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33 company without speed limiters. In the survey conducted for iters, this group of respondents overwhelmingly reported note- this synthesis, labor concerns were also cited by non-users as worthy benefits with relatively few drawbacks. Clearly, speed a strong reason for not using speed limiters. limiter user respondents considered speed limiters an impor- tant part of their overall fleet management operations. Al- In the written survey, a large majority of respondents used though the majority of respondents perceived the systems as speed limiters in at least some of their vehicles. Their pri- reducing crashes, no respondents indicated any quantitative mary motivation for using speed limiters was noted as reduc- data that would support their perceptions. However, ATRI's ing the top speed of the vehicle to improve both safety and industry crash data shows that crash severity is highest among fuel economy. In addition to reducing vehicular crashes, sev- large truck crashes where speeds exceeded 45 mph. eral respondents also indicated that they viewed speed lim- iters as a fatigue management tool. In summary, these results provide strong anecdotal evi- dence that speed limiters were beneficial to fleet operations; The surveys indicated that speed limit settings on the however, the results suggest cost reductions associated with speed limiters were within a fairly narrow range of about fleet operations and high-severity crashes were greater than 4 mph (65 mph to 69 mph). Safety was selected as the pri- for a reduction in the frequency of large truck crashes. mary consideration for determining the set speed, followed by fuel mileage. Tampering has been cited by some as a con- cern with speed limiters. Depending on the survey, 22%27% POTENTIAL STEPS FOR AN EMPIRICAL STUDY of respondents reported such tampering. OF SPEED LIMITER USE The written survey documented anecdotal evidence of large Although this synthesis provides a general understanding of percentages of truck drivers (with speed-governed trucks) speed limiter use in CMV operations, as well as of generalized exceeding posted speed limits in zones posted below the speed impacts, it does not provide a methodological comparison of limiter set speed to "make up time." Survey results strongly before and after results applied uniformly across predefined supported the existence of this phenomenon, although respon- truck and bus fleet operations. An in-depth, empirical study dents disagreed on whether the effect resulted from speed lim- is needed to collect objective and subjective data in the com- iters or overall driving habits. Without additional research that mercial truck and bus industry with regard to the safety effec- cross references speeding with speed limiter/non-speed limiter tiveness of speed limiters. Such a project might consist of the use, it is difficult to determine the relationship. If the former following steps. effect is valid, application of intelligent speed adoption-type methods could be effective; that is, speed limiters that dynam- Detailed Survey of Implementation Programs ically adjust to changing speed limits as the vehicle traverses A detailed survey of the commercial truck and bus industries, its route. working with industry associations and manufacturers of Overall, a positive picture emerges from speed limiter speed limiter devices, to discover and classify technologies users who participated in the written survey. Fifty-six percent and techniques used in past application of speed limitation in of respondents indicated speed limiters were either "success- commercial trucks and buses. In addition, more detailed ful" or "very successful" in reducing crashes, and 64% information is needed on the active use of (versus simply the reported speed limiters were either "successful" or "very suc- existence of) speed limiters by fleet sector, size, driver expe- cessful" in reducing speeding violations. In operational terms, rience, carrier policies and enforcement, and other key vari- speed limiter users believed that limiters were either "suc- ables. These data can then be used to extrapolate benefits to cessful" or "very successful" in reducing tire wear (44%) and the larger fleet and CMV driver populations once additional increasing fuel economy (76%), whereas 84% indicated that empirical research data are obtained. "seldom" or "very seldom" did on-time delivery get reduced. Selection of In-Depth Survey Population Fleet safety managers indicated that driver attitudes toward speed limiters were largely neutral (64%), whereas 23% were Development of a detailed survey population, based on a strat- positive. Recognizing the seriousness of the ongoing driver ification of fleet size classes (e.g., large, medium, and small), shortage, it is also noteworthy that 77% viewed the impact of operational types (long haul, short haul, less-than-truckload, speed limiters on driver hiring and retention as neutral. private, and for hire), or by commodity types, driver categories, and overall safety performance classifications. Qualitatively, 96% of respondents indicated speed lim- iters did not negatively affect safety or productivity. When Development of Evaluation Schema asked whether fleet operations "overall" have been improved by speed limiters, 64% were positive, whereas 24% chose a Development of a set of quantitative and qualitative evalua- neutral stance. tion criteria and factors for analysis, including both safety per- formance and economic factors as a minimum, to serve as a Thus, synthesizing and examining the results from the basis for before and after comparisons, so that results of speed series of questions on safety and other benefits of speed lim- limiter technology application can be determined. Formal

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34 partnerships with industry would be useful to ensure that sen- tudinal and perception surveys. If feasible, identification of sitive internal safety data can be collected and analyzed. promising targets for fleets that have not yet implemented speed limiter application, but are willing to work in a pre- Development of Survey Analysis Schema application and post-application evaluation of results in a one-year time frame, would be ideal. Development of an attitudinal and perception survey for use with the population of drivers and fleets, which would then Development of Best Practices Recommendations be evaluated in the expanded study effort, would be useful. Content could include views on program success, perspectives One outcome could be the development of a set of best prac- on safety benefits and economic impacts, and evolution of atti- tices for implementing a speed reduction program, to include tudes of management and drivers over implementation period. detailing key factors that could lead to success of such a pro- These qualitative data could be compared and corroborated gram. This effort could also identify the relationships of with industry/fleet data as a validation tool. speed limiters to an overall fleet safety management culture and best practice use and commitments. Selection of Populations of Survey and Control Fleets Consultation with Insurers of Truck and Bus Fleets A selection of appropriate fleets would be an important part of the evaluation. Possible categories could be (1) fleets that As an additional component to this investigation, selected have implemented speed limiters in the past 5 years, (2) fleets insurers of truck and bus fleets could be involved to (1) develop that are planning implementation, and (3) control fleets. an understanding of insurance company views of speed limiter use and implementation and how this technology, with ade- Conduct Analysis of Survey and Control Fleets quate empirical data, may influence a priori risk evaluation and loss-pick ratings, and (2) develop and design aggregated An essential step would be to conduct analyses of the survey data sets relating to safety efficacy results of speed limiter and control fleets, including evaluation of impacts, and atti- technologies.