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Suggested Citation:"Chapter Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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 Three - Survey Results." 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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15 Based on the many issues raised in the literature review, and using the ATRI survey as a starting point, the Study Team developed a survey for fleet safety managers and trucking industry experts. The survey can best be described as a small population convenience survey of the CMV industry; as such, the results may not be representative. It is not known whether the survey responses are representative of the overall trucking and motor coach industry. The survey consisted of 27 multiple-choice questions and was designed to take about 10 min to complete. The initial questions gathered basic data such as fleet size and type of oper- ations. If a fleet did not use speed limiters, the respondent was asked to select one or more reasons for the lack of use and no further questions were asked. If a fleet used speed limiters, the respondent was asked about the effectiveness of speed limiters in terms of perceived fleet safety, driver acceptance, vehicle operations, and related issues. General comments and sugges- tions were also solicited. The respondents were assured that all information provided would be kept strictly confidential. Approximately 1,500 surveys were distributed by e-mail and 103 responses were received, resulting in a response rate of approximately 7%. The full survey is presented in Appendix B. DETAILED SURVEY RESULTS Following are the survey results for each survey question. The actual survey questions are noted in italics and the corre- sponding results are noted beneath each question. 1. Number of years you have been a safety manager ( for commercial vehicle operations): • Mean years experience at current company = 15 years (range 0.5–53 years). 2. Your approximate number of years experience in commercial vehicle operations. • Overall mean years experience in commercial vehi- cle operations = 26.8 years (range 4.5–55 years). 3. Number of power units in your company’s fleet: _______ power units. • Mean number of power units at current company = 1,124.8 (range = 5–30,000). There were a total of 99 responses to this question. The mean number of power units can be somewhat deceiving as the mean suggests the majority of our survey respondents managed large fleets. However, a few very large fleets skew these results. As shown in Table 1 and Figure 1, the majority of survey respondents reported fleet operations with 21 to 100 power units (33.3%), followed by 101 to 999 units (28.3%), 6 to 20 units (22.2%), more than 1,000 units (14.2%), and 1–5 units (2%). Thus, a median calculation shows that most respondents managed small- to medium-sized fleets. 4. How would you characterize your fleet’s primary oper- ation (select one)? • See Table 2 and Figure 2. Other fleet types included: • Government contractor • Government • State government • Local government 5. Does your organization use speed limiters in any of your trucks? • Percent who use speed limiters = 82.5% (n = 85/103). • Percent who do not use speed limiters = 17.5% (n = 18/103). If “NO,” then why (select all that apply): • See Table 3 and Figure 3. Comments provided by respondents for not using speed limiters were: • Our engine control module (ECM) data do not show we have a problem with drivers speeding. • All trucks governed; speed maintained by “Is my driving safe” and then drivers receive feedback on driving. • No cost—all you have to do is set maximum speed for cruise and road speed in the engine ECM. [This is seem- ingly a comment in support of speed limiters.] • We have excellent drivers who respect the laws; we run all 48 states and don’t see the need to limit our trucks. I believe a truck that is limited to a speed less than the posted speed limit produces a hazard to other vehicles using the highway at posted speed limits. • Keeping steady speed (use cruise as much as possible). • Driver frustration and traffic safety. • With our industry terrain (off road—in forests, etc., the land is hilly, sandy, extremely wet in some seasons, etc.) [speed limiters] will not work. Also, our forestry trucks must be able to resume or decrease to or from a high idle when the trucks are loading as they have loaders CHAPTER THREE SURVEY RESULTS

16 1–5 Units 6–20 Units 21–100 Units 101–999 Units >1,000 Units % 2.0% 22.2% 33.3% 28.3% 14.2% N 2 22 33 28 14 Out of 99 responses. TABLE 1 DISTRIBUTION OF FLEET SIZE (power units) FIGURE 1 Distribution of fleet size (power units). % N For Hire: Local Haul 27.4% 29 For Hire: Long Haul 48.1% 51 Private: Long Haul 6.6% 7 Private: Local Haul 16.0% 17 Passenger Carrier: Local Haul 0.0% 0 Passenger Carrier: Long Haul 4.7% 5 Other 3.8% 4 Note: Respondents could select more than one fleet type, thus percentages will sum to more than 100%. TABLE 2 FLEET PRIMARY OPERATION FIGURE 2 Fleet primary operation.

17 with their units and they require a lot of power for a proper operation. 6. Do you use a speed limiting device that was factory installed by the engine or vehicle manufacturer? • Percent usage of factory-installed speed limiter = 95.3% (n = 81/85). • Percent usage of non-factory-installed speed lim- iter = 1.2% (n = 1/85). • Percent of non-response to question = 3.5% (n = 3/85). 7. Please estimate what percentage of your fleet uses speed limiters: _____% • Percent of power units equipped with speed lim- iter = 90.1% (range = 7%–100%). 8. How many years have speed limiters been installed in your vehicles? • Mean years power units equipped with speed lim- iters = 11.5 years (range = 2–27 years). 9. Does your company set a cruise-control speed limit that is different from a non-cruise-control (on-pedal) speed limit? • Percent of respondents who have a separate cruise- control speed = 43.4% (36/83). • Percent of respondents who do not have a separate cruise-control speed = 56.6% (47/83). • Mean cruise-control speed setting = 65.6 mph (range = 55–75 mph). What is your cruise-control speed? _____ mph • See Table 4 and Figure 4. 10. What is your non-cruise-control (on-pedal) speed? • Mean non-cruise-control setting = 67.2 mph (range = 57–73 mph) (see Table 5 and Figure 5). 11. Do you require speed limiters for owner–operators you hire? • Percent of respondents who require owner–operators to use speed limiters = 14.5% (12/83). • Percent of respondents who do not require owner– operators to use speed limiters = 36.1% (30/83). • Percent of respondents who indicated this question was not applicable to their organization = 49.4% (41/83). 12. How did you determine the governor speed to set in your fleet (mark all that apply)? (See Table 6 and Figure 6.) Comments provided by respondents were: • Reduce maintenance cost. • Original Equipment Manufacturer value and Return of Investment. • Factory settings. • Maintenance, tire, time to overhaul cost increases. • Based on my own driving experience I felt that 10 kph per hour over the limit was realistic. • Ontario Trucking Association recommendation. • Economic reasons. % N Cost 33.3% 6 Delivery Time 5.6% 1 Car–Truck Speed Differentials 61.1% 11 Inability to Accelerate 38.9% 7 Owner– Operator Refusal 33.3% 6 Avoid Workplace Conflict 11.1% 2 All Vehicles Must Have Speed Limiters 11.1% 2 Drive Faster 11.1% 2 Note: Respondents could select more than one fleet type, thus percentages will sum to more than 100%. TABLE 3 REASON FOR NOT USING SPEED LIMITER FIGURE 3 Reason for not using speed limiter.

