Lake Shore Drive Bridge Closed Due To Cracked Beam Could Reopen Before Tuesday Evening Rush

CHICAGO (CBS) -- A massive crack in a beam that holds up a Lake Shore Drive Bridge over the Chicago River will not be repaired until Tuesday night at the earliest, city officials say.

The Chicago Department of Transportation shut down the northbound lanes of Lake Shore Drive between Monroe and Grand, an area thousands use every day.

That closure has since been shifted. Instead of being closed at Jackson, northbound Lake Shore Drive is now closed at Randolph. The Monroe Street intersection is open. Traffic will be able to use the Randolph/Wacker exit to access Randolph and Wacker and also access northbound Lake Shore Drive using Lower Lake Shore Drive over the river.

Eastbound Randolph will remain closed between Columbus and Lake Shore Drive.

It's not clear exactly what caused this or exactly what's in place to make sure it doesn't happen again.

CBS 2 noticed another cracked beam right behind the beam in question. Both are cracks northbound drivers didn't notice Monday morning. No injuries or damage were reported as a result.

The only reason the bridge closed hours later, around 11 a.m., was that a city crew fixing streetlights saw the crack and called it in.

"It's very dangerous," said Dr. Gongkang Fu, department chair of civil engineering at the Illinois Institute of Technology.

CBS 2 took photos, videos and information from the city to Fu, an expert who wrote the book on bridges -- Bridge Design and Evaluation.

"This issue may exist in other spaces, in other beams as well," he said.

Drivers got lucky Monday.

"That needs to be check this time because we've seen this one already failed," Fu said.

One in five of Illinois bridges are deemed structurally deficient.

"Illinois' situation is, I believe, below average," Fu said.

And while this bridge passed its latest inspection in 2017, a state document shows problems including cracks and minor deterioration were reported even then. That damage is almost two years old now. And the recent extreme cold wasn't doing it any favors.

"A small crack can be so small our eyes won't even be able to tell," Fu said.

He said it only takes a few days "for it to fracture to this big."

The bridge would not have been up for another inspection until June.

Currently no one is addressing what is being done to make sure this doesn't happen again.

Crews are working to install a shoring tower. That will allow those northbound lanes to open up. Permanent fixes will then be made around the traffic.

CDOT plans to work through the night to try to get those northbound lanes back open for Tuesday's evening rush, but they say they will only reopen when it's safe.