CHICAGO (WLS) -- The largest reconstruction project in CTA's history got underway Wednesday.
Mayor Lori Lightfoot, Senator Dick Durbin and others broke ground for the first phase of major upgrades to the CTA's Red and Purple lines.
"Chicagoans deserve a transit system that is dependable, accessible, and affordable," Lightfoot said.
The $2.1 billion project will be paid for through a combination of federal funds and tax increment financing.
"Our delegation worked together on a bipartisan basis to bring these federal dollars home not just to make sure we have a safe transit system, but to also create real jobs in Chicago," Senator Durbin said.
WATCH: Mayor Lightfoot speaks at groundbreaking for Red, Purple Modernization Project
For the first part of the project, crews will dig holes to make way for new track foundations for the Red Purple Line bypass, designed to help with a bottle-neck where the Red, Purple and Brown lines intersect. The bypass will replace a more than 100-year-old rail that carries thousands of riders each weekday.
"That was a 9.6 mile stretch of track which was built close to a century ago," Lightfoot said. "To put that in perspective, Calvin Coolidge was president."
Those tracks will carry northbound brown line trains over the Red and Purple line tracks north of the Belmont station.
The multi-phase project that will take at least five years to complete comes as the Red Line has reached its capacity with the current infrastructure unable to add train service during the weekday rush.
"Once the work gets done the benefits to the community are tenfold," said CTA President Dorval Carter Jr.
The CTA will also rebuild track structure and four rail stations: Lawrence, Argyle, Berwyn and Bryn Mawr as well as install a new signal system on 23 miles of track between Howard and Belmont.
The new construction will increase train speeds by 60 percent and allow for a smoother and safer ride. Red and Purple line service is expected to continue through construction.
"It is going to be noisy and dirty and we are doing everything we can to mitigate those impacts," Carter said.