Falling Concrete Shuts Down B-W Parkway
Saturday, August 25, 2007
Concrete chunks from an overpass fell onto the Baltimore-Washington Parkway in Greenbelt yesterday, causing no injuries but leading authorities to close a section of the busy thoroughfare for several hours.
Just after noon, U.S. Park Police and Greenbelt police closed the parkway in both directions, as well as the Greenbelt Road bridge on Route 193, another significant commuter road. Officials with the National Park Service, which is responsible for the bridge, deemed it sound about two hours later.
The closures come less than a month after a bridge in Minnesota collapsed into the Mississippi River, killing 13 people and drawing attention to the safety of the nation's bridges.
William Schutt, a corrosion expert, said falling concrete is sometimes caused by rust and corrosion on a bridge's steel reinforcement bars. After examining photographs of the Greenbelt bridge, Schutt said de-icing salts might have caused reinforcing steel to corrode and expand, leading to cracks in the concrete.
"What should have happened is they should have detected the corrosion much earlier," said Schutt, president of a Philadelphia engineering firm that works with the Federal Highway Administration.
A 2005 inspection found two of the 1953 bridge's three key structural elements to be "satisfactory," which federal standards define as including "some minor deterioration," inspection data show. The third key element received a rating of "good," which can include "some minor problems."
The overpass and the southbound lanes of the parkway were reopened when the bridge was declared sound. The northbound lane remained closed until about 4 p.m. while workers used a hammer and a crowbar to poke at a crumbling three-foot section of the bridge, searching for loose concrete.
The closures snarled traffic as motorists were diverted onto the Beltway and local roads.
Sgt. Robert Lachance, a Park Police spokesman, said the Park Service would be responsible for ensuring that the bridge is safe. "On Monday they will do further inspection," he said, "but we have been told by the Park Service and the Federal Highway Administration that the bridge is safe."
Staff writer Michael Laris contributed to this report.