The National Transportation Safety Board is calling on the U.S. Army Corps of Engineers to evaluate the Bourne and Sagamore Bridges for risk of collapse in the event of a vessel collision.
The Army Corps of Engineers was one of 30 bridge owners across the country called out by the transportation board for failing to have up-to-date information on the vulnerability of their bridges. That means that right now, the risk of collapse due to vessel collision for the Bourne and Sagamore Bridges is unknown.
This comes out of an investigation into last year's collapse of the Francis Scott Key Bridge in Baltimore by the National Transportation Safety Board, which killed six people. The investigation yielded a report that included a list of 68 bridges that are overdue for risk assessments, including the Bourne and Sagamore Bridges.
National Transportation Safety Board chair Jennifer Homendy explained in a press briefing Thursday that had Maryland conducted such an assessment on the Francis Scott Key Bridge, its catastrophic collapse last year that killed six people could possibly have been prevented.
“These bridge owners need to be looking at recent vessel traffic. Things have changed over time,” Homendy said. “Vessels have gotten bigger, heavier. In the 1950s, vessels had just 800 containers on them. Now we're talking 24,000 containers.”
At the press briefing, Homendy implored bridge owners to evaluate risk in order to help prevent another incident like the one in Baltimore.
“There's a safety deficiency here, a potential safety risk, and you need to take immediate action,” she said. “We will follow up with all of the bridge owners.”
But Homendy also emphasized that if a bridge is determined to be at higher risk, it does not automatically mean the bridge is at risk of imminent collapse.
“A risk level above the acceptable threshold doesn't mean a collapse from a vessel collision is an absolute certainty,” she said. “Likewise, a bridge design with a risk level below the acceptable threshold doesn't guarantee that a collapse from a vessel collision won't occur.”
The acceptable threshold for collapse risk is set by the American Association of State Highway and Transportation Officials (AASHTO).
The report issued “urgent safety recommendations” that tell bridge owners to use the methods laid out by AASHTO to calculate collapse risk. Then, they can use that information to make decisions about bridge safety.
“A screening process based on the estimated annual frequency of collapse can be used to identify and rank high risk bridges and to prioritize vulnerable structures for potential rehabilitation, retrofit, pier protection, countermeasures, or replacement,” Homendy said.
Army Colonel Justin Pabis, commander of Army Corps of Engineers’ New England District, said in a statement that safety is the top priority for the Army Corps of Engineers.
More detailed information from the Corps will come later, as they are still reviewing the report’s findings and recommendations, Pabis said.
Plans to replace the Sagamore Bridge are already underway. The Bourne Bridge is set to be replaced next.
Both bridges are 90 years old and are both “functionally obsolete,” according to the Cape Cod Commission. The Bourne Bridge has been deemed by the U.S. Army Corps of Engineers as “in poor condition,” while the Sagamore Bridge is “in fair condition,” per the Cape Cod Commission.
These ratings are not the same type of evaluation the National Transportation Safety Board report recommends.
