FREDERICK, Md. (Map, News) - A sinkhole 14 feet wide and 20 feet deep collapsed one lane of Interstate 70 Thursday, backing up westbound traffic for at least a mile during the morning commute, the State Highway Administration said.

The agency closed both westbound lanes and directed drivers to use the left-hand shoulder or detour through Frederick, a city of 59,000 about 45 miles west of Baltimore.

SHA spokesman David Buck predicted the highway would fully reopen Friday morning.

"It's going to take us quite a while to fill the hole with rocks and grout," Buck said.

The sinkhole was in a quarried area prone to sinkhole formation. Buck said heavy rain last weekend may have dissolved some of the limestone and dolomite bedrock, creating subterranean voids.

"It's the most prevalent area where we've had sinkholes over the past 20 years," Buck said.

The agency closed the right-hand lane at about 7 a.m. after workers noticed a surface anomaly, Buck said. It widened into a depression 2 1/2 inches wide and 10 feet long before collapsing, he said.

Sinkholes also disrupted I-70 traffic in the area in October and November 2003, when several voids near the highway prompted ramp closures.

In the summer of 2003, a four-lane suburban road in Frederick was closed for six weeks while workers filled a sinkhole 12 feet deep and 32 feet wide.