belgium, Denmark, Finland, Hungary, the Netherlands, and Spain. Results were similar to those outlined by Bishop (2005) in terms of driver acceptance and effectiveness in reducing speeding and speeding-related crashes. Relevance to Speed Limiters on Commercial Vehicles Although the work in passenger car ISA has been quite thor- ough, its application in CMVs is very different. First, pas- senger car drivers have different motivations and concerns when driving as compared with CMV drivers; that is, pas- senger car drivers subjectively assess their perceived costs and benefits relative to speed, whereas CMV operations focus more on quantifiable costs and benefits wherever pos- sible. Second, the ISA work cited by Bishop (2005) was almost entirely focused on reducing speeding on arterials and residential streets, whereas the emphasis for CMV speed lim- iters is on major highways. Even though local and short-haul CMVs operate on arterials and residential streets as well, the speed limits on those types of roadways are likely to be well below the CMV speed limiters set speed. Furthermore, much 10 of the challenge in deploying ISA relates to creating and maintaining a map database with accurate information of posted speed limits, an issue that does not relate to commer- cial vehicle speed limiters. The ISA studies reviewed by Bishop (2005) echo some of the concerns found with CMV speed limiters in the writ- ten survey (such as driver’s concern with unequal speeds compared with neighboring vehicles); however, there are significant differences between passenger car and CMV driver concerns regarding speed limiters that the written sur- vey addressed. Therefore, the results of the ISA work are not deemed to be of sufficient magnitude to have a strong bearing on the commercial vehicle speed limiter questions addressed in this study. ADVANTAGES AND DISADVANTAGES OF SPEED LIMITERS This section describes the literature’s perspective on the advantages and disadvantages of speed limiters, both objec- tive and subjective. The review leads the Study Team to con- clude that there is insufficient data to conclusively establish many of the claims, leading to extensive reliance on empiri- cal data and professional judgment of individual fleet safety managers and independent drivers. The resulting lack of “solid ground” fuels the policy debate discussed in the next section. Advantages Clearly, speed limiters have several potential safety benefits. They reduce the top speed of vehicles to a pre-set limit. Although this may reduce overall crash risk it is more likely to lessen the severity of a crash (Wilmot and Khanal 1999). Speed limiters also reduce speed variability, thereby reduc- ing lane change and deceleration maneuvers (Varhelyi and Makinen 2001; Toledo et al. 2007). Speed limiters have also been shown to reduce approach speeds at intersections, curves, and roundabouts (Varhelyi and Makinen 2001). However, there are also potential benefits beyond safety. Higher speeds are less fuel-efficient. Speed limiters have been shown to be fuel-efficient and could lead to substantial fuel savings (Guerrero 2006). Less fuel consumption means a reduction in greenhouse gas emissions (“Slow Speed Ahead?” 2006) and longer tire life (“Institute Supports Speed Limiters . . .” 2007). Industry expert Robert Inderbitzen of REI Safety Services estimates that, overall, speed limiters can produce a 10% to 15% cost reduction when limiting speeds to about 60 mph, with most of the savings coming from fuel, tires, and maintenance (primarily brakes) (R. Inderbitzen, per- sonal communication, Oct. 2007). According to Vermeulen and Klimbie (2002), a field test in the Netherlands involving 177 vans and 30 trucks between 3.5 and 12 tons estimated the fuel savings from speed limiters at an average of 5%.

