“In 2004, a bridge pier on the Lee Roy Selmon Expressway in Tampa, Florida sank 11 feet (more than 3 meters) while it was still under construction because of the complicated geology.”
That Tampa pier cost $90 million to fix and a year of delay. Bridges dump the whole load of a span onto a few piers, usually sitting in river mud. The Federal Highway Administration’s manual on driven piles runs over 500 pages and its drilled shaft manual 747. Bedrock is a simple idea, and geology doesn’t care.