It has been more than 25 years since the U.S. addressed the question of federal interstate highway truck weights. Tom Carpenter, director of logistics for North America with International Paper, believes it's time to revisit the issue. Since that time, he says, the country has seen technological advancement, economic growth, severe congestion on the roads and major challenges to logistics productivity. All of which adds up, in his opinion, to the need for higher weight limits on the interstate.

Bills pending in the Senate and House of Representatives seek an increase in the maximum gross weight of trucks from 80,000 to 97,000 pounds - but only on vehicles equipped with a sixth axle. Carpenter says the measures address the current "patchwork quilt" of rules and regulations on state highway limits, "that makes the U.S. very confusing from a weight-regulation standpoint."

Under the proposed law, states would have the opportunity to opt in to the higher limits. They would be able to sit down and review the issue with state department of transportation leaders. "Each would be able to make an informed decision," says Carpenter. He believes that once most states review the research, and realize the opportunity to increase truck productivity, they will adopt the new federal rules. "We think it would be a pretty easy decision," he adds.

A 2010 pilot program in Maine bore out the feasibility of the idea, according to Carpenter. It gave heavier trucks, which were already allowed on the state's highways, access to the interstate. The results, he says, were improved safety and increased fuel efficiency.

Even with a new law, Carpenter doesn't expect the shift to happen overnight. While some states would adopt it quickly, trucking companies would have to invest in vehicles with the additional axle. The trucks wouldn't be larger, he notes, only heavier - by 17,000 pounds at their maximum.

The number-one predictor of highway safety is total vehicle miles traveled, Carpenter says, adding that the use of heavier trucks would reduce that number, leading to a drop in fatal accidents. There were 14 fewer accidents in Maine during the state's pilot program, he notes. Moreover, he says, the additional axle maintains the braking performance of the five-axle truck, even with a significantly heavier load.

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