PORTLAND — U.S. Sen. Susan Collins says allowable truck weights on Maine and Vermont interstates are scheduled to fall back to 80,000 pounds at the end of the day after the U.S. Senate abandoned a federal funding bill that included a provision allowing for heavy trucks.

Collins says a one-year pilot program to allow trucks of up to 100,000 pounds on Maine’s and Vermont’s federal interstate highways will expire Friday. An effort to extend the higher limit failed.

Supporters say allowing heavier trucks on federal highways promotes safety by keeping them off secondary roads.

But critics say heavier trucks compromise the safety of other motorists and damage highways and bridges.