Overview of geology and foundations of bridges on the East Coast of USA

The densely populated corridor along the Atlantic coast between Boston and the capital of Washington, DC is home to many important bridges in the country. The regional geology is very old, tracing the history of the earth, with bedrock formed more than a billion years ago and surface geology that is very complex and variable. A thorough understanding of the local geologic and tectonic environment is essential to bridge foundation design, which has evolved tremendously from the underwater hand excavation of the caisson foundations of the Brooklyn Bridge to the sophisticated design of the new Woodrow Wilson Bridge. The paper presents local issues of subsurface conditions, seismic hazard, foundation solutions of old and new bridges, and retrofit schemes for seismic protection of historical bridges based on experience collected over more than a century from Mueser Rutledge Consulting Engineers.