18 13. What are the TOP 3 intended goal (s) of speed limiters (please write number 1, 2, or 3 to rank order). (See Tables 7 and 8.) More specific comments provided by respondents were (with number of similar responses in parentheses): • Fatigue management aid (3). • Reduce driver fatigue (4). • Financial liability in crashes. • Reduce crash severity (3). • Send message of the importance of speed control (3). • Improve maintenance cost (3). • Vehicle wear (3). • Reduce maintenance, tire, and time to overhaul costs. • Managing our corporate image. Speeding trucks carry the wrong message to the public. I lobbied for a tighter speed control for years, and was only successful as fuel prices climbed (3). • Overall safety (3). • Insurance rates (2). • Liability issue if involved in a speed-related accident (1). 14. Do you have any variations in the top speed of the speed limiter among your drivers? For example, dif- ferent speeds for drivers with an excellent or poor safety record. • Percent of respondents who indicated variations in the top speed of the speed limiter = 11.9% (10/84). • Percent of respondents who did not indicate variations in the top speed of the speed limiter = 88.1% (74/84). Specific comments were: • If a driver receives two speeding violations, the speed limiter is reduced to 58. • Drivers with 2 Million Safe Miles are set at 65 mph. • Testing the speed on fuel mileage of new 08 engines. • Based on state law. • Any driver convicted of a speeding violation has speed reduced by 3 mph for 6 months. • All students who come to us are set at 65, veteran guys are at 70. If they are put on probation for any safety related reason they are set at 65. • Why would you take your safest driver and then provide him/her with a higher rate of speed? The goal is safe cost to operate. Giving a higher speed does NOT improve productivity. It only increases costs of operation that ultimately will reduce drivers pay. It has to come from somewhere. • If accidents occur, speed is reduced further for one year. • Limit top speed to 65 mph for drivers with safety viola- tions. • Some higher risk drivers have speed reduced to either 62 mph or 56 mph. 15. Have drivers tampered with the speed limiter settings? • Percent of respondents who indicated a driver tam- pered with speed limiter = 22.6% (19/84). • Percent of respondents who indicated no driver tampering with speed limiter = 77.4% (65/84). • Percent of respondents who indicated a driver tam- pering with speed limiter who have a policy (penal- ties) for tamperingwith speed limiter = 94.7% (18/19). >70 mph % 13.8% N 60–64 mph 30.6% 11 65–69 mph 50% 18 5 55–59 mph 5.6% 2 Out of 36 responses. TABLE 4 SPEED BINS FOR CRUISE CONTROL FIGURE 4 Speed bins for cruise control. >70 mph % 34.6% N 60–64 mph 12.8% 10 65–69 mph 48.7% 38 27 55–59 mph 3.8% 3 Out of 78 responses. TABLE 5 SPEED BINS FOR NON-CRUISE CONTROL

19 FIGURE 5 Speed bins for non-cruise control. Other % 9.4% N Safety 90.6% 77 Posted Speed Limit 56.5% 48 Fuel Mileage 69.4% 59 Insurance Requirement 16.5% 14 Driver Input 16.5% 14 Followed Other Trucking Organization 11.8% 10 8 Out of 85 respondents. Note: Respondents could select more than one choice, thus percentages will sum to more than 100%. TABLE 6 HOW SET SPEED FOR SPEED GOVERNOR WAS DETERMINED FIGURE 6 How set speed for speed governor was determined. Other Mean 2.55 N Reduce Top Speed 1.61 47 Reduce Overall Speeding 2.03 31 Reduce Crashes 1.73 49 Reduce Speed Violations 2.33 27 Reduce Tire Wear 2.41 17 Increase Fuel Economy 1.94 66 11 Out of 85 respondents. Note: Not all respondents chose three goals. TABLE 7 TOP THREE INTENDED GOALS OF SPEED LIMITERS (ranked as 1, 2, or 3)

