Congress Street Bascule Bridge Reconstruction

The Congress Street Bascule Bridge is one of the few four leaf bascule bridges in the country and is located on a major route that serves the Chicago Loop. The bridge was completed in 1954 and spans the South Branch of the Chicago River. In 2010, the Illinois Department of Transportation (IDOT) embarked on a major rehabilitation of the movable bridge superstructure as well as the electrical and mechanical systems. Walsh Construction Company of Chicago Illinois (Walsh) was awarded the work for the project. Because of the complexity of construction work, IDOT required the contractor to retain the services of a Movable Bridge System Coordinator to work with the contractor to verify that all aspects of the work resulted in a fully operational bridge that met the requirements of the project specifications. Collins Engineers Incorporated of Chicago (Collins) was selected by Walsh to perform this work. The authors discuss the construction engineering design and construction techniques required to rehabilitate a movable bridge structure of this size and complexity. The construction engineering aspects of the work include modeling the truss under various stages of demolition and erection to determine stability and to ensure that there are no overstress conditions during the work, temporary jacking struts to replace load carrying members, pull down procedures prior to placing the leaf in operation, evaluation of crane loadings, bridge balancing both for temporary conditions and final completion, live load and anchor column adjustment, coordination of shop drawings and other submittals, and other temporary works required to complete the construction. The work required the close coordination between IDOT, the designer PB Americas, Walsh and Collins to complete the work efficiently.