Could a bridge collapse similar to Baltimore happen in Pittsburgh?

Barges have struck many bridges in the Pittsburgh region over the years, but none of the collisions caused major structural damage to any of the river spans, a local bridge expert said Tuesday.

Following Tuesday’s collapse of the Francis Scott Key Bridge in Baltimore, Allegheny County Public Works Director Stephen Shanley noted that waterway traffic is much different in Western Pennsylvania.

Shanley said it is “extremely unlikely” that a county-owned bridge would collapse after being struck by a barge or boat.

He said such collisions occur almost every year in Western Pennsylvania.

The collapse in Baltimore happened after a massive cargo ship hit one of the Francis Scott Key Bridge’s piers. Shanley said the scale of that has never been matched in Pittsburgh.

“It is extremely unlikely that we would face a similar situation to what happened in Baltimore this morning, because large cargo ships do not use our major waterways,” Shanley said. “It is possible that barges hitting one of our bridge piers could cause damage, but barges are not nearly as large or carry as much weight as a cargo ship.”

He said barges can get loose from towboats or riverbanks during flooding that raises water levels and increases the speed of a river. They tend to drift downriver and can smash into bridge piers.

Shanley said he remembers when barges hit the Rankin bridge in 2018 and the inspection work that he and his crew did before the bridge could be reopened. The bridges reopened the same day.

He said there are a number of factors that dictate how watercraft can damage bridges, including weight, speed and impact.

A lone barge has 1,750 tons of carrying capacity, and a 15-barge towboat can weigh up to 26,250 tons, according to the Louisville office of the Army Corps of Engineers.

It’s unclear how heavy the Dali cargo ship was at the time of the crash, but its weight can reach a maximum of nearly 117,000 tons.

Maryland Gov. Wes Moore said Dali was traveling about 8 to 9 knots when it struck the Francis Scott Key Bridge.

Towboats carrying coal barges are among the slower water vessels, typically traveling about 5 knots when propelled. A loose barge usually moves slower.

Pingbo Tang, an associate engineering professor at Carnegie Mellon University, said the Dali container ship must have had immense force to knock down the Francis Scott Bridge. He said it was hard to imagine similar circumstances in the Pittsburgh area.

He said Pittsburgh’s inland waterways are likely to have more predictable currents and slower winds that might impact water vessels. And Tang noted the large difference of weight and speed of barges compared with container ships.

“The impact from those kinds of ships is much higher than what we are likely to see in Pittsburgh,” he said. “A barge cannot achieve that.”

There have been several incidents over the years where barges have collided with Pittsburgh-area bridges, but no major bridge damage has been reported. They include but are not limited to:

• Four barges broke free and hit a Neville Island railroad bridge in April 2011.

• A barge hit the Smithfield Street Bridge in April 2012, and another barge sank.

• Fifteen barges were set loose near Rankin in May 2018, with some striking the Rankin Bridge and at least two others sinking.

• A dozen barges became loose near the Liberty Bridge in January 2019, with at least one striking the Liberty Bridge and others possibly hitting the Fort Pitt and Smithfield Street bridges.

• A barge slammed into the Smithfield Street Bridge in December 2019, causing a closure.

• The McKeesport-Duquesne Bridge was shut down for several hours in May 2021 after a possible barge strike.

Shanley said Allegheny County has invested $341.7 million on bridge work. He said the county has completed 144 major bridge projects, including rehabilitations of the three sister bridges in Downtown, the 16th Street Bridge, the 10th Street Bridge, the Rankin Bridge, the William D. Mansfield Memorial Bridges in Glassport, and the Fleming Park Bridges in Stowe Township.

All bridges in the Pittsburgh area that span the Allegheny, Monongahela or Ohio rivers are currently graded in fair or good condition by PennDOT.