11 Disadvantages Several concerns have been raised against the adoption of mandatory speed limiters in CMVs. One concern is the lack of a consistent set speed across the North American conti- nent. Differences in the set speed in Canada and the United States could lead to a competitive advantage for one country. For example, two different set speeds (63 and 68 mph, respectively) have been proposed in Canada and the United States. Thus, U.S. trucks crossing the border into Canada would have to modify the pre-set limit in their speed limiter to comply with Canadian regulations. This would cost U.S. drivers time and money (Guerrero 2006). Another concern is that the lack of potential income and independence may steer drivers away from trucking. Many drivers choose trucking as a profession because of the independence the job offers (“Slow Speed Ahead?” 2006). This would further compound an industry situation that already has a driver shortage. Interestingly, one safety concern relates to the inability to accelerate in risky traffic scenarios. Although this might be a legitimate safety concern, fewer than 2% of crashes and con- flicts use acceleration as an evasive action (Hyden 1987). Indeed, some have argued that drivers may be more likely to speed on roads that have a posted speed limit below the pre- set speed limit to make-up for lost time (Almqvist et al. 1991). However, there is no research to suggest this compen- satory behavior is likely to occur. One respondent in the writ- ten survey noted that some companies have a bonus speed program (i.e., 20 min in 8 h of extra speed to pass); this pro- vides the necessary acceleration in critical situations. This would appear to address the concern held by many drivers regarding their inability to accelerate in risky traffic scenarios. Others have suggested that slower truck speeds compared with the surrounding light vehicle traffic will result in more frequent and possibly sudden lane changes, which as noted earlier can be one of many factors increasing crash risk stem- ming from speed differentials. Lastly, improvements in fuel efficiency related to speed limiters could have a negative impact on transportation funding vis a vis reduced consumption of taxable fuels (Understanding Strategies . . . 2007). In the short- to mid- term, a fuel tax increase would be needed to offset any pol- icy changes that reduce fuel consumption, assuming that transportation funding needs increase at current rates. POLICY INITIATIVES TO MANDATE SPEED LIMITERS Europe has been more progressive than the United States in implementing speed limiting technology with its CMV fleets; however, there have been recent legislative proposals to mandate speed limiters in all CMVs in both Canada and the U.S. (Guerrero 2006; “Slow Speed Ahead?” 2006; “Institute Supports Speed Limiters . . .” 2007). European Situation When the European Commission required that speed limiter regulations be extended to new medium-size commercial vehi- cles, the Royal Society for the Prevention of Accidents (RoSPA 2001) objected to these new speed limiter regulations by stat- ing the following: There is no clear evidence to show how many accidents have been prevented by fitting top-speed limiters to [large commer- cial] vehicles. Although, it seems likely that this measure has helped to reduce speeds, and so helped to reduce casualties, it is unfortunate that the effectiveness of top speed limiters on large vehicles has not been properly evaluated. This lack of evidence also makes it difficult to assess the likely road safety benefits of the EC’s proposal to extend this requirement to lighter HGVs [heavy goods vehicles], buses, and coaches and to midi-coaches and minibuses. We also note that the fitment of top speed limiters may reduce speeds on trunk roads and motorways, but will have no effect on urban roads, or roads through rural towns and vil- lages, which have lower speed limits, and where driving at inap- propriate speed (rather than excessive) speed is the problem. The Regulatory Assessment shows that speeding by large vehicles is still a serious problem. Despite the existing requirement for top- speed limiters on the heaviest vehicles, more than 80% of HGVs and 50% of coaches and buses exceed the speed limits on dual carriageways, and on single carriageways well more than 60% of HGVs and 23% of buses and coaches exceed the limits. There- fore, while RoSPA would support the measures proposed, we do not believe that they will have any significant effect on casualty reduction. RoSPA believes that the ultimate aim should be to have intelligent speed limiters fitted to all road-going vehicles, including cars, although this is clearly a long-term aim that will depend on the results of on-going research and trials (p. 1). The RoSPA believed the speed limiter legislation would only be effective if it considered all vehicles and was not limited to new vehicles. This would prevent operators from keeping older vehicles on the road as long as possible to avoid regulation and inadvertently undermining safety. Australian Situation The current national regulatory framework to address speed- ing by heavy vehicles includes a requirement that heavy vehi- cles of more than 12 tons gross vehicle mass and buses of more than 5 tons gross vehicle mass must have a speed limiter fitted and be set to limit the maximum speed by acceleration to 100 km/h. The National Heavy Vehicle Safety Strategy 2003–2010 adopted by the Australian Transport Council (ATC) has a range of strategic objectives, including better speed management and improved heavy vehicle speed com- pliance. As part of its responsibility under this strategy, ATC reviewed regulatory approaches for improving heavy vehicle speed compliance. A number of options to help address speeding heavy vehicles were explored by the ATC, includ- ing an assessment of the costs and benefits of each option. Their selected proposed approach was to develop a chain of responsibility for speed compliance. Under this approach, each party in the transport chain who can influ- ence whether or not speeding occurs will have a measure of responsibility to ensure that the road transport task is carried out

