Interstate 70 in Washington County, Pennsylvania, has been sinking as much as a foot and a half during the night due to a Consol Energy coal mine underneath the highway, according to the Pennsylvania Motor Truck Assn.

The mining started in early May and will continue throughout the month. An official with the Pennsylvania Department of Transportation said drivers unfamiliar with the area, near the interchange with I-79, might not even notice the sinking. Officials have cut the speed limit to 40 mph and may shut down the highway if needed.