This $93 million project was designed to alleviate traffic challenges including vehicular congestion and rail flow by eliminating an at-grade crossing of the existing Metra Rock Island District (RID) Line and Norfolk Southern (NS) Line at I-90/94. By raising the RID 29 feet on a new structure in order to fly over the existing NS alignment, the innovative design significantly improved safety for the traveling public. This ambitious project also expanded the RID line from two tracks to a three-track line, and expanded the NS from a three-track line to a four track line with two additional tracks as part of the Midwest High Speed Rail Initiative.
Benesch managed the construction phase of this new 10-span flyover and PPC deck beam approach bridges. The start of the flyover crosses the Dan Ryan Expressway, with the CTA Red Line located in the expressway’s median. Extensive coordination between IDOT and the CTA allowed limited closures during the hours of midnight and 5:00a.m. With challenges such as the Dan Ryan’s narrow median, tall and slender piers had to be used. This allowed for the incorporation of a rare, but innovative technique that used a continuous steel girder bridge. This allowed the entire three-span bridge to be erected with a single fixed end, saving both time and money. Other scope items included the removal of existing steel spans and constructing new abutment piers and retaining walls founded on drilled shaft foundations.
In addition to the extensive infrastructure coordination, the surrounding neighborhoods also required comprehensive coordination. During the project’s construction, Benesch met with the local Homeowners Association to discuss project impacts. Residents were concerned about construction vibration damaging their homes, rodents flushed from the ROW during clearing and grubbing, and traffic flow. Benesch was able to inform residents of the vibration monitoring program and provide contacts to the contractor for preconstruction home inspections. Metra arranged for their rodent control contractor to visit the site and provide rodent control measures. Benesch also provided Traffic Management Advisors (TMA) to keep traffic from cutting through the neighborhood. The project also required individual meetings with local aldermen to address community concerns. In response, Benesch expanded paving limits to incorporate more improvements for each neighborhood and the public in general, as well as some scope extension to address failing infrastructure that was only tangentially connected to the project, but improved the surrounding communities.