The 22 bridges are more than 100 years old and can no longer be economically repaired and maintained. The new bridges will offer increased safety and are expected to last for more than 100 years.

The replacement will be done in two phases of 11 bridges each. The first phase, which will take until 2015, will cover bridges over Balmoral, Foster, Winnemac, Lawrence, Leland, Wilson, Sunnyside, Montrose, Berteau, Irving Park and Grace. The work also includes retaining wall construction along the western edge of the elevated tracks. The bridge and retaining wall work will require periodic closures of streets and sidewalks in the area.

Bridges between Addison and Webster will be done in the second phase, which will finish in 2019.

Construction of the new Ravenswood Station, the only stop in the construction zone and the busiest stop on the UP North line, will also be done during the first phase, starting in Spring 2012. The new station, to be rebuilt in its current location, will offer longer, covered platforms, warming shelters, improved lighting, landscaping, a ticket office, vendor space, ramps and stairs. It will be compliant with the Americans with Disabilities Act.