Trade groups are sparring over whether lawmakers should permit larger trucks on the roads, a dispute that comes as Congress weighs asking the Department of Transportation to release all findings evaluating the impact of longer trucks.

Proponents of increasing the national twin-trailer length from 28 feet to 33 feet say that the larger trailers would be more efficient and could help address a truck driver shortage by holding 18 percent more freight. Opponents warn of possible safety hazards and say the larger trucks would damage infrastructure.