Construction began in late 2013, with the project split into 35 separate contracts or project components.
IDOT has taken a unique approach to reconstructing the interchange, utilizing a phased approach that allows IDOT to construct parts of the Interchange while design continues on other components. This phased approach is required to address the various constraints and challenges of the site, which include:
- REBUILD IN THE SAME FOOTPRINT. The larger improved interchange needs to fit in the same area as the existing constrained interchange. Several site constraints present unique challenges that must be taken into consideration including the CTA Blue Line, Cermak pump station, underground water tunnels, and poor soil conditions.
- MAINTAIN 400,000 VEHICLES/DAY. The overall interchange project area maintains 400,000 vehicles daily. Closing completely to speed up construction would be detrimental to a key node of the area’s transportation network. Construction must work around existing traffic to cause the least amount of disruption possible and minimize lane closures.
- ONE EXPRESSWAY AT A TIME. This is not the only ongoing construction project in the city. To minimize traffic impacts from having more than one downtown expressway under construction at the same time, work had to be staggered around the full reconstruction of the interchange between I-55 and Lake Shore Drive.
- UNFORESEEN CONDITIONS. Challenges with unknown conditions below ground have affected the reconstruction. An abandoned brick water tunnel that previously served an elevated rail line has been encountered in numerous construction projects. The remnants of long forgotten Chicago continue to be found within this project.
- WORK RESTRICTIONS. Contract requirements limit how often a contractor is allowed to close lanes or ramps. Major construction does take place at night, however, noise must be considered. Some limitations include many weekends to avoid impacts during holidays, sporting events, festivals and other major events in the city.
- UNIQUE CHALLENGES. The city maintains an active water pumping station on Harrison Street between the southbound and northbound I-90/94 lanes. Abandoned water supply tunnels have been filled to accommodate bridge construction and the existing water supply pipes have required relocation and rehabilitation.