INDIANAPOLIS (AP) — A section of newly opened Interstate 69 in southwestern Indiana that was built atop an old coal mine has sunk several inches and will need repairs in the months ahead, a state highway official said.

Indiana opened the first 67 miles of the Evansville-to-Indianapolis highway in November from Evansville to Crane about 25 miles southwest of Bloomington. State transportation officials had long expected some settling along portions of the highway built over old coal-mining areas in Gibson and Pike counties.

Indiana Department of Transportation spokesman Will Wingfield told the Evansville Courier & Press that a 250-foot section of I-69 in Pike County that leads up to the Patoka River Bridge has sunk several inches, but currently poses no dangers for motorists.

He said that section will be fixed in the coming months, although a timetable for repairs hadn't been set.

"Even though I-69 is now open to traffic, construction is not completed. INDOT's maintenance and construction personnel that have been monitoring this, and the settlement is not an issue that requires an immediate response," Wingfield said.

He said the section that's settled was paved with dark asphalt designed to be more flexible than concrete.

Wingfield said the lead-up to the Patoka River Bridge was mined just before the highway's construction and transportation officials said that may have caused the sinking.

INDOT will work with its contractors to make repairs, which he said could entail something as simple as sealing the pavement and adding additional asphalt layers.

As the state prepared its plans for the 142-mile highway extension, its project team studied soil samples and contractors performed a process called "deep dynamic compaction" that involved dropping a 15-ton weight from 30 feet in the air.

Contractors used dark asphalt rather than lighter-colored concrete to pave those sections.