One person was injured when concrete fell from Upper Lake Shore Drive onto Lower Lake Shore Drive.
It happened just north of the Chicago River on the pedestrian path near Illinois.
The person injured was on the sidewalk where most of the concrete fell. Some also fell onto the roadway. The extent of the injuries is unknown at this time.
Chicago Dept of Transportation inspection crew have been on the scene since the incident happened around noon.
The sidewalk was closed temporarily while crews cleaned up.
They are no working on the street and have closed one lane of traffic, according to CDOT.
CDOT says the bridge is structurally sound and the concrete came loose after several decades of weather and wear and tear.