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13 More effective enforcement of existing speed laws; and noted "the positive effect of speed limiter devices on road Changing the circumstances that induce drivers to safety and the environment" but did not elaborate further on speed, namely shipper and receiver scheduling de- this point. Authorities in the United Kingdom stated that mands and compensation based on the miles driven or although some problems exist with tampering of the speed loads hauled. limitation device and thus more enforcement is needed, the overall results of the use of speed limitation devices are posi- OOIDA asserts the petitioners' real motivation is to reduce tive, especially in lowering the average speed of buses and competition for the limited pool of qualified drivers. OOIDA their accident and casualty rates. notes that many fleets that are members of the ATA use speed limiters and are seeking to remove driver concerns about speed Unfortunately, although the Netherlands field test earlier limiters as an issue in the hiring process (i.e., if everyone has assessed the effects of speed limiters on truck fuel consump- to have it, the ATA fleets will better be able to compete). tion, maintenance costs, damage costs, and speeding tickets, safety was not addressed (Vermeulen and Klimbie 2002). ASSESSMENTS OF SPEED LIMITER EFFECTIVENESS Regarding passenger cars, Varhelyi and Makinen (2001) conducted field trials in the Netherlands, Spain, and Sweden Safety Effectiveness of Speed Limiters: with an instrumented car equipped with a speed limiting device. Published Results Different speed categories, ranging from 30 to 120 kph, were This section discusses the effectiveness of speed limiters on tested across the three countries. The speed limiter reduced driver behavior. Unfortunately, there is a paucity of relevant driving speeds on roads with speed limits ranging from 30 to published research on how speed limiters affect driving behav- 70 kph; however, there were no significant changes on roads ior, particularly in terms of safety. As discussed in Appendix A, where the speed limit was above 70 kph. The authors concluded the search for published studies in this area was extensive, that heavy congestion and the prevailing speed below the including searches of journal articles as well as direct contacts posted speed limit contributed to the lack of significant results with government agencies in Europe and Australia. The studies on roads where the speed limit was greater than 70 kph. Speed identified that assessed truck driver behavior while driving a variances decreased significantly and approach speeds at truck equipped with a speed limiter are not of sufficient detail roundabouts, intersections, and curves were slower with the to be helpful in this analysis of safety effectiveness. Other speed limiter. Time gaps increased in the speed interval of 30 to studies focusing on the passenger car population are somewhat 50 kph, suggesting safer car following behavior. These results relevant and are reviewed here. suggest that the speed limiter had beneficial effects on driving behavior other than limiting the driver from exceeding the The European Commission (Report from the Commis- posted speed limit. sion . . . 2001) report cites studies (not further referenced in the report) that have been made on the effects of the use of Toledo et al. (2007) used a simulation-based evaluation of speed limitation devices on heavy commercial vehicles in the impact of speed limiters on traffic flow and safety. In their comparison with vehicles not fitted with them, as follows: model they estimated that 10% of the vehicles were equipped with speed limiters. They rationalized that this assumption The studies differ slightly in their conclusions but the following corresponded to a policy mandating speed limiters in all overall positive effects are noted: lower fuel consumption (from CMVs. The impact of two pre-set speed limits, 100 kph and 3% to 11%), lower maintenance costs (tyres, brakes, engine), 120 kph, at various speed distributions and congestion levels increased road safety (fewer casualties), more relaxed driving and lower insurance premiums as a consequence of less acci- was evaluated. The simulation showed that speed limiters dents. As negative effects the following are noted: decreased may reduce average traffic speeds by as much as 10% and the road safety when performing an overtaking manoeuvre as over- variability of traffic speed may also be significantly reduced. 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 Effectiveness of Speed Limiters: Industry Surveys 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 Given the lack of controlled studies, information as to speed positive for drivers, for companies, for society and for the envi- limiter effectiveness must be gleaned from the experiences of ronment. The negative aspects are small and avoidable: if all the speed limitation devices were set accurately to the same speed, CMV fleet managers and drivers. The results of recent sur- there would be less need for overtaking, and as the use of speed veys performed by OOIDA and ATRI are reviewed here. 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). OOIDA Foundation Survey The Commission report (p. 6) also included statements offered OOIDA supports its opposition of legislation to mandate by some member states regarding the road safety effectiveness speed limiters with the results of a survey conducted by the of speed limiters on commercial vehicles. Danish authorities OOIDA Foundation (Speed Limiter Survey Results Final
