(The Center Square) – An ominous report identifies 20 bridges nationwide at serious risk of ship collisions, potentially resulting in a collapse like the one that brought down the Francis Scott Key Bridge in Baltimore.

A group of engineers from Johns Hopkins University in Baltimore analyzed the likelihood of ship/bridge collisions across the country, including the frequency of potential collisions.

Experts note that “ship strikes should be extremely rare” due to bridge design standards. The group says the annual chances of a bridge collapse stemming from a ship collision “should be less than 1 in 10,000.” However, the unsettling report finds that “some of the busiest bridges” in the country are “likely” to be hit by ships “within our lifetime.”

“With this investigation we wanted to know if what happened to the Key Bridge was a rare occurrence. Was it an aberration? We found it’s really not,” said Michael Shields, a Johns Hopkins engineer specializing in risk assessment and lead investigator of the National Science Foundation. “In fact, it’s something we should expect to happen every few years.”

Most of the bridges identified through the study are located in major metropolitan areas, including New Orleans, Houston, New York City and San Francisco, including one of the world’s most iconic bridges, the Golden Gate Bridge.

Among the bridges identified was the Delaware Memorial Bridge, which connects Delaware and New Jersey as part of Interstate 95. A potential collision with that bridge could have a devastating impact on the I-95 corridor from Maine to Florida, one the busiest in the country.

Before the Key Bridge collision, it was 15 years since the nation experienced a significant ship/bridge collision. However, engineers at Johns Hopkins believe chances could be high for a similar incident to the Key Bridge, leading to the group analyzing several factors surrounding shipping traffic and movements – specifically under bridges.

The report said, “The results revealed stark vulnerabilities for many bridges. Several bridges could expect a major ship collision – a collision strong enough to cause catastrophic damage or collapse – at least once every 20 to 50 years. Many others are likely to sustain a ship strike within 100 years.”

Shields highlighted the need to dramatically reduce the chances of repeating a disaster like Key Bridge collapse.

“To keep our bridges safe and operational, we want the chances of a collision strong enough to take down the bridge to be less than one in 10,000 in a given year, not one in a 100. One in 100 is extremely high,” Shields said. “If I look at the San Francisco Bay Bridge, we’re likely to see a major collision once every 22 years. That is huge. We want that number to be thousands of years. That’s tens of years.”

The most vulnerable bridges identified by the report include:

• Huey P. Long Bridge, Louisiana. Collision is expected once every 17 years.

• San Francisco–Oakland Bay Bridge. Collision is expected once every 22 years.

• Crescent City Connection, New Orleans. Collision is expected once every 34 years.

• Beltway 8 Bridge, Texas. Collision is expected once every 35 years.

• Hale Boggs Memorial Bridge, Louisiana. Collision is expected once every 37 years.

• Bayonne Bridge, New York/New Jersey. Collision is expected once every 43 years.

• Fred Hartman Bridge, Texas. Collision is expected once every 47 years.

• Martin Luther King Bridge, Texas. Collision expected once every 64 years.

• Sunshine Bridge, Louisiana. Collision expected once every 71 years.

• Rainbow Bridge, Texas. Collision is expected once every 71 years.

• Veterans Memorial Bridge, Louisiana. Collision expected once every 74 years.

• Chesapeake Bay Bridge, Maryland. Collision expected once every 86 years.

• Talmadge Memorial Bridge, Georgia. Collision is expected once every 88 years.

• Veterans Memorial Bridge, Texas. Collision expected once every 94 years.

• Delaware Memorial Bridge, Delaware/New Jersey. Collision is expected once every 129 years.

• Dames Point Bridge, Florida. Collision expected once every 152 years.

• Horace Wilkinson Bridge, Louisiana. Collision expected once every 198 years.

• Verrazzano-Narrows Bridge, New York. Collision expected once every 362 years.

• Golden Gate Bridge, California. Collision expected once every 481 years.

• John A. Blatnik Bridge, Minnesota/Wisconsin. Collision expected once every 634 years.

The engineers noted that according to their calculations, the Key Bridge “would have been among the 10 most vulnerable bridges.” Adding it would likely have been hit by a ship “within 48 years.” During the bridge’s 46 years, it had only sustained one other minor ship collision before the devastating collapse.

Despite the dire warning, Shields noted that “no two bridges are the same,” underscoring that a large ship collision doesn’t always equate to a bridge collapse.

The engineers suggested that to lower the risk of collisions, it is essential to “keep ship traffic away from piers,” adding that they should be outfitted with “robust protections,” including structural “dolphins.”

Following the 1980 deadly ship collision and collapse of the Sunshine Skyway Bridge over Tampa Bay, engineers incorporated several concrete dolphins to act as a barrier between ships and the bridge’s main supports.

Wednesday marks one year since the Key Bridge collapse, where the container ship Dali collided with the bridge in the early morning hours, killing six construction workers.