Responses to tampering were listed as: • Discipline • Discipline including termination (2 responses) • Will be given warning for 1st violation and fired for 2nd violation • Termination (13 responses) • None to date, but should it occur it would be considered destruction of company property. 16. Based on your experience, how successful have the speed limiters been in reducing speeding violations? (See Table 9 and Figure 7.) 17. Based on your experience, are you aware of drivers traveling faster than normal in lower speed areas in order to “make up” time “lost” by using a speed lim- iter on interstate routes? • Percent of respondents who indicated that drivers do this behavior = 88% (n = 73/83). • Percent of respondents who indicated that drivers did not do this behavior = 12% (n = 10/83). Specific comments were: • Get as many miles as possible. • Our pick-up and delivery appointments are set based on appropriate transit times considering the governed speed and speed limits making it unnecessary for a driver to speed to make up time. If they feel the need to speed to make up time it’s because they have wasted time some- where else. • Although I don’t believe it is a widespread problem, I am not sure that they do it to make up time. I think it is mainly due to habit. 20 • Simply disobeying the posted speed limits. Nothing to do with making up time. • Tracking system also provides data on units exceeding speed limits. • Had one driver that complained max speed was 64 mph “he knew speedometer was correct because radar speed sign told him so while driving through 45 mph con- struction zone.” • Based on logged time and miles w/metered time/date stamps (mean speed is very high). • Regardless of speed limiters, the vehicle operator will often speed through lower speed areas if he or she believes they can get away with it. The excuse of “mak- ing up lost time” has long been tried and lost. Chronic speeders will take the opportunity to speed in any speed controlled area they believe they can get away with. 18. Based on your experience, how successful have the speed limiters been in reducing crashes? (See Table 10 and Figure 8.) 19. Based on your experience, how successful have the speed limiters been in reducing tire wear? (See Table 11 and Figure 9.) 20. Based on your experience, how successful have the speed limiters been in increasing fuel economy? (See Table 12 and Figure 10.) 21. Based on your experience, how often do the speed limiters reduce on-time delivery? (See Table 13 and Figure 11.) 22. Based on your experience, what has the driver response been toward the speed limiter? (See Table 14 and Figure 12.) Top Three Intended Goals for Using Speed Limiter Total Reduce Top Speed Reduce Crashes 49 Increase Fuel Economy 47 66 Reduce Overall Speeding 31 Reduce Speed Violations 27 Reduce Tire Wear 17 Other Mean Ranking 1.61 1.73 1.94 2.03 2.33 2.41 2.55 #1 27 22 24 5 0 2 9 #2 11 22 12 10 18 8 1 #3 9 9 10 20 14 8 7 11 Out of 85 respondents. TABLE 8 TOP THREE GOALS FOR SPEED LIMITERS, SHOWING RANKING PREFERENCES Cannot Determine % 7.1% N Very Successful 34.5% 29 Successful 29.8% 25 Neutral 23.8% 20 6 Very Unsuccessful 0.0% 0 Unsuccessful 4.8% 4 Out of 84 responses. TABLE 9 SUCCESS OF SPEED LIMITERS IN REDUCING SPEED VIOLATIONS

21 FIGURE 7 Success of speed limiters in reducing speed violations. Cannot Determine % 14.3% N Very Successful 17.9% 15 Successful 38.0% 32 Neutral 27.4% 23 12 Very Unsuccessful 0.0% 0 Unsuccessful 2.4% 2 Out of 84 responses. TABLE 10 SUCCESS OF SPEED LIMITERS IN REDUCING CRASHES FIGURE 8 Success of speed limiters in reducing crashes. Cannot Determine % 20% N Very Successful 14.1% 12 Successful 30.6% 26 Neutral 32.9% 28 17 Very Unsuccessful 0.0% 0 Unsuccessful 2.4% 2 Out of 85 responses. TABLE 11 SUCCESS OF SPEED LIMITERS IN REDUCING TIRE WEAR

22 FIGURE 9 Success of speed limiters in reducing tire wear. Cannot Determine % 3.6% N Very Successful 35.7% 30 Successful 40.4% 34 Neutral 17.9% 15 3 Very Unsuccessful 0.0% 0 Unsuccessful 2.4% 2 Out of 84 responses. TABLE 12 SUCCESS OF SPEED LIMITERS IN INCREASING FUEL ECONOMY FIGURE 10 Success of speed limiters in increasing fuel economy.

23 23. Based on your experience, in what way does having speed limiters on fleet vehicles impact driver hiring and retention? (See Table 15 and Figure 13.) 24. Have speed limiters negatively affected safety in any area of your operations? • Percent of respondents who indicated that overall speed limiters negatively affected safety = 3.6% (3/84). • Percent of respondents who indicated that overall speed limiters did not negatively affected safety = 96.4% (81/84). Specific comments from respondents indicating negative effects were: • Increased exposure to being rear-ended, mental stress on drivers as traffic runs around them, occasional road rage events with other motorists mad about our speed on clogged highways; these are all due to our set speed of 60 mph. We would have speed governors on our trucks regardless of the desired set speed we choose, they have wiped out open highway speeding problems for us where the posted speed is above our set speed. In the distant future I expect we will have speed governor settings tailored to the operation, long haul out west may be set to 65 or 70 mph while regional or short haul in more congested areas will remain at 60 mph for us. • Because we were the only one in our area to have speed limiters. 25. Have speed limiters negatively affected productivity in any area of your operations? • Percent of respondents who indicated that overall speed limiters negatively affected productivity = 3.6% (3/84). • Percent of respondents who indicated that overall, speed limiters did not negatively affected produc- tivity = 96.4% (81/84). Specific comments from respondents indicating negative effects were: • 65 mph is not top speed on interstate reducing long haul productivity. • Our fleet could cover more miles in a shorter time if our trucks were not governed or governed at a higher speed; however, we do not feel the trade-off of slight improve- ments in productivity offset the lower accident risk and cost improvements in fuel, maintenance, good will, etc. • Very slightly though, as drivers complain they can’t make appointments sometimes. 26. Overall, the use of speed governors has improved your fleet operations. (See Table 16 and Figure 14.) 27. Please feel free to write any comments, issues, or experiences you’ve had with speed limiters. • Speed limiters and on-board recorders have been part of our fleet strategy for more than 50 years. There is no doubt the combination of the two have helped us identify aggressive drivers and either improve their performance or get rid of them. We fully and totally support the recent initiative to add speed governors to all trucks in the United States; and that the principle should be applied to all vehicles on the road. % N Very Often 0% 0 Often 0% 0 Neutral 15.9% 13 Seldom 32.9% 27 Very Seldom 51.2% 42 Out of 82 responses. TABLE 13 DO SPEED LIMITERS REDUCE ON-TIME DELIVERY? FIGURE 11 Do speed limiters reduce on-time delivery?

