You’re familiar with the “mystery traffic jam.” You inch along bumper-to-bumper and when traffic finally flows, you can’t see why it stopped. There’s no sign of an accident or construction.

Often, it’s just a case of too many vehicles on the road at once.

The Triangle could see more of these bottlenecks as the region’s population and traffic grow faster than its roads. But the cause of those slowdowns, though invisible, may not be mysterious. It may be traceable to what’s happening today – a quartet of Republican Wake County commissioners standing in the way of expanded Triangle transit options.

On Tuesday, farsighted Orange County voters approved a half-cent sales tax increase that will expand the county’s bus service and start collecting dollars for light rail projects. In Durham County, voters gave a green light to a similar plan last year. But in Wake County, the Triangle’s most populous county, a proposed $3 billion, 25-year transit plan and the half-cent tax to support it hasn’t been able to find a place on the commissioners’ agenda, let alone the ballot.

The Wake Transit Plan calls for roughly doubling the existing bus service as its initial phase. It would launch rush-hour commuter trains from Durham through Research Triangle Park and Raleigh to Garner, and eventually start light rail service with a line from northeast Raleigh through downtown Raleigh to Cary.

The four-member majority on Wake’s Board of Commissioners has refused to set a hearing on the plan. They’ve held it off the agenda for months by asking the plan’s proponents to answer to a long list of questions. Some of the questions have come from the John Locke Foundation, a conservative-libertarian group so adverse to paying for mass transit it might be more accurately called the Gridlock Foundation.

Supporters of mass transit have responded with a thick stack of documentation. It has been greeted with inaction.

The Republican commissioners’ reluctance reflects their opposition to tax increases and their suspicion that expanded mass transit would be an overly subsidized, liberal indulgence in the suburban, car-centric Triangle. But as other Triangle counties go forward, it is their delay that’s becoming the ideological indulgence. It’s costing Wake County in dollars and lost time to forgo linking to the transit web emerging to its west.

Expanding transit isn’t an exercise in spendthrift, utopian engineering. It’s a practical response to a vital need. It’s favored by almost all of Wake’s 12 municipalities and the region’s big employers. They want it to be easier for their residents and employees to get to work where they can do something more productive than sit in traffic.

Tuesday’s election, in which the two contested Wake commissioner races were won by Democrats who are transit supporters, signals that voters are at least open-minded on the issue. It’s time for the commissioners board to give the plan a hearing that could lead to a transit tax referendum next year. Wake voters deserve a chance to decide whether they want to pay a little more today to make it easier to get around the Triangle tomorrow.