Virtual Tour - Building the foundation
The first important task for the Mississippi River Bridge project was building the foundations. Like a house, the foundation of the bridge helps support the structure and keeps the bridge sound. The Mississippi River Bridge is constructed to have a 100-year life span (the bridge is expected to last 100 years without requiring significant renovation or reconstruction).
Overall, designers used drilled shafts for the foundations of the bridge. Drilled shafts are huge columns of concrete and steel that extend into the bedrock under the bridge. The drilled shaft looks something like this: