UPDATED: 9/4/2013 6:00 p.m.

CHICAGO (CBS) — A Lake Shore Drive overpass that was closed after a chunk of concrete fell off it on Tuesday has been deemed “safe” by the city.

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WBBM Newsradio’s Nancy Harty reports ramps to and from Lake Shore Drive at LaSalle Drive, near North Avenue, were closed for four hours Tuesday evening, after a 30-square-foot chunk of concrete fell from the overpass.

Department of Transportation spokesman Peter Scales said crews removed any remaining loose concrete, and checked to make sure the overpass was safe before reopening the roadways around 8:45 p.m. Tuesday.

Scales said the overpass was rated in “fair condition” during its last inspection in December 2012. It was built in 1930 and crews repaired it five years ago.

A combination of age, water damage and traffic vibration is what CDOT says caused a massive slab to fall from the side of the bridge onto LaSalle Drive.

The same thing happened at the Lake Shore Drive overpass and Grand Avenue in May.

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The crumbling concrete does not pose a threat to the bridge itself.

But an Illinois Institute of Technology professor noticed some more problems with the LaSalle Drive location on Wednesday, CBS 2’s Chris Martinez reports.

“This is even worse,” said G.K Fu, noting steel supports of some bridge beams were rusted and exposed.

The professor found steel supports of some bridge beams rusted, exposed – unprotected, which he says could pose a problem for the bridge.

“If the beams come down, you don’t have a bridge,” said Fu. “We go home and sleep, this process is still continuing getting worse and worse and worse, that’s the concern.”

That bridge saw it’s last major repair about five years ago and it passed its last inspection.

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CDOT plans more inspections this week.