Northbound lanes of Lake Shore Drive were closed Monday between Randolph Street and Grand Avenue for a "structural emergency" on the bridge, officials said.
The section was closed for repairs, according to the Chicago Department of Transportation, which said the closure would remain in place through Monday's evening commute and possibly longer.
A crack in a steel beam that supports the roadway was discovered by a CDOT crew in the area, according to officials. No injuries or damage to vehicles had been reported as of Monday afternoon, CDOT said.
Crews were working to "install a shoring tower as quickly as possible under the viaduct structure that carries northbound Lake Shore Drive," Ald. Brendan Reilly said in an email to residents.
Northbound Lanes of Lake Shore Drive to Remain Closed
Chicago Police said northbound traffic was being diverted at Randolph as the bridge was being surveyed. The ramp from eastbound Randolph to norhtbound LSD was also closed.
Access to northbound Lake Shore Drive was available from Lower Wacker Drive and the entrance ramp at Grand Avenue.
Drivers were being urged to instead use Interstate 55 to I-90/94 as an alternate northbound route. Southbound traffic was not being affected, authorities said.