A proposal to raise the weight limit of the nation's truck fleet after four decades of status quo is circulating in Congress. The bill would lift truck weight limits to 97,000 pounds for six-axle vehicles. The higher limit could lead shippers to divert more freight to trucks from railways, according to the Association of American Railroads. On the other hand, intermodal, which pairs rail and truck modes, "is an extremely fuel-efficient means of moving freight," said Ed Hamberger, AAR president. The Iowa Motor Truck Association opposes the change, because of road maintenance and safety concerns.