The National Academies Press

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Pages 14-30

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From page 14... ... The initial questions gathered basic data such as fleet size and type of operations. 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. Read the entire page →
From page 15... ... FIGURE 1 Distribution of fleet size (power units) Read the entire page →
From page 16... ... 7. Please estimate what percentage of your fleet uses speed limiters: _____% • Percent of power units equipped with speed limiter = 90.1% (range = 7%–100%) Read the entire page →
From page 17... ... . • Percent of respondents who did not indicate variations in the top speed of the speed limiter = 88.1% (74/84) Read the entire page →
From page 18... ... 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. Read the entire page →
From page 19... ... (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. Read the entire page →
From page 20... ... 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. Read the entire page →
From page 21... ... TABLE 12 SUCCESS OF SPEED LIMITERS IN INCREASING FUEL ECONOMY FIGURE 10 Success of speed limiters in increasing fuel economy. Read the entire page →
From page 22... ... 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. Read the entire page →
From page 23... ... 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. Read the entire page →
From page 24... ... 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) Read the entire page →
From page 25... ... 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. Read the entire page →
From page 26... ... • 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 vehicle speed, thereby providing comfort in some assurance of public safety (as much as highway speed limitations will allow) Read the entire page →
From page 27... ... Perhaps this should have been one of the original choices. Other reasons for using speed limiters included reducing overall maintenance costs, maintaining a positive corporate image, and reducing insurance rates. Read the entire page →
From page 28... ... One specific comment 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 governed 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? Read the entire page →
From page 29... ... One respondent 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 nighttime driving, requiring a driver to expend mental energy to monitor speed reduces the chance a driver will fall into a "lull" while driving. Read the entire page →
From page 30... ... The ATRI survey indicated 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 accomplished with the ATRI survey. Read the entire page →

From page 14...

... The initial questions gathered basic data such as fleet size and type of operations. 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.