24 FIGURE 12 Driver responses to the speed limiter. Cannot Determine % 8.6% N Strong Adverse Impact 0% 0 Adverse Impact 6.2% 5 Neutral Impact 77.8% 63 Positive Impact 4.9% 4 Strong Positive Impact 2.5% 2 7 Out of 81 responses. TABLE 15 AFFECT OF SPEED LIMITERS ON DRIVER HIRING/RETENTION FIGURE 13 Affect of speed limiters on driver hiring/retention. Cannot Determine % 2.4% N Very Positive 0% 0 Very Negative 1.2% 1 Neutral 64.6% 53 Positive 23.2% 19 Negative 8.5% 7 2 Out of 82 responses. TABLE 14 DRIVER RESPONSES TO THE SPEED LIMITER

25 • No issues with speed limiters except the rare driver that tries to bypass the limiter. There is no impact to our service or driver pay. • Would only install on current fleet if a federal requirement; if vehicle had it installed would keep it maintained and working. Consideration should be made for this to be a new vehicle requirement ver- sus having to install on older vehicles. • In the fleets we work with, some are very technology minded, and others (more vocational) are not. For the more progressive, if the device has a positive impact on productivity or efficiency, they might likely adopt such technologies. In fact, one such fleet that we are working with is looking to limit the oper- ating domain of the vehicle’s engine to ensure that it runs (on the average) more closely to its “sweet spot.” It also limits more aggressive drivers. The vocational fleets are really more interested in the bottom line. If there are no major benefits, they are not going to spend any funds on these devices. • Speed limiters have caused no issues in the charter operations we operate. I strongly believe this to be a good safety tool for all commercial vehicles. • We had on-board computers for years so the speed limiters only made the supervisor’s job easier by not having speeding violations to deal with after the fact. • In the Western states drivers will complain about the 70 mph limit; we adhere to our set speed limit. Secondary roads are where speed violations occur. • Speed limiters have been used very successfully in Europe for a very long time. Their experience should be invaluable to you. Another very good reason for legislating the use of speed limiters to vehicles that “haul stuff” is to allow them to NOT be subject to the most stringent CAFÉ standards. Fuel economy stan- dards should be different for vehicles that are to be used for the mobility of individuals than those for vehicles designed to move goods or large groups of people. Those vehicles necessarily need to be sub- stantially larger than personal vehicles and thus should not need to meet the same stringent fuel economy standards that should be met with personal vehicles. That said, those larger vehicles should also have their speeds restricted for the very reasons that you are studying. Thus, tying together fuel economy standards with speed limiters creates the proper mar- ket incentives. If one needs/wants a large vehicle to “haul stuff,” then that vehicle needs to be speed lim- ited. If instead one doesn’t need to “haul stuff” then one can purchase a fuel efficient vehicle that is not speed limited. My view is that way too many people are commuting in fuel inefficient macho trucks. Much of their macho would dissipate if they were speed limited. Also, for those that are really in the business of “hauling stuff,” they really don’t need nor desire to break the speed limit. • In my opinion, as an investigator of commercial vehicle accidents, I would speculate that most motor carriers utilize speed limiters (which I believe are standard equipment on all large commercial trucks and buses) to save fuel and keep the driver from driving at unreasonably high speeds. The speed limiters are difficult for the driver to tamper with, as they take special software and electronic equipment Strongly Disagree % 0% N Strongly Agree 28% 23 Agree 46.3% 38 Neutral 24.4% 20 Disagree 1.2% 1 0 Out of 82 responses. TABLE 16 OVERALL, HAS USE OF SPEED LIMITERS IMPROVED FLEET OPERATIONS? FIGURE 14 Overall, has the use of speed limiters improved fleet operations?

