WASHINGTON — The Senate is on the verge of passing legislation allowing trucks weighing up to 100,000 pounds to exit Maine’s side roads and drive back on to all of the state’s interstate highways.

The truck weight measure has been long sought by the Maine congressional delegation, state officials and many local residents worried about big rigs banned from the highway rumbling through intersections and past homes, businesses and schools.

Currently, trucks weighing more than 80,000 pounds can use only the Maine Turnpike and must use side roads elsewhere around the state.

The legislation co-authored by Sen. Susan Collins, R-Maine, and Patrick Leahy, D-Vt., to allow heavier trucks to use all of the state’s interstates was included in a broad package of 2012 spending measures the Senate is set to vote on as early as this evening, although the vote could be delayed until after next week’s recess.

Vermont, too, has been trying to overturn a federal ban on heavier trucks using the interstate. The provision authored by Collins and Leahy applies to just Maine and Vermont and gives both states permanent exemptions to the current federal ban on heavier trucks on those states’ interstate highways.

The truck weight provision is not in the House version of the spending bill, so proponents of the exemptions for Maine and Vermont still need to win inclusion of the measure as part of the final House-Senate version of the legislation.

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.

Sen. Olympia Snowe, R-Maine, and Rep. Mike Michaud, D-2nd, also have been long pushing legislation from a variety of approaches to give Maine a truck weight exemption. Snowe and Michaud – along with Rep. Chellie Pingree, D-1st, whose southern Maine district isn’t as directly impacted by the issue but who supports the exemption – back the provision won by Collins and Leahy in their roles as Senate Appropriations Committee members.

Maine lawmakers say that Maine businesses are at a disadvantage, because surrounding states such as Massachusetts and New Hampshire already have exemptions letting the heavier trucks use their interstates. And lawmakers, truckers and the Maine Department of Transportation say that six-axle trucks – the exemption for Maine would require heavier trucks to have six axles, not just five – are safe to drive on highways and operate more safely on highways than on side roads.

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.”

In that report, the department said that while heavier trucks are allowed to operate on about 22,500 miles of non-interstate roads in Maine, they cannot drive on about 250 miles of Maine’s 367 miles of interstate highways.

“This situation forces these semi-trailers to exit the controlled-access Interstate system and travel on secondary roads with numerous villages, intersections, driveways, schools, crosswalks and many other potential conflict points,” said the report, which added that the heavier trucks also use more gas and take more time to reach their destinations because of the interstate ban.

An average trip from Hampden near Bangor north to Houlton by a six-axle, 100,000-pound truck takes 2 hours and 55 minutes on Route 2 versus two hours and five minutes on I-95, with the truck burning 10 less gallons of diesel fuel on the interstate route, the report said. Using Route 2 instead of I-95 for that trip also means passing through more than 270 intersections, 30 traffic lights and 86 cross walks, and driving by 3,000 driveways and through nine school crossings.

It is “absolutely” safer to have bigger trucks on interstates rather than side roads, said Duane Brunell, a project manager in the safety office of the Maine Department of Transportation, in a phone interview today.

There are opponents – including the railroad industry – to Maine’s exemption and to the use of heavier trucks in general. Opponents say the heavier trucks tear up highways and the heavier weights make them unsafe to operate on any roadway.

“Bigger, heavier trucks take longer to stop, are more prone to roll over, and accelerate bridge and road destruction,” said a recent release by a coalition of safety organizations, including Parents Against Tired Truckers, the Truck Safety Coalition and Citizens for Reliable and Safe Highways.

Maine Department of Transportation officials and Maine truckers say a six-axle, near 100,000-pound truck is no more difficult to handle and stop than a five-axle, 80,000 pound truck because of the wider weight distribution and increased braking capacity.

Brian Parke, president and CEO of the Maine Motor Transport Association, said there are economic benefits for the trucking industry and customers to having heavier – which he says equates to more productivity not necessarily bigger – trucks able to haul loads more quickly down the interstates. Those are benefits in diesel gas savings and increased productivity and payloads that could add up to several millions of dollars a year total for the Maine trucking industry, Parke said.

Barry Pottle, owner of Pottle’s Transportation in Bangor, said six trucks in his 140-truck fleet can haul more than 80,000 pounds. They can be used to haul, for instance, bigger loads from paper mills trying to ship their products and materials more efficiently. Being able to get on all of Maine’s interstates would save money on fuel and time spent on the road.

But Pottle said the biggest benefit is safety.

“All we are asking for is to get these trucks off the back roads and on the interstate systems where they belong,” Pottle said.

Collins and the other Maine lawmakers who have been pushing the truck weight exemption have not received unusually heavy campaign contributions from the trucking industry, in the context of industry contributions to other lawmakers nationwide.

For instance, Collins, elected to the Senate in 1994, has received $37,712 from the trucking industry over her career, about $22,000 of it when she last ran for reelection in 2008 and none so far in the 2012 cycle when she is not up for reelection, according to figures compiled by the nonpartisan campaign research group Center for Responsive Politics.

But those figures do not put Collins for her career among the top Senate recipients of trucking industry contributions; and in 2008, 15 Senate candidates received more than Collins, though one was Hillary Clinton, then a senator from New York also running for president.

The Maine Motor Transport Association doesn’t have a federal political action committee, and thus can’t contribute as an association to federal lawmakers or candidates for federal office.

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