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Status Report, Vol. 42, No. 7 | June 15, 2007 Subscribe

Institute supports speed limiters as big rigs' interstate speeds rise

Speed limiters would be required in large trucks under a plan pushed by a big swath of the trucking industry to address the problem of deadly rig crashes.

The limiters, or governors as they're also known, would keep truck speeds to a maximum of 68 mph. Since about 1996 trucks with diesel engines have had speed-limiting capability built into their engine control modules, and many trucking companies use this to limit how fast their trucks can travel. Manufacturers often set maximum speeds at the factory per carrier specifications.

"Speed governors are a feasible and cost-effective way to maintain safer truck speeds," says Anne McCartt, Institute senior vice president for research. "Many fleets already voluntarily use them, and an Institute survey shows solid public support for adopting them."

The National Highway Traffic Safety Administration (NHTSA) and Federal Motor Carrier Safety Administration (FMCSA) solicited comments on opening rulemaking on speed governors at the urging of Road Safe America, individual motor carriers, and the American Trucking Associations.

Road Safe America plus 9 motor carriers petitioned FMCSA in September 2006 to require speed governors in all trucks made after 1990 with a gross weight exceeding 26,000 pounds. The group asked that trucks be limited to no faster than 68 mph.

An October 2006 petition to NHTSA and FMCSA seeks tamper-resistant governors in new trucks only. "This new requirement is necessary in order to reduce the number and severity of crashes involving large trucks," the American Trucking Associations said. The group also cited lower fuel and maintenance costs, reduced vehicle emissions, and longer tire life.

In 2005 about 5,000 people died in crashes involving large trucks. Eighty-three percent of these deaths were passenger vehicle occupants or others on the road, including pedestrians. People in smaller vehicles are vulnerable in crashes with large trucks, which can weigh 20-30 times as much as cars and require as much as twice the stopping distances. High speeds are an important crash factor, exacerbating the inherent mismatch between trucks and passenger vehicles. Speed limits for trucks vary. Six states and the District of Columbia set speed limits for trucks at 55 or 60 mph. Ten states have some roads with 75 mph speed limits for trucks.

Institute surveys indicate that truck speeds are increasing on rural interstates. In New Mexico, where the speed limit for trucks is 75 mph, the proportion of large trucks exceeding 70 mph increased from 27 percent in 1996 to about 43 percent in 2006. The percentage exceeding 75 mph more than doubled, rising from 4 percent to 10 percent. Truck speeds also increased substantially in Nevada, which has 75 mph speed limits on rural interstates. The proportion of trucks traveling faster than 70 mph increased from 29 percent in 1996 to 41 percent in 2006. During the same decade, the proportion of trucks topping 75 mph jumped from 8 to 14 percent.

"Clearly something needs to be done beyond traditional enforcement approaches to bring down truck speeds," McCartt says. "Speed limiters are a sure-fire way to address the problem."

The European Union, Australia, and Japan all require speed limiters in large trucks, McCartt adds. "Europe's experience with limiters that cap truck speeds at 56 mph demonstrates that a maximum truck speed well below 68 mph is practical. Setting speed limiters even lower would be safer, but 68 is a reasonable starting point for U.S. rulemaking," she says.

One trucking and logistics company using speed limiters is Dupre Transport LLC. The Lafayette, Louisiana, company limits the speed of its trucks to 65 mph.

"We believe limiting the maximum speed trucks can travel will limit the severity and the frequency of top-end speed accidents," chief executive Reggie Dupre said in comments to NHTSA. Using speed governors also helps to boost fleet fuel efficiency, Dupre adds.

J.B. Hunt, a Lowell, Arkansas-based carrier that cosigned Road Safe America's petition, agrees. "There is not a good reason not to take advantage of the technologies currently available on Class 7 and 8 [commercial motor vehicles] that will ensure that they do not operate on public roadways at speeds in excess of an established maximum speed."

A 2007 Institute survey of drivers nationwide indicates that 64 percent favor a speed governor requirement for large trucks. More than three-quarters of respondents who favor speed governors support a maximum speed below 70 mph. More than 8 of 10 drivers said speeding on interstate highways and freeways is a safety problem, and 4 of 10 drivers said it is a big safety problem.

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