NTSB warns of risk to 68 critical bridges

The National Transportation Safety Board identified 68 bridges in 19 states that cross over ocean-going vessels as vulnerable to collapse.

A recent study published by the Coalition Against Large Trucks (CABT) warns that congressional proposals to allow heavier trucks on the roads could cause significant damage to the country’s local bridges. However, trucks are not the only factor jeopardizing the integrity of bridge structures in the United States.

The National Transportation Safety Board (NTSB) released an analysis on March 20 identifying 68 bridges in 19 states that cross over ocean-going vessels as vulnerable to collapse. This report was conducted following the tragic collapse of the Francis Scott Key Bridge in Baltimore last year.

Among the findings, it was determined that the Francis Scott Key Bridge was “almost 30 times above the acceptable risk threshold for critical or essential bridges,” according to AASHTO guidelines. For this reason, these 68 bridges are highlighted as priorities, requiring immediate and critical attention.

Bridges in a vulnerable state

The NTSB stated that the 68 vulnerable bridges have not undergone recent evaluations that take into account the current traffic of vessels, meaning they present an unknown level of collapse risk due to vessel collisions. The NTSB recommends that the 30 owners of these bridges, including state transportation departments, toll and highway organizations, port and bridge authorities, as well as the U.S. Army Corps of Engineers, assess whether the bridges exceed the acceptable risk level according to AASHTO guidelines.

Although this does not mean the bridges are in imminent danger of collapse, the NTSB advised owners to develop and implement a comprehensive risk reduction plan to prevent any future dangers. The states with the most bridges in critical condition, according to the NTSB analysis, include:

New York with 13 bridges
Louisiana with 8 bridges
California with 7 bridges
Texas with 7 bridges
Ohio with 6 bridges
Massachusetts with 4 bridges
Pennsylvania with 4 bridges
Delaware with 3 bridges
Maryland with 3 bridges
Florida, New Jersey, and Oregon with 2 bridges each

Additionally, the list includes Georgia, Illinois, Michigan, New Hampshire, Rhode Island, Washington, and Wisconsin, each with 1 bridge.

Operational changes to safeguard U.S. bridges

The vulnerability assessment used by the NTSB requires specific data for each bridge and navigable waterway, such as the characteristics of vessel traffic passing under the bridge, ship transit speeds, vessel cargo characteristics, water depth, environmental conditions, bridge geometry, dock protection systems, and the ultimate lateral capacity of bridge piers.

The agency evaluated bridges that span navigable waterways and are at risk of collapse due to vessel conditions, identifying 34 bridges as “critical and essential” transportation infrastructure. These include the Golden Gate Bridge, the Sunshine Skyway Bridge in Florida, the Calumet River Skyway Bridge in Chicago, the Greater New Orleans Bridge, and the Mackinac Bridge in Michigan.

Furthermore, the year the bridges were constructed plays a significant role in this evaluation. For example, the New York State Department of Transportation owns the oldest at-risk bridges, such as the Brooklyn Bridge (1883), the Williamsburg Bridge (1903), and the Manhattan Bridge (1909). Also, the Memorial Bridge of the New Hampshire Department of Transportation (1921), which connects U.S. Route 1 to Maine, is among those classified by the NTSB as “critical and essential.”

The NTSB recommends the creation of an interdisciplinary team to provide guidance and assistance to bridge owners in assessing and reducing risks, which could involve infrastructure improvements or operational changes to safeguard U.S. bridges.