Concrete falling from an overhead bridge - where deterioration found in 2005 has not yet been repaired - forced the closure of the Baltimore-Washington Parkway in Greenbelt yesterday and snarled traffic between the two cities for several hours.
The closing, which came less than four weeks after the collapse of the Interstate 35W bridge over the Mississippi River in Minneapolis, raised new questions about the safety of Maryland's infrastructure. One corrosion engineer warned that any instance of concrete falling from a bridge indicates "a serious problem."
The bridge that carries Route 193 over the parkway was closed about 12:10 p.m. after an individual called the U.S. Park Police to report debris in the roadway, said Fred Cunningham, who manages the parkway and nearby Greenbelt Park for the National Park Service. Both the parkway and Greenbelt Road, as that stretch of Route 193 is known, were closed.
Sgt. Robert LaChance, a spokesman for the park police, said no injuries or crashes were caused by the falling concrete, which he described as "fist-sized."
While the bridge is on a Maryland highway, it is owned and maintained by the federal park service rather than the State Highway Administration, Cunningham said. The bridge and parkway were closed until an inspector from the Federal Highway Administration cleared them to reopen at midafternoon after finding no imminent danger, he said.
Dave Buck, a spokesman for the state highway agency, said all lanes of the parkway and Route 193 were reopened by 3:35 p.m.
The bridge, built in 1953 and rebuilt in 1994, last received a full inspection in November 2005 and was found to be in "good condition," Cunningham said.
Ian Grossman, a spokesman for the highway administration, said all the major structural elements of the six-lane bridge were given 6's and 7's on the agency's 9-point scale - indicating it is in "fair to good" condition. But he said the inspection did reveal conditions "needing attention."
"There was some deterioration of concrete found during that inspection," Grossman said.
Cunningham said that as far as he knows, no repairs have been made to the concrete in the subsequent year and a half.
"I'm assuming it's in the plans to get done," he said. He added that the park service had given priority to some drainage problems found at the bridge.
Grossman said that short of finding "compromise to the structural integrity" of a bridge, the federal highway agency does not have the power to order repairs.
"It's the [National Park Service's] bridge. They have to make that call," he said. Grossman said the parkway bridges are inspected every two years.
William R. Schutt, a corrosion engineer and president of Matcor Inc. in Doylestown, Pa., called the problem of falling concrete "extremely serious." He said that 98 percent of the time, when concrete falls from a bridge it is the result of corrosion of the reinforcing steel.
"I would not be surprised in the least if this is a corrosion problem," Schutt said. "That bridge really, really needs examination."
Grossman said the federal highway inspector who examined the bridge yesterday "didn't find any major corrosion" on the steel rebar.
But the spokesman said the agency would send a team to do a comprehensive inspection of the bridge next week.
Average daily traffic figures for Route 193 were not available, but Greenbelt Road is a busy east-west artery connecting Greenbelt, College Park and Lanham in northern Prince George's County.
In the immediate aftermath of the closing, came several hours of confusion as state and federal spokesmen insisted the other government owned the bridge. Finally, in late afternoon, the park service confirmed its responsibility for the structure.
Cunningham said the park service owns all the bridges over the parkway between U.S. 50 and Route 175 in Howard County, except Route 32.
But the official said the maintenance responsibilities are sometimes divided up differently from one structure to another.
"I don't understand it either. It was something put into [agreements] prior to me being born," Cunningham said.