Modernizing Chicago’s Train Tracks for Today’s Demands

DYWIDAG helped construct a bypass to improve rail traffic as part of a major program to modernize Chicago’s 120+ year old train system.


With thousands of riders every hour, Chicago’s public transportation system must remain reliable and efficient. In spring 2018, the Chicago Transit Authority (CTA) embarked on a large, multi-phase modernization program to update the 120+ year old rail system. The first phase included constructing a bypass north of the Belmont Station to replace a four-track flat rail section. The outdated track configuration caused significant bottlenecks as northbound Brown Line trains crossed over the four tracks used by southbound Red and Purple Line trains.


The Red-Purple bypass was designed to improve train operations and efficiency. It allows northbound Brown Line trains to proceed on a dedicated rail line above the existing Red and Purple Line tracks. This improvement alleviates congestion and allows the CTA to run up to eight more trains on the Red Line track per hour, meeting the demand for transit service and reducing overcrowding. The new Red-Purple bypass also:

  • Accommodates up to 7,200 additional customers per hour during rush hours

  • Increases Red and Purple Line train speeds by 60 percent through this intersection

  • Saves customers half a million travel hours each year

DYWIDAG supplied post-tensioning materials, including our, tie down bars and couplers for segment lifting, as well as grade 150 High-Strength THREADBAR (GR150) to temporary support brackets.

The overpass was completed in January 2022. The North Main Line construction is expected to be complete in 2024.


City of Chicago