EIGHT major bridges in the United States are at risk of suffering a similar Baltimore-style disaster after huge vulnerability was spotted across the board.
Six people are believed to have died after the 1.6 mile Francis Scott Key Bridge snapped and crumbled into the water after it was hit by a container vessel.
It is feared last week's tragedy could now repeat itself after an urgent warning revealed eight other bridges in the US run a similar risk of collapsing.
All but one are older than the Key, and all have "fracture critical members", which means that even the breakdown of a single steel component in tension might result in a collapse, The Wall Street Journal reports.
Jennifer Homendy, chair of the National Transportation Safety Board, which is investigating the tragedy, told a press conference last Tuesday that the Key Bridge is one of more than 17,000 "fracture critical" bridges.
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Data suggests that many of these are smaller bridges than the Key, and are located away from the coast.
A bridge that is fracture-critical isn’t unsafe, according to engineers, but it lacks redundancy in its load-bearing design.
Commercial vessels are growing bigger by the minute, especially since the Panama Canal was widened in 2016, allowing enormous ships to enter East Coast ports from Asia.
The findings could put major US bridges and American commerce altogether in a complicated dilemma as these bridges may not be suitable to accommodate giant ships.
The Francis Scott Key Bridge, which opened in 1977, was built with a vertical clearance of more than 180 feet to accommodate huge container ships entering the port of Baltimore.
The bridge crossed the Patapsco River at a width sufficient to allow ships to navigate a 1,100-foot waterway between its piers.
Few bridges provide such ample space, and even fewer may see massive container ships transit, depending on channel depth and port capacity.
Other bridges may accept larger ships, but with less space.
Today, federal requirements mandate that bridges spanning navigable waterways be secured from potential vessel strikes.
Among the precautions are "dolphins", or independent barriers, designed to divert a wandering ship away from a bridge's piers, and "fenders" which connect to piers and cushion a vessel's impact.
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The Key Bridge pre-dates these requirements, although it was designed with a system of concrete and wood shields around its vertical supports to withstand a container ship collision in 1980.
The eight bridges at risk are part of major transportation systems in California, Maryland, Oregon, New York and Washington.
These include the twin spans of the nearby Chesapeake Bay Bridge, in Maryland, San Francisco’s Golden Gate Bridge and the Verrazzano-Narrows Bridge in New York.
Tacoma Narrows Bridge, Washington
The Tacoma Narrows Bridge, located in Washington State, USA, gained fame due to its dramatic collapse on November 7, 1940, just a few months after its completion.
The bridge's failure was attributed to a phenomenon known as aeroelastic flutter, where strong winds caused the bridge to oscillate violently until it ultimately collapsed into the Tacoma Narrows strait below.
This event led to advancements in bridge design and engineering to prevent similar disasters in the future.
Lewis and Clark Bridge, Oregon-Washington
The Lewis and Clark Bridge spans the Columbia River, connecting Rainier, Oregon, and Longview, Washington.
It was named after the famous explorers Meriwether Lewis and William Clark, who travelled across the American West in the early 19th century.
The bridge was opened in 1930 and underwent significant renovations and upgrades over the years to accommodate increasing traffic and safety standards.
It serves as a vital transportation link between Oregon and Washington, facilitating trade and travel between the two states.
St. Johns Bridge, Oregon
The St. Johns Bridge is an iconic suspension bridge located in Portland, Oregon, spanning the Willamette River.
It was completed in 1931 and is known for its distinctive Gothic-style towers and elegant design.
The bridge was named after the nearby St. Johns neighbourhood in North Portland.
It serves as a crucial transportation link, connecting the industrial area of Northwest Portland with St. Johns and the surrounding neighbourhoods.
The St. Johns Bridge is also renowned for its picturesque views and is a popular spot for sightseeing and photography.
Golden Gate Bridge, California
The Golden Gate Bridge is one of the most iconic landmarks in the world, located in San Francisco, California.
It spans the Golden Gate Strait, the entrance to the San Francisco Bay from the Pacific Ocean.
Completed in 1937, the Golden Gate Bridge is renowned for its stunning Art Deco design, vibrant orange colour, and breathtaking views of the bay and the city skyline.
