EVANSTON, Ill. (CBS) — CBS 2 got a behind-the-scenes look at a multibillion-dollar project underway to rebuild much of the CTA Red and Purple lines.

It is the largest capital improvement project in Chicago Transit Authority history, and some taxpayers tell CBS 2’s Tim McNicholas the work is badly needed — and fast.

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At Davis Street and Benson Avenue in Evanston, two things are wearing thin – the concrete under the Purple Line and Sharon Lieberman’s patience for a fix.

“I walk under this viaduct many times a week, and it always strikes me that it may fall down, or pieces of concrete may fall down,” Lieberman said.

The Chicago Transit Authority said the 110-year-old bridge in Evanston is safe, but they agree with Lieberman and other taxpayers that an upgrade is due.

When we asked the CTA about the viaduct, we learned they plan to rebuild it as part of a major overhaul of nine and a half miles of the Red and Purple lines.

CTA spokeswoman Tammy Chase took us past the barricades in Edgewater to show us the progress on phase one of that plan.

“We are putting in new, giant pre-cast concrete segments,” Chase said.

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South and northbound trains currently share a track in the Edgewater-Uptown area as crews work on the multibillion-dollar project. The plan is to eventually rebuild 9.5 miles of the Red and Purple lines – including that decaying viaduct in Evanston.

“It’s our intention to rebuild the entire Purple Line in Evanston,” Chase said. “It will be a future phase of the Red-Purple Modernization.”

But the CTA doesn’t know yet when that phase will start or how it will be funded. So far, only phase one is funded — which is scheduled to be done in 2025.

“The Infrastructure Bill that was signed by President Biden, for example, is helpful to, you know, projects that are going on around Chicago and the country,” Chase said.

As to the prospects of when the work would be finished, Lieberman said, “Well, I hope I’m still alive.”

The CTA said they will continue their maintenance of this viaduct and other old bridges.

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“It’s unfortunate, because I think even in three or four years, it’s got to deteriorate even further,” said Lieberman.

Tim McNicholas