to change. One of the problems of speed limiters is the variation of speed limits in different parts of the country. In states where the maximum truck speed limit is 55 mph, perhaps 60 or 62 mph would be a reasonable setting. However, in the western United States where there are higher speed limits, 70 to 75 mph, and even 80 mph on stretches of I-10 in Texas, a lower setting would be frustrating to the driver and motor carrier. • The use of speed governors is widely used in the commercial vehicle industry in Europe. It makes no sense at all that we would take an 80,000 lb vehicle that will travel 80 mph off an assembly line and put it out on the highway. The debate should not be on whether speed governors should be used or not— the technology is available and we should use it. The debate should center on what is the correct gov- erned speed. I’m pretty sure we all would agree it’s not 100 mph. Is it 90 mph? Most would feel that is still too high, is it 80 mph? 70? 60? Our industry should be using the available technologies to improve highway safety and the reputation of the industry. Additionally, if the speeds were governed then the industry would essentially enforce posted speed limits on Interstates themselves allowing enforce- ment resources to be shifted to roadways with lower posted speed limits that tend to have higher instances of crashes. The net effect of governed maximum speed and a redeployment of enforce- ment to higher crash risk locations would be lower serious crashes. • When passing you can’t go any faster than the pre- set speed and tend to spend more time in the oncom- ing traffic lane. I like how some engine companies have a bonus speed program (i.e., 20 min in 8 h of extra speed to pass). When set at 100 kph (speed limit) most vehicles drive 108 kph and the trucks are always getting passed or create traffic congestion. • Cost of operating a commercial motor vehicle can be somewhat reduced when you hire, lease, and moni- tor driver performance prior to and during tenure with company. A bad driver (speed) will shift wrong and go against suggested driving manners. Bad habits cause some good things to sour. • As long as a truck can go the speed limit and have a little extra speed available to pass if needed speed limiters are not a problem. If the limiter is an attempt to make the truck go slower than traffic or the speed limit, then it will cause more accidents. I think very few accidents are caused by excessive speed of a truck. We are spending too much time and money going after trucks when we should be focusing on the cause of most accidents . . . cars. • Historically we used “governors” on engines; today, the ECM is easy to set to limit speed. • The problem that trucking companies still face is the unrealistic expectations of shippers and receivers. 26 Shippers/receivers do not care about FMCSA regu- lations (e.g., on hours of service, time allowed to driver, etc.). They want to be able to ship it late and have it delivered early. • When dealing in the area of passenger safety, you just cannot afford to have even one “loose cannon” amongst your driver force who may jeopardize the safety of his/her passengers by driving excessively fast. • The fleet has always used driver monitoring devices that included driver logs but most importantly tach- o-graphs that record movement, idling, and speed. As technology has advanced other technologies were introduced to ensure driver speed was being monitored. The highest legal speed limit for any units since 1940s was 65 mph. In 1973 speeds were dropped to 55 mph under federal rules. In 1981 due to driver input, speed limit was raised to 60 mph. At the same time the fleet added speed control devices that were basically a cruise control device that would also minimize maximum speeds to 60 mph. In 1994 with the Cummins M-11 engine we began shutting the trucks down through ECM parameters. We began setting the gear down protection at 49 mph to force them into top gear and at same time set maxi- mum cruise and road speed at 60 mph. Idle interrup- tion used to be set at 10 min in the early 1990s and in the late 90s it went to 8 min. Today, if a unit does not have the clutch depressed, is moving, or does not have a Power Take Off engaged, the idle time is 3 min. • Managing speed is the most cost-effective thing a fleet or any operator—even owner–operators—can do to reduce costs and improve bottom line (take home $$$$$$). If every truck on the highway operated at speeds no greater than 65 mph, cost of operations would reduce by as much as 30 cents— 15 cents per mile (i.e., cost of fuel when speeds are more than 55 mph, increased maintenance cost, increased tire cost, reduced time to overhaul). A good study that still holds true today is ATA’s (TMC) Technical Report, “55 vs. 65 An Equip- ment Operating Costs Comparison.” In the study, TMC illustrates that there is no productivity improve- ment between 55 mph and 65 mph. But there is a cost penalty of 1/2 mile per gallon in fuel + an almost equal cost in additional maintenance, tires, and reduced time to overhaul. At $3.00 per gallon a truck aver- aging 6 mpg at 60 mph will have a per mile fuel cost of $0.50. When increasing the speed to 65 mph (if re-geared to meet the engines sweet spot for fuel economy—$6,000) the cost per mile for fuel alone is now at $0.545 per mile with an additional equal cost (SWAG—Sure Wild Assed Guess) of $0.045 cent per mile in additional maintenance, tire, and reduced time to overhaul costs. The difference of 60 mph verses 65 mph is a conservative $0.10 (dime) per mile. You would have to run a lot of

27 miles to try and improve the productivity and you would have to haul an extra load to make up for additional cost—which in turn starts spiral over again—you never catch up. • Question 17 asked about speeding in lower speed areas to make up time lost by using speed limiters. While I do not feel that our drivers speed in lower speed areas to make up time, they do speed in those areas on occasion and would do so even if their trucks did not have speed limiters. Our drivers are paid by the hour and we constantly reinforce safety first even if it means being late, so there is less incen- tive for them to speed to “make up time,” whereas a driver paid by the mile has incentive to speed in order to make more money. If I am paid $0.40 cents a mile and I can travel 60 miles in an hour I will be making the equivalent of $24.00 an hour. If I travel 50 miles in an hour I am making $20.00 an hour, etc., at the end of the week that difference can add up. Of course the pressure from dispatch and the customer can drive the “need for speed” as well. • Most of our drivers are paid by the hour. Before set- ting the speed limit, we undertook a strong commu- nication program to carefully explain what we were doing, when, and why. Many drivers resisted, but they have come to accept it. Because they are paid by the hour, speed is more a “quality of life issue” than it is a perceived pay issue. For our drivers paid a per- centage of revenue, a maximum speed of 65 mph has caused us occasional recruiting issues, because limit- ing speed is perceived to reduce income (and it may). We’re OK with that. • I have not made any effort to track the “before and after” affects in terms of fuel economy or accident results, because I knew that regardless, I had no intention of raising the speed once we went through all the trouble of governing it. • I have always limited the speed on our company fleet. I have felt that our image was more likely to be posi- tive if the trucks were operating at a realistic speed. • When first installed we experienced a lot of negativ- ity, but after a very short time other issues like wages and benefits became more important to drivers. New drivers were informed of our speed limiter policy and there have been no issues with these employees. • It is without exception the only safe and economical way to run a trucking operation. • Our industry is capital intensive/low margin; thus, reducing operating costs is imperative to an organi- zations financial success. Controlling the largest controllable expense (i.e., fuel) is imperative. The bi- product is reduced tire and maintenance costs com- bined with reduced accident frequency and severity. Managing, planning, and executing our transactional activity in a safe and healthy manner should and must be our mandate for the employees and general public at large. • This is a safety initiative as well as fuel savings. . . . More importantly it is the right thing to do. • Success in trucking comes with reducing speed. Reduce accidents, save fuel, reduce maintenance costs. If government introduces a law to make it mandatory everyone wins. Driver complaints will subside when everyone is on a level playing field. Personally, I’m disgusted by speeding; trucks fol- lowing too close to other vehicles at 75 mph are out of control in an emergency. • Should not be controlled by government. Speed should be controlled by police and company owners. • Pulling heavy loads can be tricky at some points. Personally, I would not drive trucks myself any- more with that. Things are getting out of hand in the trucking industry. No more interest in trucking. • Based on Question 23, if a driver objects to speed limiting you do not want that driver. Also, if you have to make-up time then you are not properly dis- patching trucks—the biggest speed limit offenders are truckers that are on a pay per trip basis. Also, shippers that do not give enough advanced notice for deliveries. • The only detrimental effect of speed limiters is if the limiter is set on unrealistic limits and controlled by a government regulation or agency. Trucks should be allowed to go with the flow of traffic and not have a two-tier speed system to suit the conscience of a group of people that have no vested interest in transportation. • They are very good tools and should be used by all companies. • We always have to take into consideration the worst case scenario. We always want to strike a happy medium and we run Midwest and West. That is why we run more than 70 on top speed. • I’d be happy to see the national speed limit reduced to 55 mph again to reduce accidents and increase fuel economy. • Speed limiters only serve to ensure a maximum vehi- cle speed, thereby providing comfort in some assur- ance of public safety (as much as highway speed limitations will allow). Operators must recognize that company fleet drivers are prone to “pushing” the lim- its in the same fashion as the general driving popula- tion. So, the faster the unit can go, the faster the unit is likely to be driven! Speed limiters are not the answer to speeding violations other than in jurisdic- tions where the maximum posted speed cannot phys- ically be exceeded because of the limiter setting. Lower highway speeds will have some impact on vehicle maintenance costs in areas such as tire, brake, and engine wear resulting from lower speed and rpm. The fuel saving benefits are minimal for vehicles traveling more than 60 mph regardless of speed lim- itation beyond that number; however, there will be some savings for every 5 mph less of top speed

