PORTLAND – A coalition of advocacy groups said Wednesday that raising truck weight limits on the interstate through northern Maine would make the highway more dangerous and serve as a steppingstone to higher weight limits in other states.

Efforts to allow trucks up to 100,000 pounds on federal highways in Maine are misguided and a threat to public safety and road infrastructure, said Joan Claybrook, president of Public Citizen, a consumer advocacy group in Washington.

“Maine is part of the truck industry’s strategy to lobby for bigger, heavier trucks in all states,” she said.

Her comments came during a telephone conference call that also included representatives for Advocates for Highway and Auto Safety, the New England chapter of the Public Interest Research Group, Parents Against Tired Truckers, the Coalition Against Bigger Trucks and other groups.

Under federal law, trucks weighing up to 100,000 pounds are allowed on the Maine Turnpike section of Interstate 95 from New Hampshire to Augusta, but are forbidden on other stretches of interstate, including I-95 from Augusta north. State law allows trucks up to 100,000 pounds on state roads.

The Maine Department of Transportation and the state’s congressional delegation are among the supporters of increasing the interstate weight limit.

They say the lower limit on the northern stretch of I-95 forces trucks off the interstate and onto secondary roads, diverting them through residential areas and business districts. The lower weight limit also puts Maine at a competitive business disadvantage, they contend.

A 2004 Department of Transportation study concluded that raising the weight limit would result in increased safety, according to Herb Thomson, spokesman for the DOT. It also would save money in bridge and pavement costs because many trucks would go from secondary roads to the interstate, which is built to better withstand the heavier weights, the study concluded.

“If you reduce the payload that a heavy truck can carry, that means there’s going to be more trucks on the road to carry the same amount of payload,” Thomson said. “Increasing the amount of trucks isn’t something we want to do either.”

The opposition groups said a higher weight limit doesn’t guarantee that trucks will be removed from secondary roads, but will ensure that the interstate will be more dangerous by giving “behemoth trucks” free rein of the highway.

It would take an act of Congress to increase the weight limits, but if that happens it’s a good bet the trucking industry will attempt to raise the weights in other states as well, said Jerry Donaldson, director of research for Advocates for Highway and Auto Safety.

As it now stands, trucks over 80,000 pounds are allowed on interstates in New Hampshire and parts of Maine, while a patchwork of exemptions allows them on various stretches of different highways in different states, he said.

At the moment, nothing is on the table in Congress to raise the weight limits. Previous efforts have been unsuccessful.

U.S. Sen. Olympia Snowe met with Transportation Secretary nominee Mary Peters on Wednesday to discuss transportation issues facing Maine, including Snowe’s desire to have the weight limits raised.

Snowe said an accident in May in which an elderly woman was killed on a Bangor street by a fuel truck underscores the need to get large trucks off secondary roads.

“It simply makes sense to move these trucks onto those roads that can best handle them, and those are our federal highways,” said Snowe.