CHICAGO (CBS) — Call it carmageddon, or whatever you want, but one thing is certain: the Kennedy Expressway will be a nightmare for motorists driving near to and from downtown this weekend.

Several inbound lanes will being shut down between 10 p.m. Friday and 5 a.m. Monday, as part of a project to demolish a 55-year-old bridge over the Kennedy.

The Ohio/Ontario interchange bridge has been deemed structurally deficient and must come down.

To accomplish that, starting at 10 p.m. Friday, the inbound Kennedy will be reduced to two lanes, beginning a mile before the Ohio Street feeder ramp, so crews can remove a bridge that’s older than the expressway itself. The reversible express lanes will be closed near the Ohio ramp as well.

Taking the bridge down will not be an easy task.

“It was cast as one structure; the three units of one structure. And because of the way that it was constructed, you can’t go in there and take it out piece-by-piece. It’s going to have to be demolished, which is going to bring the bridge down onto the expressway, essentially,” Illinois Transportation Secretary Ann Schneider said.

The first phase of the demolition should be completed by 5 a.m. Monday, so officials do not expect the morning rush to be affected. If contractors do not complete the work by then, they would face a fine for every 15 minutes they are behind schedule.

Even so, the Kennedy will be a traffic nightmare over the weekend, with a number of festivals taking place in or near downtown, including Blues Fest in Grant Park, Taste of Randolph in the West Loop, and the Wells Street Art Festival in Old Town.

A week from Friday, for the second phase of the bridge demolition, the outbound Kennedy will be reduced to two lanes, starting at Congress Parkway. The westbound Ontario ramp to the reversible expressways also will be closed.

During the third and final phase of the project, Kennedy lanes will stay open, but the Ohio Street exit and entrance ramps will be closed.

Work started last August on two new bridges to replace the old one that’s coming down. The entire $18 million project should be completed by October.

Each day, more than 250,000 vehicles use the Kennedy Expressway, so officials were urging drivers to use public transportation at all possible. In an effort to accommodate people who normally take the Kennedy on weekends, the CTA was adding extra bus and train service each weekend of the project. Metra also will have extra cars on some of its trains on the weekends of the demolition project.

If public transportation is not an option, drivers should avoid the Kennedy by taking alternate routes to downtown, such as Lake Shore Drive, the Eisenhower Expressway, or the Stevenson Expressway. For drivers who want to avoid the downtown area altogether, they can take the Tri-State Tollway or I-355 for a north-south route.

Motorists who need to get closer to areas serviced by the Kennedy should try Grand, Milwaukee, and Clybourn avenues as alternate routes, CBS 2 traffic reporter Derrick Young says.

And, of course, tune in to WBBM Newsradio 780 and 105.9FM on for the latest traffic updates on the 8s.

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