Southbound commuters on Falls Road encountered an 8-foot-wide hole yesterday that forced traffic into a single lane. The hole, 5 feet deep, was off to the right side of the road, opposite Brightfield Road, which is 1,000 feet south of Interstate 695.
This is the third time in the last six months that a hole has opened up in that area of Falls Road, leading some state highway officials to speculate that there might be a geological flaw underneath the road.
"As near as we can tell, it's a sinkhole," said Charles Harrison, the State Highway Administration's district engineer for Baltimore and Harford counties.
Dave Martin, a geologist for the Highway Administration, said sinkholes occur when "rocks develop cavities." Calcium carbonate, which underlies much of Baltimore County, "does dissolve -- not fast, but it does," he said.
The hole discovered yesterday was patched within hours, and geological surveys of the area will begin as soon as possible, highway officials said.
"You can look for sinkholes before they collapse, but it's a natural thing that you can't stop," Mr. Martin said. The first hole, discovered soon after a water main break in the area, was 80 to 100 feet wide and 12 feet deep. It was filled with 60 truckloads of flo-ash, a soupy material that hardens to fill up such holes.
The second hole was a minor one discovered during routine maintenance, but it left officials wondering how another one could have developed after so much material was used to fill up the first crater.
If a sinkhole is causing the problem, the solution would be to move street drainage systems away from the area. Mr. Martin said that would cost thousands -- and perhaps tens of thousands -- of dollars.