Based on federal data, at least seven bridges in the US have a similar reach and size as the Francis Scott Key Bridge that recently collapsed. This makes them vulnerable to a similar collapse in the future.
US Bridges At Risk
According to the 2023 National Bridge Inventory of the Federal Highway Administration (FHA), several iconic bridges in the US have fracture critical members. This means that damage to just a single steel component could lead to the entire structure's collapse.
These bridges include the Golden Gate Bridge in San Francisco, the Verrazano-Narrows Bridge in New York City, St. John's Bridge in Oregon, the Lewis and Clark Bridge that links Oregon with Washington State, the San Francisco-Oakland Bay Bridge, the Chesapeake Bay Bridge, and the Tacoma Narrows Bridge. Most of the bridges with highest risk are situated in the Pacific northwest.
The Chesapeake bridge sees a daily traffic of around 72,000 vehicles, based on toll data from 2016. Huge container vessels also move beneath it.
As for other bridges, the Tacoma Narrows sees over 90,000 vehicles passing by; St. Johns sees over 22,000 vehicles traveling through; the Lewis and Clark bridge has around 21,400 vehicles moving through it.
What makes things more worrisome is that all of them are supported by piers, which are concrete island towers, that are vulnerable to the type of vessel impact that devastated the Key.
Based on a Wall Street Journal analysis of the National Bridge Inventory, the seven bridges were identified to be similar to the Key when it comes to construction and size.
However, there were also inconsistencies observed in the inspection data of the inventory. This could mean that other US bridges could also have similar risks.
Stronger Bridges
However, to build piers of bridges that are strong enough to endure such a container ship's blow, it might be equivalent to constructing a castle in a river, as noted by a senior civil engineer.
According to Bilal Ayyub, an engineer and former chair of the Infrastructure Resilience Division of the American Society of Civil Engineers, the alternative solution to safety is to construct barriers that prevent ships from nearing the bridge in the first place.
Ayyub explains that a bridge cannot be designed to endure the energy that is from a moving object that is massive as a barge. Rather, the former chair says that engineers make fenders, which are guardrail-systems, surrounding the piers. Ships could also be redirected away from such piers by dragging the constructed islands to surround the structure.
The engineer explains that what can essentially be done is to make the underwater ground have higher elevation for the ship to be grounded. It is designed to notify the operator of a nearby object.
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