Why Did the Francis Scott Key Bridge Collapse So Catastrophically?

©iStock/WilliamSherman

When the loaded container ship Dali destroyed one of the Francis Scott Key Bridge's main support columns (see photo), the entire structure was doomed to fail. 

"Any bridge would have been in serious danger from a collision like this," said Nii Attoh-Okine, professor and chair of civil and environmental engineering at the University of Maryland.

Bridges work by transferring the load they carry ‒ cars, trucks or trains ‒ through their support beams onto columns or piles sunk deep into the ground. But they also depend on those support columns to hold them up.

Opened in 1977, the bridge was 1.6 miles long and was the world's third-longest continuous-truss bridge span, carrying about 31,000 vehicles a day.

Read more about the long-term impact the collapse will have on shipping and vehicle traffic all along the East Coast.