Last-minute political maneuvering by New Hampshire’s senior senator last year allowed that state to increase the weight limit on its interstate highways, leaving Maine as the only state in the Northeast with an 80,000-pound weight limit. As they have for years, Maine’s congressional delegation has teamed up to raise the limit, getting big, heavy trucks off the state’s winding back roads.

Their sensible suggestion is a three-year pilot program. If there are fewer crashes, the higher weight limit would remain in place. If not, the 80,000-pound limit would be back in force. This approach should finally put to the test the idea that raising the weight limit is unsafe while it allows Maine to be competitive with neighboring states and Canadian provinces that have higher weight limits.

It seems intuitive that large trucks should travel on the interstate, which is straighter, wider and usually less congested than Maine’s secondary roads. However, federal law now prohibits trucks weighing more than 80,000 pounds from most of the state’s interstate highways. An exemption granted in 1998 allows trucks weighing up to 100,000 pounds to travel on the Maine Turnpike and trucks carrying jet fuel are allowed to use the highway to get to Bangor International Airport to supply military planes.

It is past time to extend that exemption to the rest of Maine’s interstate system.

Data already collected show that the 80,000-pound limit has made Maine’s secondary roads, where the trucks are forced to go, more dangerous. The most recent study, conducted by Wilbur Smith Associates, an international infrastructure consulting firm with an office in Portland, found that the accident rate, per hundred million vehicle miles traveled, was more than four times higher on two-lane roads than on the Maine Turnpike between 2000 and 2003.

The fatal crash rate on “diversion routes,” the largely two-lane undivided highways heavy trucks are now forced to travel, was 10 times higher than the Maine Turnpike and interstate routes, based on miles traveled. Accidents involving serious injuries were also less frequent on the turnpike and interstate than on diversion routes.

If the safety arguments aren’t enough, the transportation ministers of Nova Scotia, Prince Edward Island, New Brunswick and Newfoundland and Labrador last year wrote to the U.S. House and Senate Transportation Committee warning that the 80,000-pound limit was a hindrance to international trade.

Allowing Maine to follow the same rules as all its neighbors for three years while assessing safety data to allay concerns is a prudent approach worthy of broad support.