You’ve probably driven over one of these structurally deficient bridges in Mass.

The collapse of the Francis Scott Key Bridge in Baltimore last month underscored the fragility of vulnerable bridge infrastructure all across America.

In fact, hundreds of millions of people are crossing over structurally deficient bridges in the U.S. daily, including in Massachusetts. There are 450 bridges in the state classified as such, according to the Federal Highway Administration’s 2023 National Bridge Inventory. Other local reports have put the number above 600.

It’s estimated that these bridges in Massachusetts see more than 10 million crossings per day.

A bridge is determined to be structurally deficient when one of its key elements — the deck, superstructure, substructure or culverts — is deemed to be in poor or worse condition (a rating of 4 or lower). That doesn’t mean it’s going to collapse, experts say, but rather, state, municipal or federal officials are monitoring it closely.

Bridges meriting enough concern are typically posted with weight limits or closed entirely, said Phineas Baxandall, a transportation expert and interim president at the Massachusetts Budget and Policy Center. Catastrophic failures are exceedingly rare, he said.

“People can know that they are inspected regularly and (while) there are bridges that are in need of attention and investment for the future, if they were unsafe, regular state inspections would have closed the bridge,” Baxandall said.

The Commonwealth has identified needed repairs on 4,934 of 5,281 bridges tracked by the federal government, according to the American Road and Transportation Builders Association. The Massachusetts Department of Transportation’s bridge database tracks the condition of 8,044 state-and-municipally-owned bridges and culverts.

And while people expect safe bridges, they also often view “orange cones closing a lane” as a major inconvenience, Baxandall said. That makes completing bridge repairs a tricky balance between long-term safety and daily needs of the public. It’s especially challenging when Massachusetts’ infrastructure is significantly older compared to much of the country.

“We have an exceptional number of bridges that are getting past their normal, useful life, and so we have to expect a lot more investment to keep these bridges safe and sound in the future,” he said.

Most-traveled bridges in need of repair

In the summer of 2022, the Massachusetts Budget and Policy Center published an analysis of structurally deficient bridges in the state.

Among several alarming findings, it showed the average Massachusetts resident lives 1.7 miles from a structurally deficient bridge, and residents who are a racial or ethnic “minority” live an average of 1.3 miles away. Limited English-speaking households live even closer to these bridges.

Differing from Federal Highway Administration estimates by using more local data, the Massachusetts Budget and Policy Center report identified 644 structurally deficient bridges in the Commonwealth. At the time, in August 2022, 64 bridges in the state were closed.

The report also named the most trafficked bridges with a structural deficiency by county in 2022. State records today show replacements and repairs are currently in progress for several of them.

  • Barnstable County

Dennis, located on Main Street over Bass River

Built or reconstructed in 1935, 10,836 daily crossings

  • Berkshire County

North Adams, located on State Road over Hoosic River

Built or reconstructed in 1958, 15,081 daily crossings

  • Bristol County

Attleboro, located on Interstate 95 off-ramp over Farmers Pond/by Clifton Street

Built or reconstructed in 1969, 114,648 daily crossings

  • Dukes County

Edgartown, located on Katama Road by South Beach State Park

Built or reconstructed in 1850, 350 crossings daily

  • Essex County

Andover, located on Chandler Road over Interstate 93

Built or reconstructed in 1959, 134,835 daily crossings

  • Franklin County

Greenfield, located on Interstate 91/Route 2 intersection

Built or reconstructed in 1966, 31,409 daily crossings

  • Hampden County

Springfield, located on Springfield Expressway in Athol Junction

Built or reconstructed in 1969, 74,816 daily crossings

  • Hampshire County

Northampton, located on Interstate 91 over Mount Tom Road

Built or reconstructed in 1965, 49,564 daily crossings

  • Middlesex County

Lexington, located on Yankee Division Highway over Middlesex Turnpike (posted for limited load or capacity)

Built or reconstructed in 1961, 182,647 daily crossings

  • Nantucket County

No such bridges

  • Norfolk County

Braintree, located on Interstate 93 at Braintree Split

Built or reconstructed in 1978, 228,768 daily crossings

  • Plymouth County

Norwell, located on Pilgrim Highway over North River

Built or reconstructed in 1961, 69,956 daily crossings

  • Suffolk County

Boston, located on Mass Turnpike at Tremont Street

Built or reconstructed in 1965, 156,916 daily crossings

  • Worcester County

Worcester, located on Interstate 290 at Harrison Street/Canal District

Built or reconstructed in 1958, 144,751 daily crossings

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