IN CAMPAIGNS for the General Assembly across Northern Virginia this fall, Republicans have been at pains to explain how they intend to address the No. 1 concern of many voters. Many GOP candidates acknowledge privately that any serious attempt to improve the transportation network requires new funding. In public, though, nearly all forswear raising taxes.

Since voters are highly educated and apt to notice double talk, Republicans have groped for sensible explanations. Unfortunately most of what they say doesn’t make much sense.

One popular idea is that the state can tap vast new revenue for transportation from offshore oil and gas drilling. Let us count the problems. One is the federal moratorium on offshore drilling on the Atlantic seaboard. Another is that virtually no exploration has been done in the area in 20 years; no one knows the size of the reserves or whether it would be economical to exploit them. Current law would reserve royalties for the federal government, with no revenue-sharing for the Eastern states (unlike with drilling revenue in the Gulf).

Then there’s the probable opposition of the Navy, which conducts large-scale exercises in coastal waters; NASA, which worries about interference with its operations at Wallops Flight Facility on the Eastern Shore; environmentalists; and Virginia’s neighbors, including Maryland, which worry about the risk to the Chesapeake Bay.

Even if those obstacles evaporated, the process of obtaining permits, surveying and drilling would mean Virginia would wait at least five years before it saw a dime — and that’s wildly optimistic.

Another favorite is that Virginia could find money for transportation by “reprioritizing” state spending. Richmond could, in fact, hack away at spending for education, public safety and health programs and repurpose the savings to build new roads, rails and bridges.

Unfortunately, virtually no Republicans admit that’s what they are intimating. Instead, they tend to fudge by suggesting — always without specifics — that hundreds of millions of dollars will materialize by eliminating waste, fraud and abuse. That’s not likely in a state widely seen as well managed and relatively corruption-free.

A few more sophisticated Republicans say that if the state won’t help, Northern Virginia will have to solve its transportation problem on its own. The idea is that, with Richmond’s authorization, Northern Virginia will tax itself, with the revenue staying in the region.

This at least acknowledges that new taxes are needed. It would also partly shift the political risk for raising taxes from lawmakers in Richmond to local boards of supervisors. Still, relatively few Republicans have embraced the idea, which suggests it wouldn’t go far without a major push from GOP leaders, including Gov. Robert F. McDonnell.

Virginia last raised its gas tax, the major funding source for transportation, in 1986. Inflation and fuel-efficient cars have depleted that stream of revenue. At current trends, there will be no money available for new road construction within the next few years. It’s time for politicians to look voters in the eye and acknowledge that reality.