Extreme summer heat caused two movable bridges in Chicago to malfunction on Wednesday, trapping them in the raised position and triggering multi-hour traffic jams across the city, according to local officials and transit reports.
Bridge Malfunctions During Chicago Heat Wave
The disruptions began around 10 a.m. on Wednesday when the DuSable Lake Shore Drive Bridge became stuck for more than four hours following a routine lift to allow a yacht to pass. Temperatures at O’Hare International Airport reached 96 degrees Fahrenheit on Wednesday, following a 95-degree day on Tuesday, as reported by the National Weather Service. Chicago Midway International Airport recorded a heat index of 106 degrees on Tuesday.
Crews spent hours working to lower the span while a Chicago Fire Department fireboat sprayed water onto the metal structure to cool it down, as travelers waited along the Lakefront Trail. Later that afternoon at 4:30 p.m., the Torrence Avenue Bridge over the Calumet River on the city’s far South Side stuck in the raised position for more than an hour, creating further vehicle backups and forcing police detours.
“Thermal expansion caused by high temperatures affected the operation of the bridge,” a Chicago Department of Transportation spokesperson said regarding the incidents.
How Thermal Expansion Affects Movable Bridges
The Chicago Fire Department explained in a public statement that extreme heat causes bridge metal to expand, creating jams that prevent the spans from opening or closing properly. Jim Phillips, founder of ChicagoLoopBridges.com, noted that bascule bridges like the DuSable Lake Shore Drive span are normally shielded somewhat from thermal expansion by cooler air rising from the river underneath them while closed.
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“Once lifted, the bridge deck is exposed to higher temperatures and expands,” Phillips said, adding that the expansion is occasionally enough to disrupt the mechanism when trying to return the platform to its closed position. While bridge jams caused by heat are uncommon, historical records show similar incidents, such as a 2010 event where workers hosed down the State Street Bridge when temperatures exceeded 85 degrees.
Vulnerability of Aging Urban Infrastructure
Chicago operates more movable bridges than any other city in the United States, leaving its transit network potentially vulnerable to extreme weather, according to Grace Truslow, a policy analyst at the Washington D.C.-based Eno Center for Transportation. Joseph Schwieterman, director of the Sustainable Urban Development Program at DePaul University, noted that aging bridges frequently suffer from minor misalignments due to wear and tear, slight shifts in supporting piers, and small deformations that elevate the risk of improper closing.
An analysis of federal bridge inspection records by the Chicago Sun-Times indicates that 17% of Chicago bridges are classified as structurally deficient. Exactly 100 of the 601 Chicago bridges are in a “poor” condition, which is 16.6%, and stands well above the national average of 6.7%.
Mitigation and Wider Transportation Impacts
Despite the operational challenges posed by high temperatures, city officials cannot easily halt bridge lifts during the summer. Schwieterman pointed out that the Chicago River functions as a federally designated navigable waterway utilized constantly by sailboats and other vessels, making full suspensions of bridge openings unrealistic.
Truslow suggested that transportation agencies can mitigate heat-related risks by deploying sensors and conducting preventive inspections when temperatures cross specific thresholds, allowing operators to make targeted adjustments or time lifts away from peak heat hours. Beyond Chicago, the ongoing summer heat wave has warped infrastructure, causing pavement buckling on U.S. 69 in Greenville, Texas and tire blowouts on Interstate 49 in Louisiana, according to Eno Center data.
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