DURHAM, N.C. — The N.C. Department of Transportation said Friday that a contractor is at fault for the crumbling pavement along an 11-mile stretch of Interstate 40 through Durham County.

In 2003, crews began widening I-40 to six lanes from the Durham Freeway to U.S. 15-501. The project, which cost $50 million, was completed last year, but the top layer of the interstate began crumbling about two months ago.

DOT officials said the problem exists because workers with Granite Construction failed to make 3-inch pavement expansion grooves along the I-40 stretch.

"The first year or construction season of work, the 3-inch cut was made," DOT spokesman Ernie Seneca said. "Then, in 2004, the 3-inch cut was not made, and we're trying to get to the bottom of this."

Seneca said Granite Construction should make the repairs and pay the costs.

"It's our contention Granite needs to address this and they need to make needed repairs," Seneca said. "Let's get on with the job ahead."

Granite Construction could not be reached for comment on Friday. The company has previously said its work crews did not receive proper instructions from DOT engineers, and it blamed the state for the problem.

Seneca said it was Granite's decision about how to proceed next.

"We're waiting to hear back from them," he said. "Bottomline, we want the work done and we can sort through whatever we need to along the process. But, we're gonna get the job done out there."