by a driver in such a manner that does not require speeding. This would oblige all parties in the transport chain to take positive steps to prevent a breach of speed limits. This proposal attempts to deliver an improved culture of compliance with speed limits in the road transport industry (Heavy Vehicle Speed Compliance 2006, p. 16). The report also notes that chain-of-responsibility obligations relating to vehicle mass, dimension, and load restraint have been in place in some jurisdictions since 2005, resulting in increased compliance with road transport law. Although tampering has been an issue with speed limiters in Australia, it is significant to note that the non-technological chain of compliance approach has been recommended over another layer of technology to improve tamper resistance. Comments received in response to the Commission’s pro- posal were largely positive regarding this new emphasis on chain of compliance. North American Initiatives Recent legislative proposals in Canada and the United States may require all heavy trucks to be equipped with a speed limiter pre-set at a top speed. The Ministry of Transportation of Ontario recently reviewed a proposal introduced by the Ontario Trucking Association and Canadian Trucking Alliance (CTA) that seeks to limit the top speed of all heavy trucks in Ontario Province to 105 kph (or about 65 mph) (Guerrero 2006). The Ontario Trucking Association indi- cated this measure will increase highway safety and air qual- ity (Gillam 2006). This legislation was passed in June 2008; in Ontario 65 mph is now the maximum legal speed for trucks built after 1995. Further relating to the proposal from the CTA, federal, provincial, and territorial governments are examining the feasi- bility of requiring the activation of speed limiters on all heavy trucks operating in Canada. Transport Canada, on behalf of the provinces and territories, is currently undertaking a review of the implications of such a requirement from a safety, environ- mental, economic, and operational perspective. According to Spoerri (A. Spoerri, “Motor Carrier—Road Safety & Motor Vehicle Regulation, Transport Canada,” Truck Speed Limiter Project Workplan Status and Timetable, personal communica- tion, Dec. 2007), one study is using traffic modeling to investi- gate the impact of speed differentials and car–truck interactions on highway safety and crash risk, the results of which could be very useful to the safety dialogue going forward. Another study is assessing the experiences of for-hire, private, and owner–operator carriers. Results were due by spring 2008. According to the CTA (“Canadian Trucking Alliance . . .” 2007), several safety and environmental groups have pub- licly supported the proposal, including the Canada Safety Council, Pollution Probe, the Traffic Injury Research Foun- dation, SmartRisk, the Lung Association, the Canadian Transportation Equipment Association, and the Insurance 12 Bureau of Canada. The Owner–Operators Independent Driver’s Association (OOIDA) is a notable dissenter (see Opposition to Speed Limiters). Both NHTSA and FMCSA are reviewing possible rule- making on speed limiters. Two different proposals are under consideration. One proposal, led by Schneider National and a group of other carriers, asked FMCSA to require all Class 7 & 8 trucks to have a speed limiter set at 68 mph (even those currently on the road) (McNally 2006). The second pro- posal, submitted by the ATA, requests that all newly manu- factured trucks be equipped with a speed limiter set at no more than 68 mph (McNally 2006; “Institute Supports Speed Limiters . . .” 2007). NHTSA issued a request for comments (Docket No. NHTSA-2007-26851) in January 2007 to collect industry opinions regarding speed limiters. As of the writing of this report, NHTSA received approximately 3,700 responses to the docket. Supporters, including advocacy groups and truck fleets, cited both fuel economy and safety as key reasons to adopt speed limiters. Owner-operators represented a large portion of the opposing view, as outlined in the OOIDA response here. Opposition to Speed Limiters OOIDA (Johnston and Shapiro 2007) is perhaps the most vocal opponent of proposals to require certain CMVs to have speed limiters installed and set to 68 mph. OOIDA opposi- tion centers on safety, disputing the reported safety benefits. Key points of OOIDA’s position are: • The 68 mph speed limiter setting is impractical because there are 24 states with speed limits of 70 or 75 mph. • Trucks traveling slower than regular traffic create turbu- lence in the traffic flow, leading to increased lane changes and sudden braking, thereby increasing the potential for car–truck crashes. • Truck maneuverability is compromised in safety-critical situations, as there are times when greater power and speed are necessary, such as one truck passing another, merging onto a highway, or getting out of the way of merging vehicles. • Speed limiters are too rudimentary a safety tool, as trav- eling too fast for conditions, which can occur at any speed, is the speed-related behavior most commonly associated with truck crashes. OOIDA asserts that safe speeds in these conditions are far less than 68 mph. • There is no specific evidence to support the claimed fuel economy improvements of speed limited to 68 mph. Studies have shown that the increase in fuel efficiency would only be in the 0.08 to 0.03 mpg range. Instead, bet- ter aerodynamics would result in far greater efficiency. • Instead of speed limiters, it is more effective to focus on: – Improved training, including a graduated Commercial Driver’s License course, apprenticeship programs, and/or other forms of expanded driver training;

