Seconds fat

A new traffic study funded by the N.C. Department of Transportation may have sounded the death knell for an eight-lane Interstate 26 Connector through West Asheville. The study found only a minimal difference in drive times between the six- and eight-lane options and appears to contradict the DOT’s long-running argument that eight lanes are needed to avoid unacceptable levels of congestion.

Last August (and again in November), the Asheville City Council asked the DOT to re-examine the data using a computer program called CORSIM (see “A Last Ditch Effort,” Nov. 24 Xpress). “CORSIM [an acronym for corridor simulation] is the recognized state of the practice for traffic simulation,” DOT Plan Review Engineer Nathan K. Phillips noted in a memorandum replying to Council’s August request.

Eight-laning, the new study found, would shave 9.6 seconds off the travel time from Interstate 40 to the North Broadway intersection during the afternoon commute, compared to the six-lane option. Driving the same route in the opposite direction, having eight lanes would save 17.4 seconds. The difference in morning drive times is too tiny for the CORSIM program to meaningfully measure, according to Stantec Consulting Services, which conducted the study for the DOT.

A congestion simulation that Asheville Traffic Engineer Anthony Butzek prepared based on the CORSIM study could loom even larger in derailing the eight-lane option. The congestion study rates the level of service for the six-lane alternative as C on most segments and never falling below D. Both those ratings are considered acceptable by the DOT. For years, however, the agency has argued for the eight-lane configuration, citing earlier studies that said fewer lanes would result in unacceptable congestion.

The incredible shrinking estimates

In 2002, when the DOT was making its case to local officials for an eight-lane connector, the agency maintained that 143,000 vehicles per day would be using that stretch of freeway in 2025. (According to the DOT, eight lanes have a carrying capacity of 138,000 vehicles per day; six lanes can carry 103,500 vehicles, and four lanes can accommodate 69,000 vehicles per day.)

The department radically altered this estimate in 2003, after a study that covered a larger area and used more realistic employment and population-growth projections produced a traffic estimate that was more than 30 percent lower (99,100 vehicles per day — well below what six lanes could handle). But the agency insisted that the extra lanes were still needed to avoid falling below a D rating.

Council member Brownie Newman (who, together with Butzek, had urged City Council to press for the new study) told Xpress: “The DOT is to be applauded for conducting this state-of-the-art traffic study. It’s hard to avoid the conclusion that continued advocacy for an eight-lane freeway will further delay the project, waste millions in taxpayer dollars and harm West Asheville. And for what? Eight seconds of drive time? It’s time to move on.”

Vice Mayor Carl Mumpower, meanwhile, said: “I pushed for further study because the DOT has not provided clear and consistent data upon which to solidify a recommendation. Hopefully this final effort will shine enough light on the facts that the majority of the community can land on a final lane configuration and press forward.” He added, “I don’t have a dog in the fight in terms of six or eight, but I do want us to make a fact-based choice on the right one for the job.”

Construction on the I-26 Connector project is scheduled to begin in 2012.

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