Chicago Bridge Faces Corrosion Issues
Permanent repairs on Chicago’s Lake Shore Drive Bridge are underway roughly almost three weeks after a crack in one of the bridge’s steel beams was first discovered by a crew working in the area. The damage has largely been attributed to corrosion made worse by extreme weather, according to reports.
According to the Chicago Tribune, the 33-year-old bridge, which is not ranked among the area’s worst bridges in terms of condition, was shut down Feb. 11 to allow for repairs.
Lake Shore Drive Bridge Issues
Rebekah Scheinfeld, commissioner of the Chicago Department of Transportation, noted that the cracks were first spotted by a crew working on traffic signal repairs the morning of Feb. 11. An engineering crew arrived and made the call to shut down the roadway. The damage to the bridge has largely been attributed to corrosion exacerbated by the extreme weather.
Scheinfeld told the Tribune that seven steel girders run along the roadway at that point, under the viaduct near expansion joints. Two of the seven girders reportedly had cracks. At the time, the city planned to install steel plates beneath the roadway as a permanent fix.
A northbound Lake Shore Drive bridge, closed as a result of cracked steel beams, reopened this afternoon. But the damage raises questions about the reliability of other area bridges, especially as extreme weather creates more stress on materials. https://t.co/gh8UpscLcE— Chicago Tribune (@chicagotribune) February 13, 2019
According to the Tribune, the impacted section, which was built in 1986, is south of the steel bascule double-decker bridge, constructed in 1937. That bridge, which has a main span length of 264 feet, and a total structure length of 356 feet, is one of the most heavily traveled structurally deficient bridges in the state.
The bridge is inspected once every two years, with the last inspection occurring in June 2017 and the next slated for June of this year. The bridge was closed for repairs for 26 hours as a result of the damage.
As a temporary fix, the city set up several steel support towers to brace the structure. P.S. Sriraj, director of the urban transportation center at University of Illinois at Chicago, noted that the issue demonstrated the need to investing in infrastructure both across the state and across the nation.
“What needs to be taken into account is that Illinois has the third-largest number of bridges, and a significant amount is structurally deficient—16 percent,” Sriraj said, going on to add that the state had only invested $2.6 billion in funding for bridge improvement over the past six years, when the need is $10 billion.
Sriraj also noted that the damage was likely associated with the structure’s age, and Scheinfeld said that the issue was “unexpected.”
According to CBS Chicago, as of earlier this month, custom fabricated steel plates were being installed to hold the bridge together. With the support beams in place to brace the bridge, the Chicago Department of Transportation has been working on preventative maintenance and repairs, including cleaning and painting sections of the steel in preparation for installing the plates.
“Right now the load is carried by those towers, so once they remove the towers, the load will transfer from the girder to the expansion joint. And they can make sure that all the stresses are below the limit. And so we can safely use that new retrofitted connection,” said Didem Ozevin, a civil engineer at UIC College of Engineering.