13 – More effective enforcement of existing speed laws; and – Changing the circumstances that induce drivers to speed, namely shipper and receiver scheduling de- mands and compensation based on the miles driven or loads hauled. OOIDA asserts the petitioners’ real motivation is to reduce competition for the limited pool of qualified drivers. OOIDA notes that many fleets that are members of the ATA use speed limiters and are seeking to remove driver concerns about speed limiters as an issue in the hiring process (i.e., if everyone has to have it, the ATA fleets will better be able to compete). ASSESSMENTS OF SPEED LIMITER EFFECTIVENESS Safety Effectiveness of Speed Limiters: Published Results This section discusses the effectiveness of speed limiters on driver behavior. Unfortunately, there is a paucity of relevant published research on how speed limiters affect driving behav- ior, particularly in terms of safety. As discussed in Appendix A, the search for published studies in this area was extensive, including searches of journal articles as well as direct contacts with government agencies in Europe and Australia. The studies identified that assessed truck driver behavior while driving a truck equipped with a speed limiter are not of sufficient detail to be helpful in this analysis of safety effectiveness. Other studies focusing on the passenger car population are somewhat relevant and are reviewed here. The European Commission (Report from the Commis- sion . . . 2001) report cites studies (not further referenced in the report) that have been made on the effects of the use of speed limitation devices on heavy commercial vehicles in comparison with vehicles not fitted with them, as follows: The studies differ slightly in their conclusions but the following overall positive effects are noted: lower fuel consumption (from 3% to 11%), lower maintenance costs (tyres, brakes, engine), increased road safety (fewer casualties), more relaxed driving and lower insurance premiums as a consequence of less acci- dents. As negative effects the following are noted: decreased road safety when performing an overtaking manoeuvre as over- taking another vehicle takes relatively longer, and increased delivery times as the journey takes longer to make. An indirect effect is that the long overtaking manoeuvres of vehicles fitted with speed limitation devices have the effect of reducing the average speed of other road users. To summarise, it is clear that the known effects of speed limitation devices are generally very positive for drivers, for companies, for society and for the envi- ronment. The negative aspects are small and avoidable: if all the speed limitation devices were set accurately to the same speed, there would be less need for overtaking, and as the use of speed limitation devices is accepted, the timetables given to the drivers are more realistic in comparison with the old practice of giving unrealistic timetables which, to be met, required speeding (p. 3). The Commission report (p. 6) also included statements offered by some member states regarding the road safety effectiveness of speed limiters on commercial vehicles. Danish authorities noted “the positive effect of speed limiter devices on road safety and the environment” but did not elaborate further on this point. Authorities in the United Kingdom stated that although some problems exist with tampering of the speed limitation device and thus more enforcement is needed, the overall results of the use of speed limitation devices are posi- tive, especially in lowering the average speed of buses and their accident and casualty rates. Unfortunately, although the Netherlands field test earlier assessed the effects of speed limiters on truck fuel consump- tion, maintenance costs, damage costs, and speeding tickets, safety was not addressed (Vermeulen and Klimbie 2002). Regarding passenger cars, Varhelyi and Makinen (2001) conducted field trials in the Netherlands, Spain, and Sweden with an instrumented car equipped with a speed limiting device. Different speed categories, ranging from 30 to 120 kph, were tested across the three countries. The speed limiter reduced driving speeds on roads with speed limits ranging from 30 to 70 kph; however, there were no significant changes on roads where the speed limit was above 70 kph. The authors concluded that heavy congestion and the prevailing speed below the posted speed limit contributed to the lack of significant results on roads where the speed limit was greater than 70 kph. Speed variances decreased significantly and approach speeds at roundabouts, intersections, and curves were slower with the speed limiter. Time gaps increased in the speed interval of 30 to 50 kph, suggesting safer car following behavior. These results suggest that the speed limiter had beneficial effects on driving behavior other than limiting the driver from exceeding the posted speed limit. Toledo et al. (2007) used a simulation-based evaluation of the impact of speed limiters on traffic flow and safety. In their model they estimated that 10% of the vehicles were equipped with speed limiters. They rationalized that this assumption corresponded to a policy mandating speed limiters in all CMVs. The impact of two pre-set speed limits, 100 kph and 120 kph, at various speed distributions and congestion levels was evaluated. The simulation showed that speed limiters may reduce average traffic speeds by as much as 10% and the variability of traffic speed may also be significantly reduced. Effectiveness of Speed Limiters: Industry Surveys Given the lack of controlled studies, information as to speed limiter effectiveness must be gleaned from the experiences of CMV fleet managers and drivers. The results of recent sur- veys performed by OOIDA and ATRI are reviewed here. OOIDA Foundation Survey OOIDA supports its opposition of legislation to mandate speed limiters with the results of a survey conducted by the OOIDA Foundation (Speed Limiter Survey Results Final

