CHICAGO (CBS) — Canadian National Railway will add additional support to a Michigan Avenue bridge after a piece of metal fell off the overpass on Monday.

After an inspection, engineers found that the bridge is still safe, but CN will add support to a drainage structure “out of an abundance of caution,” according to a statement.

“The material [that fell] was a non-structural component and was a part of an obsolete drainage structure,” the CN statement said.

Thousands of drivers pass under the railroad bridge over Michigan Avenue at 16th Street daily. People are able to walk underneath too. When a huge piece of metal fell from the bridge Monday morning, it didn’t injure anyone.

But there was concern that it would happen again. It is a growing concern at the site steps away from Old St. Mary’s School, especially for parent Chely Frantzen.

“The piece that fell, fell from right here,” Frantzen said as she pointed to a support column.

The huge metal piece crashed from right above the roadway.

“Cars had to swerve around it,” Frantzen said. “It was about five feet long. It looked like a white piece of metal.”

The drainage structure “is unique to Michigan Avenue because of its architectural detail …  It is not found on the other bridges in the area,” CN said.