Any proposal to increase the state gas tax faces major hurdles this legislative year despite the crying need for more road funding. But the idea has gained a new advocate in the S.C. Alliance to Fix Our Roads. And the group is correctly framing the issue as one of “user pays.”

Simply put, the only people who pay gas taxes are those who use the highways. And that number includes a considerable percentage from out of state.

In fact, a recent report to the S.C. Department of Transportation estimated that as much as 40 percent of the state’s gas tax revenues come from out-of-state motorists and truckers.

Unfortunately, the 16-cent per gallon tax isn’t remotely adequate to the task of meeting the state’s transportation responsibilities.

Indeed, the state has a $29 billion shortfall in maintenance and new construction needs over the next 20 years, according to the report.

Meanwhile, the gas tax hasn’t been increased since 1987, and is one of the lowest in the nation. And the state’s road system is one of the largest.

Unless the situation is addressed, the gap between revenue and transportation needs will get only wider, and South Carolina will continue to fall further and further behind in its capacity to merely maintain its road system.

That’s particularly true for secondary roads, for which there are adequate funds only for a 119-year repaving cycle. That’s right — 119 years.

Fiscal conservatism is an important element of a responsible Legislature. But it has to be based on fiscal reality. Merely saying no to an increase in the gas tax fails to recognize the false savings inherent in delaying road projects indefinitely. The longer that basic maintenance is deferred, the more costly it ultimately becomes.

The Alliance recently made its case to a meeting of Palmetto State mayors, and urged them to join the effort to convince the Legislature to deal with the issue. Their efforts will have to include Gov. Nikki Haley, who also opposes an increase in the gas tax.

Gov. Haley complains that a portion of gas tax revenue is currently diverted to uses unrelated to transportation. Her executive budget would require $14.3 million of those expenditures to be funded with general revenues. That’s a good start toward more accountability.

In addition, Gov. Haley wants to provide $77 million in new money to the DOT from general fund revenue.

Nevertheless, given the number of out-of-state contributions, it’s hard to understand why any elected official wouldn’t support a gas tax hike. Having as much as 40 percent of the state’s road needs taken care of by non-residents is a deal too good to pass up, considering the need for road improvements. And considering that those motorists contribute to the wear and tear of South Carolina’s roadways.

Meanwhile, if the road-building powers that be would stick to priority projects, they could expect greater public support for increased funding to the DOT. The motoring public suffers when state roads aren’t up to standards. Bad roads translate into more auto repairs, as well as unsafe conditions that jeopardize their safety.

Too often, the state highway commission and the board of the State Infrastructure Bank have been willing to divert scarce resources to non-priority projects with strong political support, such as the extension of I-526 across Johns Island. It may not be a state priority, but it clearly is a SIB priority.

The commission and the SIB board should be restricted to supporting projects that are determined to be priorities under the objective ranking process approved in the 2007 DOT reform bill.

Making that a prerequisite would reduce the number of projects on the drawing board, and satisfy the public’s expectation that their gas taxes will be used to best advantage. And that should largely remove any impediment to raising gas taxes to a level that will enable the massive backlog of transportation needs to be reduced.