PHILADELPHIA — Note: The video is from February 2025.
Three Philadelphia-area bridges and one Bucks County span are among the 68 structures that the National Transportation Safety Board recommends be evaluated for risk of collapse due to vessel strike, according to a report the agency issued Thursday as part of its investigation of the Key Bridge collapse in Baltimore last year.
According to the NTSB report, the Walt Whitman Bridge, the Benjamin Franklin Bridge, the Betsy Ross Bridge and the Delaware River Turnpike Bridge should be evaluated to determine whether they are above acceptable level of risk guidelines established by the American Association of State Highway and Transportation Officials, or AASHTO.
The report, which was issued Thursday by the NTSB, found that the Key Bridge, which collapsed after being struck by the containership Dali on March 26, 2024, was almost 30 times above the acceptable risk threshold for critical or essential bridges, according to the AASHTO’s risk guidance.
The 68 bridges are owned by 30 entities across 19 states, according to the NTSB.
“Today’s report does not suggest that the 68 bridges are certain to collapse,” the NTSB said. “The NTSB is recommending that these 30 bridge owners evaluate whether the bridges are above the AASHTO acceptable level of risk. The NTSB recommended that bridge owners develop and implement a comprehensive risk reduction plan, if the calculations indicate a bridge has a risk level above the AASHTO threshold.”
The bridges listed by the NTSB were designed before the AASHTO guidance was established— like the Key Bridge —and do not have a current vulnerability assessment, the NTSB said.
The recommendations are issued to bridge owners to calculate the annual frequency of collapse for their bridges using AASHTO’s Method II calculation.
The AASHTO developed and published the vulnerability assessment calculation for new bridges on the National Highway System, in response to the NTSB’s investigation of the Sunshine Skyway Bridge collapse in Florida in 1991, the NTSB said.
At the time, AASHTO also recommended that all bridge owners conduct the vulnerability assessment on existing bridges to evaluate their risk of catastrophic collapse in the event of a vessel collision.
AASHTO reiterated that recommendation to states again in 2009, according to the NTSB.
Since 1994, the Federal Highway Administration, or FHWA, has required new bridges be designed to minimize the risk of a catastrophic bridge collapse from a vessel collision, given the size, speed and other characteristics of vessels navigating the channel under the bridge, the NTSB said.
The Key Bridge, which opened in 1972, was built before vulnerability assessments were required by FHWA, the NTSB said.
“The NTSB (report) found that had the Maryland Transportation Authority conducted a vulnerability assessment on the Key Bridge based on recent vessel traffic, it would have been aware that the Key Bridge was above the acceptable risk and would have had information to proactively reduce the bridge’s risk of a collapse and loss of lives associated with a vessel collision with the bridge,” the NTSB said.
The NTSB is also recommending FHWA, the U.S. Coast Guard and the U.S. Army Corps of Engineers establish an interdisciplinary team to provide guidance and assistance to bridge owners on evaluating and reducing the risk, which could mean infrastructure improvements or operational changes.
The 984-foot, Singapore-flagged cargo vessel Dali was transiting out of Baltimore Harbor when it experienced a loss of electrical power and propulsion and struck the southern pier supporting the central truss spans of the Francis Scott Key Bridge, which subsequently collapsed.
Six construction crewmembers were killed and another was injured, as well as one person onboard the vessel, according to the NTSB.
The Benjamin Franklin Bridge, built in 1926, is the oldest of the four Pennsylvania bridges listed in the NTSB report. The Delaware River Turnpike Bridge was built in 1956, the Walt Whitman Bridge in 1957 and the Betsy Ross Bridge in 1976.