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14 Report 2007). The survey was sent to 15,382 OOIDA mem- 240 respondents provided demographic details along with bers who were listed in its database as hired drivers. There information on speed limiter installation rates, rationale for were a total of 3,422 completed surveys returned, representing use, speed settings, and the impact of speed limiters on per- a 22.3% return rate. sonnel. ATRI considers the responses to be both "strong" and "highly representative of the trucking industry." Approxi- The respondents drive for 2,080 different trucking compa- mately 13% of responses were from owneroperators. ATRI nies, of which 60.8% of these companies already had speed researchers acknowledged in the report that online "con- limiters installed. The survey asked drivers whether, if all venience" surveys may favor carriers with a technology- things were equal, they would rather drive for a company that orientation or those that have strong perspectives on the speed does have speed limiters or one that does not. As many large limiter issue. carriers already have speed limiters installed in their vehicle fleets and often have better pay and benefits, it is often seen as Of the respondents from the privately owned carriers, a tradeoff, so the question addressed driver preference of 79% (of all respondents in that sector) used speed governors driving with a speed limiter. Of 3,400 drivers, 2,780 (81.7%) compared with 64% of the truckload sector, 54% from the reported that they would rather drive for a company without less-than-truckload sector, and 58% from the specialized sec- speed limiters, 120 (3.5%) would choose a company with tor. Overall, 63% of carriers reporting using speed governors. speed limiters, and 500 (14.7%) said the issue was not a factor. Those carriers that used speed governors accounted for 77% of the trucks represented by carriers who responded to the The drivers' primary concern with speed limiters was the survey, a testament to the increased likelihood among larger lack of passing speed followed by increased congestion. carriers to use speed limiters. These utilization rates are com- Further, 80.8% of the respondents admitted they "some- parable to rates identified in the OOIDA study. times" exceeded the speed limit on roads or in areas where the speed limit is less than the speed limiter setting to make The ATRI results also showed that large carriers are more up for lost time. likely to use lower speed settings than small carriers. Inter- estingly, whether carriers used speed limiters or not, they Generally speaking, the approach and response rate of the identified safety as the primary motivation for either adopt- OOIDA study stands up well in comparison to similar studies. ing or avoiding the technology. The primary reason for those The response rate was very high for a mail survey. The study carriers choosing not to utilize speed limiters was cartruck was useful in that it was addressed specifically to the 15,000 speed differential. Slightly more than 27% of the respondents company drivers who are OOIDA members, excluding their reported that driver tampering with speed limiter settings was remaining 141,000 members who are owneroperators. The an issue. Nearly all carriers indicated that the consequence for CTBSSP Study Team did identify one area of concern: tampering was immediate termination. although the survey asked if the truck was equipped with a speed limiter (which most Class 8 trucks are), only 1,226 McDonald and Brewster (2007) found it difficult to mean- respondents answered the question regarding the top speed ingfully compare fleet safety data before and after speed lim- setting of the speed limiter, whereas 2,211 respondents indi- iter installation owing to the low number of respondents cated that their truck was equipped with a speed limiter. (56 carriers) that provided objective safety data (in terms of Because it is possible that the speed limiter is not active on vehicle miles traveled per million miles for pre- and post- an equipped truck, it remains unclear how many respondents limiter installation). Owing to the lack of data for these sur- were actually using the speed limiter. vey items, it was not possible to make strong claims about safety outcomes for carriers after the implementation of ATRI Survey Results speed governors. Carriers' assessments of the optimal speed to maximize safety, fuel economy, and productivity indicated In early 2007, ATRI conducted a web-based survey of motor that optimal safety was achieved at a lower speed than optimal carriers designed to collect information about speed limiter fuel efficiency, which itself was achieved at a lower speed than usage in large trucks (McDonald and Brewster 2007). The optimal productivity.