CONTENT EXPIRES: December 31, 2027 

The Red and Purple Modernization (RPM) Phase One Project is the largest capital improvement project in Chicago Transit Authority (CTA) history. The scope is to replace, reconstruct, and modernize ~10 miles of elevated track and support structures along Chicago's busiest transit corridor to increase train speeds and add capacity to CTA’s system with new structures designed for a 100-year service life. Design and construction features of this project include multiple alternative technical concepts (ATCs); CTA transit operations maintained throughout all phases of construction; advanced analyses including rail-structure interaction and vehicular-structure interaction; relocation of a historic building; and noise studies/abatement for community integration in design. ATCs allowed for the use of precast prestressed concrete (PPC) beams and the use of precast segmental box girders, which lowers cost, shortens construction schedule, reduces foundations, and minimizes maintenance. Design refinement with the contractor resulted in an optimized design for complex construction elements and use of the ATCs to minimize community impacts. The complex nature of this project in a dense urban environment resulted in staging the work to maintain transit service for the community while working to deliver a more reliable and enjoyable transit experience for Chicago commuters.