Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, February 28, 1995 TAG: 9502280118
SECTION: VIRGINIA PAGE: A-1 EDITION: METRO
SOURCE: MATT CHITTUM STAFF WRITER
DATELINE: LENGTH: Medium
That wasn't the case, but by Monday night the sinkhole that spread across the right lane of northbound I-81 was big enough to shut down traffic on the highway altogether for a five-mile stretch. All northbound traffic was re-routed onto U.S. 11 from exit 132 at Dixie Caverns to exit 137 at Wildwood Road in Salem.
The hole was first reported as a tiny crack around 3 p.m., according to State Police Sgt. V.C. Jones.
"At 6:30, it was the size of a five gallon bucket. Now it'll swallow the front of your car," Jones said.
And that's just the part you can see. Jones said the cavern extended beneath the pavement all the way across the left lane. That's why police shut down both lanes at 11:30 p.m.
Within minutes, exit 132 was packed with tractor-trailers streaming onto U.S. 11.
"You think this is bad, wait until you see it tomorrow," Jones said. The detour could last anywhere from one to three days.
And it gets worse. These things could show up all over the road.
"This whole area's like dirt spread over a cake pan," Jones said.
He said the pavement where the sinkhole occurred had been patched several times before.
Ernst Kastning, a Radford University geologist specializing in ground water who was on the scene, agrees. The area where the sinkhole occurred is called a karst: a stretch of soluble rock.
``I-81 goes right down the karst area of Virginia," Kastning said. Interstate 73, if it's built through the Roanoke area as planned, could have the same problems.
Caverns and sinkholes result from a process called piping, Kastning said. Water creeps through cracks in the earth and erodes caverns that grow out and up, until the ground above is too thin to support its own weight.
"You have to worry about terrain when you build highways, power lines, anything," he said. "Most times they don't worry so much about those things."
by CNB