The legislative drive to allow the nationwide operation of twin 33-ft trailers isn’t the only effort under way on Capitol Hill to liberalize federal truck size/weight limits. The Coalition for Transportation Productivity is revving up its lobbying to increase the federal vehicle weight limit to 97,000 pounds for tractor-trailers equipped with a sixth axle.

CTP, a coalition of nearly 200 manufacturers, shippers, carriers and allied associations, says it "advocates for heavier-- not bigger-- six-axle trucks that meet the same safety standards as trucks currently allowed on interstates.”

To help make its case, this week the group urged Congress to review data from the Dept. of Transportation’s Comprehensive Truck Size & Weight Limits Study and then act to enable the heavier rigs.

The coalition sent a letter by CTP executive director John Runyan to members of Congress as well as a document highlighting data from the  DOT’s technical findings that CTP said demonstrate the safety of heavier, six-axle trucks-- as well as how they would reduce logistics costs, pavement life-cycle costs, fuel costs, vehicle miles traveled, congestion and emissions.

While the letter points to positive findings within the federal report, it also takes DOT to task for how it categorized the results of its study of size/weight limits.

“The actual study data provides strong support for allowing trucks equipped with six axles to carry more freight on Interstate System highways,” Runyan’s letter states. “This is the real message for Congress, despite the fact that U.S. DOT political leadership, after three years of study and 1,100 pages of released data, wrote a cover letter citing insufficient information and recommending against any changes in truck size and weight regulations. While the Administration could not find a political path to support truck weight reform, we urge members of Congress to review the study findings for themselves and allow carefully crafted reforms in vehicle weight regulation to move forward.”

In both its letter and accompanying document, CTP cites DOT technical findings that six-axle trucks “weighing either 91,000 or 97,000 pounds maintain key braking and handling characteristics, allowing them to safely ship more freight and reduce vehicle miles traveled, logistics and pavement costs, and environmental impacts.”

CTP also notes that while “DOT justified its call for inaction by referencing a higher crash rate for six-axle trucks operating over a limited time period in the state of Washington, the technical report also shows that none of those accidents involving six-axle trucks were fatal. In contrast, the study found that five-axle trucks weighing 80,000 pounds (the current federal gross vehicle weight limit) were involved in 10 fatal crashes in Washington State during the same period.”

According to CTP, it favors “carefully crafted truck weight reform giving each state the option to set higher Interstate weight limits only for trucks equipped with six axles rather than the typical five. Because one-quarter of U.S. truck shipments meet the current Interstate weight limit with space left in the trailer, this proposal would allow companies to meet demand with fewer vehicles and make the U.S. transportation network more efficient, especially as gross domestic product and population continue to grow.”