Why is a Highway 45 overpass dropping chunks of concrete?

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MILWAUKEE (WITI) -- Pieces of concrete fell from a bridge just north of the Zoo Interchange on Saturday afternoon, May 10th -- but the Wisconsin DOT says bridges in the Milwaukee area are safe.

The debris fell on Saturday on two of the northbound lanes of Highway 45 at Bluemound Road.

The Wisconsin DOT says the overpass at Highway 45 is structurally sound, but says it has found concrete with the potential to break away.

Mike Pyritz with the DOT says chunks of concrete broke off of the overpass and struck at least two cars.

Several northbound lanes were closed, while the DOT looked for other problem areas.

A crew was back on Monday morning, May 12th -- removing other chunks of loose concrete.

So why is the bridge dropping chunks of concrete?

"There are a number of factors certainly. The harsh winter the age of the structure itself certainly contributed to what occured," Pyritz said.

The particular overpass that dropped the concrete this weekend was built in 1961 -- making it more than 50 years old.

The DOT says there are many bridges just like this one throughout southeastern Wisconsin.

The DOT currently has more than a dozen projects happening right now -- addressing an aging infrastructure.

"We've got studies going for the East -West cooridor, up on 43, work here on 45. We are certainly working on a very broad swath," Pyritz said.

As for the bridge on 45, it is part of the Zoo Interchange project and is scheduled to be replaced in October.

Pyritz and the DOT says crews will continue to monitor bridges and overpasses throughout southeastern Wisconsin looking for issues and addressing them.

No injuries were reported when the concrete chunks came crashing down on Saturday.