operation without limiter. It is better to have a minimal fuel saving than none at all! I believe the bottom line on this issue is, do not expect any signifi- cant economic advantage. Speed limiters will assist in a reduction in severity of highway crashes. In itself, the speed limiter will help to address the industry concern of public safety provided the limiter is not a “stand alone” carrier. This will address this fundamental industry responsibility. Speed lim- iters have a place in the current and future industry market. • Speed limiter had a made marginal effect on speed- ing and a great effect on cost control. Our owner operators do not have speed limiters and there is no difference in the number of accidents between com- pany trucks and owner operators. • I think they are great idea, but have to get all orga- nizations and transportation companies to go for it. • Do not agree with all trucks being governed at 105 kph. This will cause more problems on high- ways because trucks will be unable to pass, which will cause traffic jams. • We have used speed limiters in our trucks for years and would not operate without them. Having said that, we are not in favor of the proposed 105 kph mandatory speed regulations. We feel that 105 kph does not allow a driver to pass in an efficient and safe manner. Those carriers who are operating in the way that you are trying to target will move their base place of operations out of the province, making the law useless. Companies that want to operate in a responsible manner always will and those that do not will always find a way around it. SUMMARY OF RESULTS FROM THE WRITTEN SURVEY The following section is a summary of results obtained from 103 fleet safety manager respondents. Overall, respondents were experienced fleet safety managers, averaging 15 years experience in CMV safety. The fleets represented were fairly balanced across small through large fleets, but with few owner–operators. Operations concentrated on for-hire local and long haul, with emphasis on long haul operations. Five responses were received from passenger carriers. Use of Speed Limiters Eighty-two percent of respondents use speed limiters in at least some of their vehicles (averaging 90%). Of the 82% of respondents who indicated using speed limiters, 95% used factory-installed speed limiters and have done so for an aver- age of 11.5 years. A few respondents (14%) required speed limiters when owner–operators were hired, but for most (50%) the question was not relevant as they did not hire owner–operators. To assess respondents’ motivation for using speed limiters, they were asked to rank in order three choices 28 among six choices. The most frequent “number 1” response was “reduce top speed,” which also received the highest score with all responses weighted and aggregated. “Increase fuel economy” received the most votes (66) regardless of rank, followed by “reduce crashes” (47), and “reduce top speed” (49). The lowest score went to “reduce tire wear.” Comments from respondents indicated that fatigue management was noted 7 out of 11 times when “other” was marked. Perhaps this should have been one of the original choices. Other rea- sons for using speed limiters included reducing overall main- tenance costs, maintaining a positive corporate image, and reducing insurance rates. The 18 respondents who do not use speed limiters noted “car–truck speed differentials” as the primary concern (61%), with “inability to accelerate” when needed the second greatest concern (40%). When combined, “owner–operator refusal” and “avoid workplace conflict” represented 44% of the responses from the non-users. A few comments from respon- dents indicated their fleets did not have a problem with drivers speeding; therefore, there was no need for speed limiters. Speed Limit Setting Most respondents (90%) selected “safety” as the primary con- sideration for determining the set speed on their speed limiters, followed by “fuel mileage” (69%) and “posted speed limit” (56%). Respondents were evenly split in terms of setting a dif- ferent cruise-control speed limit from the on-pedal (non- cruise-control) speed limit. The majority (56%) of respondents did not use this practice. The difference in set speed between cruise-control and on-pedal (non-cruise-control) speed limiter was not noteworthy. The mean setting for cruise-control speed limit was 65.6 mph, whereas it was 67.2 mph for on-pedal operations (a difference of only 1.6 mph). About 12% of respondents operated with variations in top speed of the speed limiter based on driver performance. For drivers considered inexperienced or risky, speed settings are reduced. Comments from respondents included the following: • If a driver receives two speeding violations, the speed limiter is reduced to 58 mph. • Any driver convicted of a speeding violation has speed reduced by 3 mph for 6 months. • All students who come to us are set at 65 mph; veteran drivers are at 70 mph. If they are put on probation for any safety-related reason, they are set at 65 mph. One fleet allowed drivers with 2 Million Safe Miles to increase their set speed on the speed limiter to 65 mph. But one respondent commented, “Why would you take your safest driver and then provide him/her with a higher rate of speed? The goal is safe cost to operate. [Higher speed] only increases costs of operation that ultimately will reduce drivers’ pay. It has to come from somewhere.” Another respondent commented that the debate should move beyond “if” speed

