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4 Traffic safety research literature (e.g., Accident Analysis as safety-conscious fleet safety managers from many CMV & Prevention) transport operations types [e.g., truckload, less-than-truckload Industrial safety management literature (Journal of (LTL), and private]. Additional safety managers were identi- Safety Research, Journal of Organizational Behavior fied based on collected information and through industry con- Management, Professional Safety, Occupational Health tacts (i.e., trade associations and carrier contact lists provided & Safety) by ATRI). To enhance the survey process, the respondents Proceedings of the American Society of Safety Engi- were offered a free copy of the project final report. This was neers seen as critical to obtaining an adequate respondent sample and Proceedings of the Transportation Research Board also served the primary aim of the CTBSSP--to disseminate Transportation Research Information System relevant findings and products and promote program visibil- Trade publications ity within the CMV industry. Web pages relating to CMV transportation safety. In addition to these searches of academic literature and ORGANIZATION OF THE REPORT other publications, the synthesis team contacted government agencies (both foreign and domestic), as well as trade asso- Chapter one provides a brief overview of the project, includ- ciations, state motor carrier organizations, and academic ing the problem statement, scope, objectives, and approach. resources, seeking information on unpublished speed limiter The chapter also discusses a primary survey that targeted studies. Specifically, they were queried as to past and current fleet safety managers to obtain additional insight as to usage applications, programs, and studies involving the use of speed levels and perceived benefits and drawbacks of speed lim- limiters; further, these contacts were asked to provide guid- iters from actual users. ance on any other speed limiter safety effectiveness studies. See Appendix A for the full list of organizations contacted. Chapter two describes the findings of the literature review, including the assessment of prior published studies regarding speed limiter use, effectiveness, and legislation. Although sev- Commercial Vehicle Industry Survey eral key findings are identified, the literature search revealed a paucity of relevant published research on how speed limiters A survey targeting fleet safety managers was developed based directly affect safety and driving behavior. The most definitive on issues identified in the literature review with the core results on the effectiveness of speed limiters comes from the objective of gaining additional insight as to usage levels and United Kingdom, which showed that the crash involvement perceived benefits and drawbacks of speed limiters from actual users. Several outside safety experts were included in rate for speed-limited heavy trucks fell 26% between 1993 the survey to gain additional perspective. The written survey (when mandated) and 2005. U.K. authorities noted that other was distributed by e-mail to approximately 1,500 individuals contributing factors may have influenced the decline, but con- (including multiple safety managers within specific compa- cluded that speed limiters at least played a significant role. nies), representing roughly 400 truck and motor coach fleets The chapter also proffers the advantages and disadvantages plus other industry stakeholders. of speed limiters as described in the literature. Positive impacts primarily focus on safety and fuel efficiency. Concerns raised As will be discussed in chapter three, the written survey in the literature against using speed limiters include a lack addressed topics such as fleet size, type of fleet operation, use of a consistent set speed across North America and the inabil- of speed limiters (number of vehicles, how long, etc.), opera- ity of a speed-limited vehicle to accelerate in risky traffic tional aspects (set top speeds, driver violations or tampering), scenarios. fleet assessment of safety benefit, operational impacts (speed- ing citations, fuel savings, slower/fewer deliveries, etc.), Chapter two also reviews the current utilization of limiters driver response, and overall experience with speed limiters. from multiple-user and non-user perspectives. Industry per- spectives on using speed limiters were illuminated by two The written survey was designed to collect core information surveys found in the literature. An OOIDA Foundation and provide guidance on follow-up telephone interviews with (OwnerOperators Independent Drivers Association) survey a small number of select fleet safety personnel with detailed reported that more than 81% of respondents would rather knowledge of speed limiters. The written survey results were drive for a company without speed limiters; with the drivers' analyzed to identify core speed limiter issues, which were the primary concern with speed limiters being the lack of passing focus of the telephone surveys. speed. An ATRI survey found overall installation rates of speed limiters at 63% for motor carriers, which are compa- For surveying fleet safety managers, the synthesis team fol- rable to rates identified in the OOIDA study. ATRI found it lowed the successful model used in prior CTBSSP studies by difficult to meaningfully compare fleet safety data before and members of the synthesis team. The initial contacts included after speed limiter installation owing to the small number of past CTBSSP survey respondents, who may be characterized carriers that provided empirical safety data.

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5 Chapter three presents the results of the Study Team's responses are representative of the overall trucking and motor primary survey and interviews with key safety managers. The coach industry. survey addressed topics such as fleet size, type of fleet opera- tion, use of speed limiters, operational aspects (set top speeds, Chapter four draws conclusions from the results, identi- driver violations or tampering), fleet assessment of safety fies gaps in our current knowledge, and offers potential steps benefit, operational impacts (speeding citations, fuel savings, for future research initiatives. The current synthesis pro- slower or fewer deliveries, etc.), driver response, and over- vides a preliminary understanding of speed limiter use in all experience with speed limiters. Note the response rate of CMV operations; it does not provide, however, a method- the current survey was approximately 7% (103 of 1,500 fleet ological comparison of before and after results applied uni- safety managers completed the survey). The survey can best formly across predefined truck and bus fleet operations. This be described as a small population convenience survey of final chapter outlines an approach to an in-depth empirical the commercial motor vehicle industry; as such, the results study that would harvest data from the commercial truck and should not be considered definitive and should be inter- bus industry with regard to the safety effectiveness of speed preted with this in mind. It is not known whether the survey limiters.