The Wacker Drive viaduct reconstruction project was a massive undertaking to increase the structure’s safety and longevity, involving the reconstruction of a multi-level viaduct structure carrying upper and lower level traffic along the Chicago River. In total, the reconstructed Wacker Drive Viaduct is 2,900 feet-long and 140 feet-wide, equaling more than nine acres.
The new viaduct deck was designed as a cast-in-place concrete slab, post-tensioned in both directions, providing exceptional flexibility in the design of every major project component while saving weight to allow the re-use of the original drilling shafts. The innovative post-tensioning system design implemented on the project provides zero tension under all service loads with a 100-year design life and minimal required maintenance. From design to construction, this roadway, bridge and tunnel project is one of the most complicated ever completed by the City of Chicago and involved complex staging in order to maintain access to over a dozen skyscrapers on the Chicago River, while keeping 60,000 vehicles and 150,000 pedestrians moving through every day.