Chicago — Reconstruction of Wacker Drive/Congress Parkway in downtown Chicago was the winner of the 2014 Grand Conceptor Award for the best engineering achievement of the year by the American Council of Engineering Companies (ACEC) as part of the organization’s 2014 Engineering Excellence Awards program.
The ACEC competition recognizes outstanding projects designed by engineering firms across the United States. Parsons Brinckerhoff provided construction management services on a section of Wacker Drive from Randolph to Monroe streets. In addition to Parsons Brinckerhoff, the project team for the entire reconstruction included TranSystems, Alfred Benesch & Co., T.Y. Lin International, Burns & McDonnell, Infrastructure Engineering, and Lochner.
In announcing the award, ACEC stated: “Trailblazing engineering totally reconfigured a primary downtown Chicago bi-level traffic interchange, while keeping 135,000 vehicles and 150,000 pedestrians moving through the construction zone each day … By effectively accommodating heavy loads, unbalanced spans and geometric anomalies, the 10-year, $300-million project is a testament to superlative transportation innovation.”
Built in 1955, sections of Wacker Drive started to show severe deterioration of the roadway surface. Corrosion of the reinforced steel as well as the spalling of the concrete cover were just some of the issues that needed to be addressed. Antiquated ramps, inadequate roadway widths, and low clearances that prohibited larger delivery trucks from accessing businesses were other items that needed reconstruction.
The Chicago Department of Transportation decided to replace the aging viaduct with a biaxially post-tensioned, high-performance concrete slab structure that would resist chemical assault from deicers and hold up for the next 100 years. The project involved reconstruction of upper and lower Wacker Drive and the major interchange with Congress Parkway, replacement of the viaduct, and new access ramps. It included rehabilitation of the Randolph, Washington, and Madison Street bascule bridges over the Chicago River; new ventilation elements for lower-level Wacker Drive; and construction of a new utility tunnel beneath Wacker Drive and the Chicago River.
The project incorporated numerous sustainable elements and practices, including a roughly 95 percent rate of material recycling into new aggregate and iron that was used in new construction. The new thin-slab post-tensioned superstructure will keep the entire deck in compression at all times, precluding tension cracks from occurring and limiting the intrusion of salt and water, thus reducing the need for future repairs and the environmental impacts associated with construction.
Publicly accessible green space and a park were added to the corridor in areas created by the more efficient configuration of ramps and interchanges. LED traffic signals — more energy cost-effective than incandescent bulbs and longer lasting — were used throughout. A stormwater management system designed to direct storm runoff into the combined sewer system instead of the Chicago River was also incorporated into the project, helping to rebalance river flora and fauna.
Wacker Drive’s new infrastructure has created a safer and more efficient transportation facility that benefits commuters and visitors to downtown Chicago. The revitalization has made it easier to navigate Chicago's central business district while relieving congestion. People working and visiting the downtown area can now enjoy parks and green spaces, landscaped medians with planter boxes, and architectural lighting that beautifies Wacker Drive.