Vehicles pass a construction sign warning of delays on a road under construction in Brunswick, Maine, on Wednesday, May 12, 2010. Credit: Pat Wellenbach | AP

If there were a politically easy solution to Maine’s transportation funding woes, it would have emerged by now.

After years of shortfalls to fund road and bridge maintenance, and repeated asks for voters to approve $100 million t ransportation bonds, Maine has settled into an irresponsible pattern for providing this fundamental government service. With the creation and ongoing work of a transportation funding commission this year, there’s been reason to hope that lawmakers of both parties and the Mills administration may be willing to make some politically tough but necessary decisions.

So it’s discouraging that Republicans on the commission signaled that raising Maine’s gas tax is off the table for them moving into an election year. At the very least, a modest increase to the gas tax, the primary funding source for Maine’s highway fund, must be part of a multifaceted shift in how the state funds transportation maintenance.

Maine transportation funding comes from a mix of sources: the state’s highway fund, the federal government and bonding. The highway fund will support 39 percent of the projects in the Maine Department of Transportation’s two-year work plan. The gas tax accounts for 69 percent of that fund, and vehicle registrations and fees provide most of the remaining funding.

Maine’s gas tax is currently 30 cents per gallon, putting the state in the middle of the road compared with other states. The federal gas tax of 18.4 center per gallon has not been increased since 1993, and Maine’s gas tax has remained unchanged since 2011 when it was unwisely de-indexed. Those factors have undermined the effectiveness of this long-standing means to fund transportation infrastructure, both here in Maine and around the country. But that’s not the only force at work.

The gas tax’s efficiency and impact has also dropped as more and more people turn to more energy-efficient vehicles, including hybrid and electric vehicles — an otherwise encouraging trend. As a result, increasing the gas tax isn’t going to solve our transportation woes on its own. There also should be steps taken to make sure energy-efficient vehicles are equally contributing to the infrastructure funding.

Legislators, however, cannot completely abandon an increase to the gas tax, which remains a sensible source of revenue aiming to ensure the people using roads are also the ones paying to maintain them.

Suggestions from Republican members of the commission and others to move money from the general fund to the highway fund, use budget surplus funds or divert some vehicle purchase sales tax revenue specifically to the transportation shortfall should be part of the debate. But those potential measures should come in addition to a conversation about raising the gas tax, not in place of it.

The Maine Department of Transportation says the shortfall is now up to $232 million, with a steep 46 percent increase since a March estimate due in large part to increased construction costs. As correctly pointed out by Transportation Committee co-chair Andrew McLean, D-Gorham, this shortfall is “too substantial” to address without a broad compromise that employs several different approaches. He has submitted multiple bills in recent years with this balanced approach.

According to a Department of Transportation spokesperson, a one cent increase to the gas tax would generate $7.5 million in revenue. This cannot be the only approach, but it’s a straightforward place to start.

The trucking industry and other business groups support some level of a gas tax increase. Republicans officials must be too, just as Democrats must be willing to consider fees on electric vehicles and ways to shift general funds to road and bridge maintenance.

We do not have all the answers, but we know that repeatedly turning to bond packages while still staring down shortfalls is unsustainable — and we know that a gas tax increase has to remain an option. The road to more responsible transportation funding is going to take politically unpopular concessions from both sides of the aisle in Augusta.

The Bangor Daily News editorial board members are Publisher Richard J. Warren, Opinion Editor Susan Young, Deputy Opinion Editor Matt Junker and BDN President Todd Benoit. Young has worked for the BDN...