Raleigh, N.C. — Defective pavement is to blame for what the North Carolina Department of Transportation has said will be the biggest road construction project the Triangle has ever seen.

Work on an 11.5-mile stretch of Interstate 40 and Interstate 440 – from U.S. Highway 1 in Cary to U.S. Highway 64/264 in Raleigh – is expected to begin as early as this summer and will likely cause traffic headaches for the approximately 110,000 drivers who travel the roadway each day.

But Judith Corley-Lay, a pavement specialist for the state DOT, says the work is a necessary inconvenience because the roads were constructed in the 1980s using paving materials that react negatively to long-term exposure to water and breaks the cement.

"It's called alkali-silica reactivity, and it's a material defect that we did not understand at the time this project was designed and built," Corley-Lay said Thursday.

The problem wasn't discovered until about 10 years ago, and since then, the DOT has spent nearly $12 million putting temporary fixes, such as patches and overlays, in place.

"No matter what those short-term treatments are, the underlying material is continuing to degrade," Corley-Lay said.

To rebuild the highway, workers will need to dig at least 2 feet to remove and replace concrete and asphalt on the road, shoulders and ramps.

The DOT, which is expected to hire a contractor within the next month, estimates the cost of the reconstruction to be $170 million.

Once construction begins, its goal is to get at least 30,000 drivers to use alternate routes, alternate their work schedules or use alternate forms of transportation to cut down on traffic delays.

A final schedule of road closures isn't yet available, but the DOT has said it expects that information once a contractor has been hired and work begins.

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