Click for next page ( 32

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 31
32 CHAPTER FOUR CONCLUSIONS CONCLUSIONS In the United States almost all large trucks (Class 68) man- ufactured in the last 5 to 7 years have the ability to govern speed Speed Limiters and Safety using the engine control module (ECM). However, the per- centage of fleets that use the ECM speed limiter functionality There is adequate literature on the role of large-truck speed in appears to be approximately 65% across the industry. At the terms of crash severity, but less empirical data relating to the sector level, there are more tangible differences, with larger use of speed limiters to meaningful reductions in total crashes fleets and private fleets being the primary users. because the percentage of crashes that occur above 65 mph is relatively small. However, the statistical impact could increase Finally, whereas some survey respondents indicated a over time, as indicated by Insurance Institute for Highway desire to receive insurance industry benefits, insurance com- Safety data showing that the number of trucks traveling over pany interview data conducted by American Transporta- the 75 mph speed limit rose from 8% to 14% during the period tion Research Institute (ATRI) and FMCSA show hesitancy from 1996 to 2006. by insurers to offer "front-end" premium discounts to carriers utilizing speed limiters. The general position of commercial Published studies indicate that both traveling above the insurers is that users of limiters will benefit "after the fact" posted speed limit and speed variance among vehicles increase from lower crashes and/or crash costs. Although this position crash exposure. Speed limiters, by restricting speed at or near presently differs from personal auto insurance, which credits the speed limit, also create such variances in speed relative to users of seat belts, anti-lock brakes, and other safety devices, other traffic. This is particularly prevalent in truckcar interac- there is some informal indication that greater amounts of tions where research shows that car speeds exceed posted speed empirical data on the use of limiters might positively influence limits at higher levels than do trucks. Although this situation commercial insurers. requires additional objective data, the Study Team found little in the way of published data that addresses the safety impacts Qualitative Analyses of speed limiters on commercial motor vehicles. Given the paucity of published objective results, the experi- The most definitive results on the effectiveness of speed ences of fleet safety managers and owneroperators are the limiters comes from the United Kingdom, which showed that best available sources of information. Two previous surveys the crash involvement rate for speed-limited heavy trucks plus a written survey conducted in the current synthesis shed fell 26% between 1993 (when mandated) and 2005. U.K. some light on the issues. Note that the current study had a low authorities noted that other contributing factors may have response rate (approximately 7%). The survey can best be influenced the decline, but concluded that speed limiters described as a small population convenience survey of the at least played a significant role. Although extensive objec- commercial motor vehicle (CMV) industry; as such, the results tive data exist regarding the use of intelligent speed adop- may not be representative and should be interpreted with this in tion speed limiters in European field trials, the differences mind. It is not known whether the survey responses are repre- between the application settings (arterials and residential sentative of the overall trucking and motor coach industry. streets versus highway), operational mode (personal versus commercial), and drivers (private citizens versus profession- In the ATRI study, researchers found it difficult to mean- als) are such that these results are not deemed relevant to ingfully compare fleet safety data before and after speed lim- this study. iter installation owing to the low number of respondents that provided objective safety data. However, qualitatively both the Speed Limiter Utilization ATRI and OwnerOperators Independent Drivers Association (OOIDA) surveys illustrate that safety is a primary motivation Mandated speed limiters are an established component of for either adopting or avoiding speed limiters. Those carriers safety policy in Europe and Australia. In Europe, the require- using speed limiters saw benefits in terms of both safety and ment for speed limiters has been extended to include not only fuel economy, whereas those choosing not to use speed limiters large trucks, but also medium-sized trucks. This is indicative cited concerns with cartruck speed differential. The OOIDA of European authorities' level of conviction that speed lim- study focused strongly on driver issues and in particular noted iters improve safety. that 81% of drivers reported that they would rather drive for a