Get news updates from WGBH
Wed June 5, 2013
Bridge Collapse Sparks Questions Over Bridge Safety in Mass.
The recent bridge collapse in Washington State renewed discussions about America’s aging infrastructure. Massachusetts ranks in the middle of the country when it comes to the condition of its bridges.
People have been crossing bridges over the Charles River for more than 100 years. When the first bridges were designed, they were a marvel- creating opportunity for economic development. About a quarter million of us depend on them as part of our daily commute to work, school and to our homes on either side of the Charles River.
Nine percent of the 5,100 bridges in Massachusetts are considered structurally deficient, including several over the Charles River, according to Frank DePaola, the highway administrator for the Massachusetts Department of Transportation.
"Structurally deficient means that at least one portion of the bridge – and we divide the bridge into three major categories: the substructure, the foundation, the superstructure, which is the actual frame or skeleton of the bridge – if anyone of those three components fails to meet design or loading criteria, the bridge will be deemed structurally deficient," DePaola said.
Northeastern University civil and environmental engineering professor Ming Wang went with me to visually inspect the Charlestown Bridge, a rusty truss bridge that crosses the Charles River, connecting Charlestown to Boston’s North End. The bridge has six lanes, but two of them are blocked off and there’s a sign posted that reads “No Trucks”.
Wang found the Charlestown Bridge to be structurally deficient- marked by corroded beams that he said were beyond repair. It looked as if the bridge had been patched up in a piecemeal sort of way. Underneath the bridge are steel beams that are rotting away. Other, newer, redundant beams are carrying the weight.
"In this case because of redundancy it seems to be safe, but from what I see the corrosion is really ugly, and its time to repair by stripping the paint," Wang said as he flaked off some of the rusty paint on the surface of the beams.
Stripping the paint from the Charlestown Bridge will not be easy, because it most likely contains lead, Wang said.
The Mass DOT spends about $450 million a year on bridge projects. But not all of the bridges in Massachusetts are maintained by the state. Many of them are owned by cities and towns, which have a lot less money for repairs.
"We inspect every bridge at a minimum once every two years. Once we deem a bridge structurally deficient, we inspect it every year," DePaola said.
Because of its structural problems, the Charlestown Bridge is inspected by the state DOT every 6-months.
"We try to take care of those that have the highest exposure. The highest risk," DePaola said. "We don’t have the financial resources to go out and replace them all. We’re trying to focus the resources we have on those that give us the best returns and are the most critical for us to address and we’re working our way down the priority list."
Rob Rottenbucher, the supervising structural engineer for the City of Boston, said the Charlestown Bridge is on its priority list and a bridge re-design is expected to be finished in 2015.
Until then, if you drive one of the 40,000 vehicles that cross the Charlestown Bridge every day, and you are wondering if the bridge is safe, Rottenbucher said it is.
"We have a term for bridges that are unsafe, and that term is 'closed'," he said.
There are 34 bridges closed in Massachusetts, including one in Boston.
Interactive Map: The State Of Our Bridges
BOSTON PUBLIC RADIO