ABSTRACT
During the early morning hours of April 31, 1994, a sinkhole opened in the roadway of Maryland Route 31, a two lane highway in rural central Maryland. The opening was approximately 9 meters (m) (30 feet [ft]) in diameter and 6–7 m(18–22 ft) deep. The location was just west of a gentle vertical curve in the highway so it was not easily visible to westbound motorists. An individual driving a small van was not able to take evasive action and a fatal accident was the result.
In order to quickly reopen the road to traffic, the sinkhole was immediately refilled with large rock and repaved. The result was a roadway that required weekly maintenance in order to remain operational. Following the temporary repair, extensive boring and geophysical studies were made in order to determine if more collapse was imminent. The sinkhole is developed in Wakefield Marble. A more comprehensive repair was made to the roadway in the fall of the year. The sinkhole was excavated to 22 m (70 ft) and the throat was plugged with concrete. The excavation was backfilled with rock and covered with geotextile to avoid soil infiltration into the rock. The road was then repaved with asphalt. Cost of repair alone was approximately $700,000.
