Chicago Transit Authority (CTA) in the US, along with local authorities, is planning to invest $1bn to eliminate slow zones, repair tracks, improve stations on Red Lines and improve the Purple Lines.
The project involves replacing tracks between 18th Street and 95th Street, as well as improvement of stations between Cermak and 95th Street.
The scope of work also involves the rebuilding of the Wilson and Clark / Division stations and the surrounding track, the underground portion of the Red Line through downtown Chicago, and three electrical substations.
The Red Line extends 23 miles between the Howard and 95th Street stations.
The project will also replace ties on the Purple Line track between the Belmont and Linden stations, and eliminate slow zones on 24% of the express service, which limits the speed of trains to 35mph or less.
The construction of the project is expected to start by next year and will last three years.
About $646m of funding will come from capital programme, $255m will come from the US Government, and about $44m will be contributed by Chicago city.