Report 2007). The survey was sent to 15,382 OOIDA mem- bers who were listed in its database as hired drivers. There were a total of 3,422 completed surveys returned, representing a 22.3% return rate. The respondents drive for 2,080 different trucking compa- nies, of which 60.8% of these companies already had speed limiters installed. The survey asked drivers whether, if all things were equal, they would rather drive for a company that does have speed limiters or one that does not. As many large carriers already have speed limiters installed in their vehicle fleets and often have better pay and benefits, it is often seen as a tradeoff, so the question addressed driver preference of driving with a speed limiter. Of 3,400 drivers, 2,780 (81.7%) reported that they would rather drive for a company without speed limiters, 120 (3.5%) would choose a company with speed limiters, and 500 (14.7%) said the issue was not a factor. The drivers’ primary concern with speed limiters was the lack of passing speed followed by increased congestion. Further, 80.8% of the respondents admitted they “some- times” exceeded the speed limit on roads or in areas where the speed limit is less than the speed limiter setting to make up for lost time. Generally speaking, the approach and response rate of the OOIDA study stands up well in comparison to similar studies. The response rate was very high for a mail survey. The study was useful in that it was addressed specifically to the 15,000 company drivers who are OOIDA members, excluding their remaining 141,000 members who are owner–operators. The CTBSSP Study Team did identify one area of concern: although the survey asked if the truck was equipped with a speed limiter (which most Class 8 trucks are), only 1,226 respondents answered the question regarding the top speed setting of the speed limiter, whereas 2,211 respondents indi- cated that their truck was equipped with a speed limiter. Because it is possible that the speed limiter is not active on an equipped truck, it remains unclear how many respondents were actually using the speed limiter. ATRI Survey Results In early 2007, ATRI conducted a web-based survey of motor carriers designed to collect information about speed limiter usage in large trucks (McDonald and Brewster 2007). The 14 240 respondents provided demographic details along with information on speed limiter installation rates, rationale for use, speed settings, and the impact of speed limiters on per- sonnel. ATRI considers the responses to be both “strong” and “highly representative of the trucking industry.” Approxi- mately 13% of responses were from owner–operators. ATRI researchers acknowledged in the report that online “con- venience” surveys may favor carriers with a technology- orientation or those that have strong perspectives on the speed limiter issue. Of the respondents from the privately owned carriers, 79% (of all respondents in that sector) used speed governors compared with 64% of the truckload sector, 54% from the less-than-truckload sector, and 58% from the specialized sec- tor. Overall, 63% of carriers reporting using speed governors. Those carriers that used speed governors accounted for 77% of the trucks represented by carriers who responded to the survey, a testament to the increased likelihood among larger carriers to use speed limiters. These utilization rates are com- parable to rates identified in the OOIDA study. The ATRI results also showed that large carriers are more likely to use lower speed settings than small carriers. Inter- estingly, whether carriers used speed limiters or not, they identified safety as the primary motivation for either adopt- ing or avoiding the technology. The primary reason for those carriers choosing not to utilize speed limiters was car–truck speed differential. Slightly more than 27% of the respondents reported that driver tampering with speed limiter settings was an issue. Nearly all carriers indicated that the consequence for tampering was immediate termination. McDonald and Brewster (2007) found it difficult to mean- ingfully compare fleet safety data before and after speed lim- iter installation owing to the low number of respondents (56 carriers) that provided objective safety data (in terms of vehicle miles traveled per million miles for pre- and post- limiter installation). Owing to the lack of data for these sur- vey items, it was not possible to make strong claims about safety outcomes for carriers after the implementation of speed governors. Carriers’ assessments of the optimal speed to maximize safety, fuel economy, and productivity indicated that optimal safety was achieved at a lower speed than optimal fuel efficiency, which itself was achieved at a lower speed than optimal productivity.

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Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses Get This Book
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TRB's Commercial Truck and Bus Safety Synthesis Program (CTBSSP) Synthesis 16: Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses explores issues associated with speed limiters including measurable safety impacts, metrics, and degree of benefit. Speed limiters, also described as speed governors, are devices that interact with a truck engine to only permit the attainment of a pre-programmed speed.

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