Lake Street Bascule Bridge Rehabilitation

Chicago, Illinois

DB Sterlin is working on the structural engineering aspects of the CDOT Lake Street Bascule Bridge Rehabilitation project. This includes designing the upper-level floor beams for the CTA, the steel and concrete for the fixed-span sidewalks, and the new bridge houses and exterior stairs. Additionally, we are responsible for miscellaneous structural design elements such as pit stairs, landings, and ladders, as well as concrete repairs for the exterior river piers and interior pit walls.

The Lake Street Bridge, built around 1914, is a double-deck bascule bridge that accommodates two lanes of traffic on its lower level and two CTA tracks on its upper level. The bridge’s superstructure consists of two “leafs” that extend from the substructures on either side of the river. Each leaf is made up of two identical main trusses that support transverse beams, which carry the load of the roadway and tracks. The bridge’s substructures are made up of a reinforced concrete pit that is cast in place and supported by four concrete caissons at each end of the bridge.