29 limiters will be mandated and center around selection of the optimum governed speed. He also noted that governed speeds on heavy trucks “would essentially enforce posted speed limits on Interstates themselves, allowing enforcement resources to be shifted to roadways with lower posted speed limits that tend to have higher instances of crashes. The net effect of governed maximum speed and a redeployment of enforcement to higher crash risk locations would be lower serious crashes.” Tampering with Speed Limiters Tampering was cited by some respondents as a concern with speed limiters; however, only 22% of respondents reported such tampering. The typical fleet response was immediate termination, although some provided a warning on the first offense. Do Speed Limiters Cause Speeding? Anecdotal reports have indicated that speed limiters result in drivers driving faster in speed zones below the speed limiter set speed to “make up time.” Survey results supported this view, with 88% of survey respondents reporting this was most likely occurring. As one respondent noted, “Regardless of speed limiters, the vehicle operator will often speed through lower speed areas if he or she believes they can get away with it. The excuse of ‘making up lost time’ has long been tried and lost. Chronic speeders will take the opportu- nity to speed in any speed controlled area they believe they can get away with.” Overall Assessment of Positives and Negatives of Speed Limiter Use In terms of positive and negative attributes of using speed limiters, the results are as follows: • Reducing Crashes: 56% of respondents indicated speed limiters were either “successful” or “very successful” for this purpose. Only 2.4% (two respondents) reported they were “unsuccessful.” • Reducing Speeding Violations: 64% of respondents reported speed limiters were either “successful” or “very successful” for this purpose. Only 4.8% (four respondents) reported they were “unsuccessful.” • Reducing Tire Wear: 44% of respondents indicated speed limiters were either “successful” or “very success- ful” for this purpose. More than half (53%) reported they were either “neutral” or marked “cannot determine.” • Increasing Fuel Economy: 76% of respondents indicated speed limiters were either “successful” or “very success- ful” for this purpose. Only 2.4% (two respondents) reported they were “unsuccessful.” • Reducing On-Time Delivery: 84% of respondents indi- cated either “seldom” or “very seldom” for this issue, with the remainder “neutral.” No respondents reported that on- time delivery was undermined “often” or “very often.” • Driver Response: 64% of responses regarding driver response toward speed limiters were “neutral,” whereas 23% indicated drivers were “positive” and 9% were “negative” or “very negative.” • Driver Hiring/Retention: 77% of responses regarding the impact of speed limiters on driver hiring and reten- tion were neutral, whereas adverse and positive impacts were roughly equal at 6% and 7%, respectively. • Effect on Safety: 96% of respondents indicated speed limiters did not negatively affect safety, with 3.6% (three respondents) reporting that speed limiters had a negative effect on safety. Specific comments from respondents indicated that these negative influences were increased exposure to being rear-ended and men- tal stress on drivers as traffic flowed around them. • Effect on Productivity: 96% of respondents indicated speed limiters did not negatively affect productivity, with 3.6% (three respondents) reporting speed limiters had a negative effect on productivity. One specific com- ment indicated the negative effects on productivity were overshadowed by the positive effect on safety and fuel economy: “Our fleet could cover more miles in a shorter time if our trucks were not governed or gov- erned at a higher speed; however, we do not feel the trade-off of slight improvements in productivity offset the lower accident risk and cost improvements in fuel, maintenance, good will, etc.” The final question in the survey asked respondents about the “bottom line” use of speed limiters (i.e., have they improved fleet operations?). Sixty-four percent reported that, overall, speed limiters have improved fleet operations, whereas 24% of respondents chose a neutral stance. Only one respondent did not believe fleet operations were improved. Therefore, examining the results from the series of ques- tions on safety and other benefits of speed limiters, this group of respondents overwhelmingly (but not unanimously) reported noteworthy benefits with relatively few drawbacks. Clearly, respondents considered speed limiters an important part of their overall fleet management operations. Although the majority of respondents perceived the systems as reduc- ing crashes, no respondents indicated any quantitative data that would support their perceptions (if it did exist, it was not shared with the Study Team). However, as one respondent in the passenger transport sector reported, “. . . you just cannot afford to have even one ‘loose cannon’ amongst your driver force that may jeopardize the safety of his/her passengers by driving excessively fast.” It appears that cost control issues, such as fuel economy, were a predominate motivator, as reported by survey respon- dents. However, one comment on the safety effects of speed limiters was interesting: “Speed limiters have [had] a marginal effect on speeding and a great effect on cost control. Our