The bridge stretches for 1.7 miles and features two majestic towers that rise 746 feet above the water.
At the time of its construction, it was the longest suspension bridge main span in the world, a title it held until 1964.
The Golden Gate Bridge serves as a vital transportation link for commuters and tourists alike, connecting San Francisco to Marin County and the North Bay region.
It is also a beloved symbol of San Francisco and a popular tourist attraction, drawing millions of visitors each year to walk, bike, or drive across its span and marvel at its beauty.
Additionally, the bridge has been featured in numerous films including Superman (1978) and James Bond - A View to a Kill (1985).
San Francisco-Oakland Bay Bridge, California
The San Francisco-Oakland Bay Bridge is a vital transportation link connecting San Francisco and Oakland, California, across the San Francisco Bay.
It consists of two main spans: the eastern span, which connects Oakland to Yerba Buena Island, and the western span, which connects Yerba Buena Island to San Francisco.
The bridge originally opened in 1936 and underwent significant retrofitting and renovations over the years to ensure its structural integrity and seismic safety.
The Bay Bridge is an essential artery for commuters and freight traffic in the Bay Area, playing a crucial role in the region's transportation network.
George Washington Bridge, New Jersey - New York
The George Washington Bridge is a major suspension bridge that crosses the Hudson River, connecting Fort Lee, New Jersey, with the Washington Heights neighbourhood of Manhattan in New York City.
It is named after George Washington, the first President of the United States, and is often referred to simply as the "GW Bridge."
Completed in 1931, the George Washington Bridge has a total length of approximately 4,760 feet and features two levels of traffic, with a total of 14 lanes.
It is one of the busiest bridges in the world, accommodating millions of vehicles each year and serving as a crucial transportation link between New Jersey and New York.
The bridge's distinctive steel towers rise 604 feet above the river, and its elegant Art Deco design has made it an iconic symbol of the New York metropolitan area.
In addition to vehicular traffic, the George Washington Bridge also accommodates pedestrians and cyclists, with walkways located on both sides of the bridge offering stunning views of the Hudson River and the Manhattan skyline.
Verrazzano-Narrows Bridge, New York
The Verrazzano-Narrows Bridge is a suspension bridge that spans the Narrows, the strait between the boroughs of Staten Island and Brooklyn in New York City.
It was named after the Italian explorer Giovanni da Verrazzano, who was the first European to sail into New York Harbor in 1524.
Opened in 1964, the Verrazzano-Narrows Bridge has a total length of approximately 4,260 feet and is one of the longest suspension bridges in the world.
It consists of two levels, with a total of 13 lanes of traffic, providing a vital transportation link between Staten Island and Brooklyn, as well as connecting these boroughs to the rest of New York City.
The bridge's towers rise 693 feet above the water, and its elegant design has made it a prominent landmark in the New York City skyline.
The Verrazzano-Narrows Bridge also offers stunning views of the harbour and the surrounding area, attracting tourists and photographers alike.
Chesapeake Bay Bridge, Maryland
The Chesapeake Bay Bridge, often referred to as simply the Bay Bridge, is a major bridge complex spanning the Chesapeake Bay in Maryland, USA.
It consists of two parallel spans: the original span, known as the William Preston Lane Jr. Memorial Bridge (commonly called the "Bay Bridge"), and the newer span, officially named the Governor Harry W. Nice Memorial Bridge.
The original Bay Bridge, opened in 1952, connects Sandy Point near Annapolis on the western shore of the Chesapeake Bay to Kent Island on the eastern shore.
It spans approximately 4.3 miles and features two main spans, as well as low-level causeways and high-level bridges.
The newer span, opened in 1973, is located to the north of the original bridge and provides additional capacity for traffic crossing the bay.
It is part of the wider Chesapeake Bay Bridge-Tunnel system.
The Bay Bridge complex is a vital transportation artery for the state of Maryland, providing a direct route between the eastern and western shores of the Chesapeake Bay.
It carries heavy volumes of traffic, particularly during the summer months when tourists travel to Maryland's eastern shore beaches.
