Goldsboro, N.C. — The North Carolina Department of Transportation says it is still not sure what is causing a 2.5-mile stretch of Interstate 795 to crack.

It could cost the state up to $1 million more for repairs before engineers even find out what the problem is.

The cracks surfaced soon after the 21-mile, $120 million highway from Wilson to Goldsboro opened two years ago.

A permanent fix was expected to be in place by the end of the summer, but DOT division engineer Ricky Greene says it could be the end of the year before the agency can fix the problem.

The added cost concerns state Rep. Ty Harrell, D-Wake, a member of the Legislature's Transportation Oversight Committee.

"We've got to figure out what the problems are before we just start throwing millions of dollars around to repair small patches of road. That eats away at our overall budget for greater infrastructure needs," he said.

The DOT and outside contractors have tested the road's surface extensively, and the Federal Highway Administration used deep-penetrating radar in an effort to provide answers.

So far, Greene says, there are none.

"This is a very long stretch, and we want to look at all of it from a risk-management basis to make sure what the extent of the problem is," Greene said.

It's possible more money will be required once crews identify the problem. Also uncertain is whether crews can fix just the cracked 2.5-mile stretch or if they will have to redo the entire highway. Some estimates have that alternative adding another $7 million to I-795's cost.