A battle is brewing in Congress over allowing heavier and longer trucks on U.S. interstate highways, with some lawmakers from New Jersey and Pennsylvania on opposite sides of the debate.

As Congress inches toward a vote on a new transportation-funding law this year, both supporters and opponents of bigger trucks are lobbying to make their position part of the final bill.

The proposals for bigger trucks are supported by the American Trucking Associations and some industry and shipping groups, and they are opposed by the railroad industry, the American Automobile Association, and the Teamsters union.

Currently, federal law bans fully loaded trucks heavier than 80,000 pounds and longer than 53 feet from most interstate highways.

The American Trucking Associations is seeking to permit states to increase that maximum weight to 97,000 pounds. The proposal would require the heavier trucks to have six axles, up from the current five, to spread the weight over more wheels.

The industry also wants the federal government to allow states to permit longer trucks, with as many as three trailers hitched together. Such combinations are permitted in some Western states and on some turnpikes in the Midwest and East, but Congress in 1991 banned further expansion of such longer-combination vehicles as 76-foot "Rocky Mountain doubles," 96-foot "Turnpike doubles," and 84-foot "triples."

Opponents of the bigger trucks contend that the vehicles would endanger motorists, increase damage to roads and bridges, and increase costs to taxpayers for additional highway repairs.

Supporters say the bigger trucks would reduce the total number of trucks on the roads, making travel safer, and would shift heavy trucks to interstate highways from state and local highways, where the federal ban does not apply. They say the trucks would not increase highway damage because heavier loads would be dispersed over more wheels, and they say the trucks could be routed away from bridges unable to bear the heavier loads.

The supporters of the bigger trucks include Rep. Bill Shuster (R., Pa.), who is a cosponsor of a bill (HR763) introduced in February by Rep. Michael Michaud (D., Maine) to permit the heavier trucks.

On the other side, U.S. Sen. Frank Lautenberg (D., N.J.) this month introduced a bill (S876) to keep the current limits on truck weights and lengths on the 47,000-mile Interstate Highway System and to extend them to the 160,000-mile National Highway System, which includes state-funded U.S. highways. The cosponsors of a similar House bill (HR1574) include Reps. Robert Andrews (D., N.J.), Donald Payne (D., N.J.), and Tim Holden (D., Pa.).

Advocates on both sides insist their proposal would make highways safer.

"When you raise the weight limit or increase the size of the truck, you reduce the number of loads necessary to deliver the freight," said Darrin Roth, director of highway operations for the American Trucking Associations. "That reduces the number of miles traveled, which means fewer accidents, fewer emissions, and lower costs for freight."

Michaud, the prime sponsor of the House bill, said permitting bigger trucks on interstates would allow local industries to lower shipping costs and "it would promote safety . . . by making sure trucks aren't forced to take secondary roads through town centers in their travels up and down our state."

The Coalition Against Bigger Trucks, funded primarily by the railroad industry, cites studies by the U.S. Department of Transportation that found multiple-trailer trucks to be less safe to motorists and harder on highways and bridges.

"Multi-trailer combinations without compensating design features have inferior performance capabilities compared to single-trailer combinations and these differences, especially if frequently challenged in traffic-conflict situations, result in incrementally higher crash likelihoods," the Transportation Department found in a 2000 study.

AAA Mid-Atlantic, the motorists organization, opposes efforts to put heavier or longer trucks on interstates.

"Bigger trucks will mean bigger traffic problems and bigger risks," said Rick Remington, manager of public and government affairs at AAA Mid-Atlantic. "It's a simple matter of physics."

The Teamsters union, which represents truck drivers, also came out against bigger trucks. Union president Jim Hoffa said, "More than 600,000 of our 1.4 million members start their workday by turning a key in a vehicle. That gives Teamsters a real-life perspective on the dangers involved in increasing the size and weight of trucks."

Roth, of the trucking association, said opposition from railroads and truck drivers is driven by economics: Railroads would lose customers and truck drivers would lose jobs.

Both sides expect the debate to ultimately focus on deliberations in the House transportation committee, which is drafting a new, six-year transportation-funding bill. The chairman of the committee, Rep. John Mica (R., Fla.), has not taken a position on the big-truck issues, said aide Justin Harclerode.

Contact staff writer Paul Nussbaum at 215-854-4587 or pnussbaum@phillynews.com.