What do we know about Baltimore's Francis Scott Key Bridge?
Port of Baltimore. Here's what we know about the collision:
BRIDGE HISTORY
The four-lane steel bridge opened in 1977 after five years of construction and spans 1.6 miles (2.6 km). It crosses the Patapsco River, where U.S. national anthem author Francis Scott Key wrote the «Star Spangled Banner» in 1814 after witnessing the British defeat at the Battle of Baltimore and the British bombing of Fort McHenry. It has 185 feet (56 meters) of vertical clearance.
Built at an estimated cost of $110 million, it allowed for more traffic lanes and carried lower operating and maintenance costs than a tunnel.
BRIDGE STYLE
The metal truss-style bridge has a suspended deck, a design which contributed to its total collapse, engineers say. The ship appeared to hit a main concrete pier, which rests on soil underwater and is part of the foundation.
«This type of bridge is not designed to redistribute loads in the event of a main pier collapsing and therefore videos show there is a progressive collapse of the bridge» in which one element fails after another, said Marina Bock, a structural engineering lecturer at England's Aston University.
PLANNED UPGRADES
Starting in the summer of 2025, the Maryland transportation agency planned to replace the bridge's deck and install a «fiberglass jacket protection system at the water pier columns,» an agency report says.
TRAFFIC AND TRANSPORT INFO
The bridge carries 11.3 million vehicles a year, the Maryland Transportation Authority
