Several companies that ship their products by truck, including giants like Kraft Foods, Coca-Cola, MillerCoors and Campbell's Soups, have stepped up their efforts to get Congress to allow heavier rigs on the nation's interstate highways.

More than 100 companies and trade associations yesterday launched the Coalition for Transportation Productivity to support legislation raising the federal weight limit from the current 80,000 pounds to 97,000 pounds.

Proponents claim that allowing heavier trucks would mean fewer of them on the highways, thus reducing costs, congestion and pollution. They also say safety wouldn't be compromised because heavier trucks would be required to have a sixth axle, giving them more braking power.

"America's freight transportation infrastructure is on the verge of becoming overwhelmed over the next decade," said John Runyan, a senior manager of International Paper and co-chairman of the coalition.

"Freight hauled by trucks in the U.S. is expected to double by 2025, and truck traffic is growing 11 times faster than road capacity," he said. The coalition "is asking Congress to responsibly reform truck weight limits with proper safeguards to allow the same amount of freight to be carried on fewer trucks, which will improve the efficiency of our interstates, reduce fuel use and curb emissions."

The coalition said International Paper sent 600 trucks per week from an Alabama mill to Southeast markets last summer. With the higher limit, it would have used 450 trucks, cutting miles driven by 31 percent and fuel use and emissions by 18 percent.

The legislation has drawn criticism from highway safety groups and some in the trucking industry, including the Teamsters union and the Owner-Operator Independent Drivers Association.

"Throughout the past 50 years, trucking and shipping interests have relentlessly sought increases in truck sizes and weights," said a statement by the group Advocates for Highway and Auto Safety.

"These increases have been granted despite the clear threat to public safety and at the risk of increased bridge and pavement damage while imposing unfair, staggering costs on U.S. taxpayers for severe truck crashes and roadway damage.

"This time around, the trucking industry has taken a new 'green' approach that tries to make the U.S. public believe that big trucks can be safer, harm the environment less and use less fuel, if only Congress will enact legislation to make trucks even bigger and heavier than they already are. Nothing could be further from the truth."

A bill sponsored by Rep. Michael Michaud, D-Maine, would allow states to increase the weight limit to 97,000 pounds and impose higher fees to compensate for bridge damage from the heavier trucks.

Separate legislation co-sponsored by Pennsylvania's Reps. Mike Doyle, D-Forest Hills, and John Murtha, D-Johnstown, would freeze weight and size limits and extend them beyond the 40,000-mile interstate highway system to 161,000 miles of U.S. highways.

The issue may be resolved as part of Congress' consideration of a new highway funding authorization bill to replace the one that expires Sept. 30.