WASHINGTON — It still has a long road to travel before becoming law, but legislation allowing big rigs rumbling down Maine’s side roads to get back on the interstate highway advanced in the Senate today.

Legislation co-authored by Sen. Susan Collins, R-Maine, permanently allowing trucks weighing up to 100,000 pounds to use all of the state’s interstates has been included in a 2012 transportation spending bill approved by the Senate Appropriations Committee’s transportation subcommittee.

Collins, who is the top Republican on the subcommittee, wrote the legislation with Sen. Patrick Leahy, D-Vt., also a senior member of the Appropriations Committee, and their language was included in the overall transportation spending bill approved today by the subcommittee. Vermont, too, has been trying to overturn a federal ban on heavier trucks using the interstate, and the language in the subcommittee-approved bill applies to just Maine and Vermont.

Collins in a statement called the language being included in the subcommittee’s final spending bill an “essential first step toward a permanent fix for this very serious problem,” but noted that the bill must now clear the full committee and the full Senate. However, the same provision is not included in the House version of the 2012 transportation spending bill, so the Senate version would have to win out in a House-Senate conference committee on the final bill.

This is the latest attempt in an ongoing campaign by Maine members of Congress to to allow trucks weighing up to 100,000 pounds to use all of the state’s interstates. Currently, trucks weighing more than 80,000 pounds can use only the Maine turnpike and must use side roads elsewhere around the state.

Maine lawmakers say that Maine businesses are at a disadvantage now, because surrounding states such as Massachusetts and New Hampshire already have won exemptions letting the biggest trucks use their interstates.

Sen. Olympia Snowe, R-Maine, has introduced a bill that would allow states to seek individual waivers from the U.S Secretary of Transportation. Currently, individual states affected by the weight limits must seek an exemption through congressional legislation.

The Snowe bill would allow the secretary of transportation to establish three-year pilot programs on a state-by-state basis allowing heavier trucks to travel on their interstates. The pilot programs would require states to establish a safety committee – including department officials, highway safety advocates and representatives of the trucking industry – to determine whether the exemption should become permanent.

A bill in the House authored by Rep. Mike Michaud, D-2nd, also lets heavier trucks on the interstates in Maine and other states.

A Maine Department of Transportation report last fall concluded allowing trucks on all the interstates would “increase traffic safety, improve the environment, increase business competitiveness and reduce transportation infrastructure costs at no cost to the taxpayer.”

For a year, the big trucks were largely absent from the side roads. But last December a federal pilot program giving trucks weighing more than 80,000 pounds and up to 100,000 pounds permission to use all of Maine’s interstates lapsed. Once again, heavier trucks were only allowed on the Maine Turnpike from Kittery to Augusta.

There are opponents to letting trucks up to 100,000 pounds on the highways – or in some cases any roads at all. Among the major opponents to heavier trucks on the highways: the railroad industry and several key lawmakers, including Sen. Barbara Boxer, D-Cal.

MaineToday Media Washington Bureau Chief Jonathan Riskind can be contacted at 791-6280 or at: jriskind@mainetoday.com Twitter: Twitter.com/MaineTodayDC.