RICHMOND — Upper Dublin Road, between Route 41 and the Hancock town line, is closed after a sinkhole opened in the roadway Tuesday.

The hole, which is roughly 15 inches wide at the surface but expands to a 5-foot round opening at the bottom, formed as a result of a deteriorated culvert beneath the road, according to Richmond Highway Superintendent Peter Beckwith.

Richmond Department of Public Works Superintendent Pete Beckwith pulls up a photo on his phone of the outer view of a sinkhole on Dublin Road when his crew arrived at the site on Tuesday morning. The compromised section of the road expanded significantly under the initial hole in the asphalt.

“The pipe rotted out and deteriorated, and as the water came through, it washed all the fines out, and it finally fell through,” Beckwith said. “That's why it cones out.”

As of Tuesday morning, highway crews were working to clear debris from the hole, though progress has been slow. Beckwith said the timeline to reopen the road depends on how quickly crews can safely clear and shore up the site. He estimated it could take "a couple days" to get the road patched enough to reopen.

Upper Dublin Road between Route 41 and Hancock is closed after a sinkhole opened on the road, the town announced Tuesday.

Beckwith said he plans to insert a smaller 18-inch culvert inside the existing 24-inch culvert as a temporary fix to get water flowing and the road open again until a permanent DEP-standard replacement can be permitted and installed.

Richmond Department of Public Works Superintendent Pete Beckwith, right, works with his crew to install a temporary culvert pipe that will run under the upper section of Dublin Road where a sinkhole opened on Tuesday.

The Richmond Fire Department was notified about the hole Monday night, Beckwith said, and he has declared an emergency to fast-track the replacement plan and coordinate with conservation officials.

Residents should follow the detour through Hancock until a temporary fix is in place, he said.

Beckwith said there are no broader public safety concerns related to the sinkhole.