owner–operators do not have speed limiters and there is no difference in the number of accidents between company trucks and owner–operators.” Of the 39 general comments, improvements to overall operations, particularly fuel economy, was a major theme. With respect to safety, several spoke in terms of speed lim- iters as part of a larger safety management strategy, which includes on-board recorders, driver feedback, and perfor- mance improvement. Several comments pointed to the un- realistic expectations of shippers and receivers as the root cause of excessive speeding. As one respondent indicated, “if you have to make up time then you are not properly dis- patching trucks—the biggest speed limit offenders are truck- ers that are on a pay per trip basis.” In terms of driver response, one respondent whose drivers were paid by the hour called speed a “quality of life” issue for their workers. The respondent noted that, “before setting the speed limit, we undertook a strong communication program to carefully explain what we were doing, when, and why. Many drivers resisted, but they have come to accept it.” Alternatively, for other drivers paid a percentage of revenue, “a maximum speed of 65 mph has caused us occasional recruiting issues, because limiting speed is perceived to reduce income (and it may).” Another respondent described their process of implementing speed limiters as follows: “when first installed we experienced a lot of negativity, but after a very short time other issues like wages and benefits became more important to drivers. New drivers were informed of our speed limiter policy and there have been no issues with these employees.” Another summed his perspective up con- cisely by saying “if a driver objects to speed limiting you do not want that driver.” RESULTS FROM TELEPHONE INTERVIEWS In an effort to gather targeted information on specific topics related to speed limiter use among motor carrier populations, the Study Team conducted structured telephone interviews with 12 motor carriers. The specific speed limiter-related topics addressed in the telephone survey included the role of speed limiters in the carrier’s overall safety culture, driver reaction to governor use within the carrier’s fleet, and the collection of data designed to measure the safety effectiveness of speed limiters within the carrier’s fleet. Carriers were selected from a list of ATA’s Safety Policy Council members, Minnesota Motor Trucking Association Safety Council members, and Georgia Motor Trucking Safety Council members. Informally, an attempt was made to collect responses from carriers of varying sizes, geographic locations, and operational models. Of the 12 interviewed carriers, all used speed limiters within their fleet operations. All of the fleets required that speed limiters be used on all fleet vehicles. However, some carriers employed owner–operators who were not required to use speed limiters on the trucks they drove. 30 Role of Speed Limiters in Overall Carrier Safety Culture When queried about the ways that speed limiting devices have been integrated into their overall safety culture and operations, respondents expressed a wide range of view- points. At least one carrier indicated that it did not consider speed limiter use a part of their safety culture, but rather as a fuel saving measure. At the other extreme, one carrier reported that they believed speed limiters were at the heart of their safety program—because a driver cannot exhibit safe driving practices and speed simultaneously. Two survey responses were reported frequently by survey respondents. The first highlighted the “indirect” safety bene- fits of speed limiters. Five respondents indicated that speed limiter usage was critical to the overall safety of the fleet because limiters allowed drivers to expend mental energy on actual safe driving rather than monitoring speed. One respon- dent compared the effect of speed limiters with another safety system installed on the truck that does not allow the cruise control to engage while the truck’s lights are turned on. In daylight driving, expending mental energy to manage speed diverts the driver from other safety; although during night- time driving, requiring a driver to expend mental energy to monitor speed reduces the chance a driver will fall into a “lull” while driving. The second most frequent response noted the “direct” safety benefits of speed limiters. Four respondents reported that reduced speeds are likely to reduce crash severity. One respondent indicated that the operational model (heavy haul) of his fleet was being especially prone to vehicular crashes at high speeds. Respondents were asked to list the top five components of their safety program and rank the importance of speed lim- iters within these top five rankings. Three respondents ranked speed limiters “near the bottom” in terms of importance, although four respondents ranked speed limiters “very high” or “near the top of the list.” The remaining respondents were either unable to provide a ranking for the importance of speed limiters or explicitly ranked their importance “near the middle.” Driver Reaction to Speed Limiter Use Three respondents reported that drivers were unequivocally unhappy with being forced to use a speed limiter. According to one respondent, “They absolutely hate them. Their feel- ings toward them haven’t changed at all over time.” How- ever, one respondent reported that, “Drivers do not mind governors at all.” The majority of respondents reported that most drivers do not like speed limiters, but have accepted them and become more accustomed to their use as most car- riers require their use. Two respondents indicated that older drivers are generally more accepting of speed limiters and one respondent reported that training greatly reduced driver dissatisfaction with speed limiters.

31 Carrier Collection of Safety Data Relevant to Speed Governor Use All but one respondent indicated that they had not attempted to collect and analyze data to determine the effectiveness of speed limiters in improving safety within their operations. The respondent who reported objective evidence of safety improvements noted that the carrier had experienced issues with truck rollovers; however, these incidents were reduced because speed limiters and stability control systems were installed on their trucks. As has been found in previous studies, most carriers did not collect objective data related to speed lim- iter implementation within fleet operations. The lack of before and after data severely limits the ability of the Study Team to draw objective conclusions regarding the overall safety effec- tiveness of speed limiters. COMPARISON WITH AMERICAN TRANSPORTATION RESEARCH INSTITUTE AND OWNER–OPERATORS INDEPENDENT DRIVERS ASSOCIATION SURVEY RESULTS The OOIDA Foundation (2007) survey was much larger than the one conducted for the current synthesis. However, there was some overlap in content that allows meaningful compar- isons. Although the OOIDA results noted a strong driver pref- erence to drive without speed limiters, the responses in the cur- rent synthesis indicated that drivers will tolerate them—most fleet safety managers viewed driver response to speed limiters as a neutral factor in driver hiring and retention. Respondents in the OOIDA survey indicated their primary concern with speed limiters was the lack of passing speed followed by increased traffic congestion. Respondents in the current synthesis who reported not using speed limiters had similar concerns. Both surveys were consistent in finding a high incidence of drivers exceeding the speed limit in areas where the speed limit is less than the speed limiter setting. Although the OOIDA results indicated that this is done to make up for lost time, survey respondents in the current synthesis indi- cated that this was likely a matter of overall driver attitudes or habits. The OOIDA results showed a higher average setting for the speed limiter (69 mph) compared with the results from this synthesis (67 mph for non-cruise control and 65 mph for cruise control). The OOIDA respondents indicated that 9% of companies required owner–operators to speed limit their trucks, with 41% saying this is not a requirement. This tracks somewhat with the results from the current synthesis, with 14% affir- mative answers and 36% negative. The number of responses to the ATRI survey was twice that received in the current synthesis. The ATRI survey indi- cated the overall installation rates of speed limiters were 63% for motor carriers, whereas the results from this synthesis survey were much higher. The difference may be the result of the broader coverage of the overall industry that was accom- plished with the ATRI survey. Both surveys illustrate that safety is the primary motiva- tion for either adopting or avoiding speed limiters. As with the OOIDA study, those carriers choosing not to utilize speed limiters cited concerns with the car–truck speed differential created. The survey in this synthesis reported a 22% rate of driver tampering with speed limiter settings, which is roughly con- sistent with the 27% rate reported by ATRI. Both surveys found that, in most cases, the consequence for tampering was immediate termination.

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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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