Rowan County’s legislative delegation isn’t alone in questioning the fairness of the state’s highway equity formula, which determines how state and federal funds are divvied up for highway projects.

As a Sunday story in the Post recounted, a Wake County-based planning board is now calling for the state auditor to take a closer look at how road funds are allocated, and it has offered some provocative statistics to support its call for a review. In Wake and several other counties, including Rowan, taxpayers are handing over more than they’re getting back in road funds, according to the study by the Capital Area Metropolitan Planning Organization. The shortfalls vary around the state. For example, using tax and expenditure data for the years 1991-2005, the group determined that Rowan County generated about $38.5 million annually in transportation tax revenues, and the state DOT spent about $31 million annually in Rowan, for a return of about 80 cents on the dollar. Cabarrus County had a return rate of about 66 percent; Iredell, 46 percent and Davidson County, 58 percent.

While some counties appear to be getting substantially less in highway spending than they’re generating in related taxes, others receive a premium on the taxes they pay on new car sales and state and federal fuel taxes. Madison and Tyrell counties experienced 500-plus percent return ratios; for Graham, it was 329 percent; Washington, Alleghany, Hyde and Chowan were all above or near 200 percent. In some cases, poorer counties with few people but high-mileage interstates or other thoroughfares may merit higher return ratios, but the broad discrepancies underscore why there’s longstanding suspicion that politics still affects where pavement dollars flow — and not enough is flowing to areas with crumbling roads and increasing congestion.

To arrive at its revenue figures, the Wake board used DOT traffic counts and average fuel consumption to compute an estimate for each county. State DOT officials say it’s difficult to pinpoint exactly how much each county pays in transportation-related taxes because gasoline taxes are collected at the wholesale level, rather than on a per-county basis, and they maintain they’re following guidelines previously developed by the state legislature.

Highway funding is a perennial topic in the legislature, and this looks like a year when it’s likely to percolate even more than usual, with both Piedmont and Triangle legislators frustrated over delayed projects. The Wake organization’s figures are likely to help fuel debate, since they support complaints that some rural, sparsely populated counties along the coast and in the mountains appear to be getting more than their share of funding, while other counties are falling further behind on maintenance and expansion. A thorough audit could either dispel lingering doubts about funding equity or show that the allocation system no longer works for the state’s rapidly growing counties and needs an overhaul.