Threading the needle: Upgrading the “L” in the heart of urban Chicago

Cities like Chicago grow around their historic transit systems. New updates need to be threaded through the city and around homes, businesses, and existing infrastructure.

So how do you upgrade an elevated rail line that runs within inches of homes and businesses? What’s required when you must move a historic building to straighten the track? And how do you phase the construction so you can maintain essential transit service for people who rely on it?

The $2.1 billion Red and Purple Modernization program is the largest capital project in Chicago transit history and one of the most significant transit projects in the United States. This video explores how the project came to be, and how engineering and construction solutions made it possible.