The Monday morning rush on the Edens Expressway turned into a slow-motion crawl on May 4, 2026, after a semi-truck leaking a corrosive chemical pulled over between Morton Grove and Skokie. The truck stopped just past the westbound entrance at Dempster Avenue, and emergency crews quickly shut the ramp to northbound I-94 while hazmat teams moved in to contain the spill. With lanes blocked and inbound drivers slowing to gawk, commuters in both directions were stuck in heavy backups.
What Spilled and How Crews Contained It
Illinois State Police identified the truck's cargo as sodium bisulfate, a corrosive, acidic salt commonly used to lower pH in pools and industrial water systems, and said the trailer appeared to be leaking from the rear, according to CBS Chicago. By about 6:45 a.m., skywatch video and on-scene reporting showed fire crews and hazmat teams on the ground, dumping sand under the trailer and building makeshift dikes to keep the material from spreading.
Traffic Mess and What Drivers Faced
The Dempster entrance to northbound I-94 was closed and the right lane of the outbound Edens was blocked, Illinois State Police said in an update relayed by Patch. That setup left drivers between Morton Grove and Skokie grinding through long delays, while inbound traffic also bogged down as motorists hit the brakes to look over at the hazmat scene.
Why Sodium Bisulfate Is a Big Deal
Sodium bisulfate (NaHSO4) is classified as corrosive and can cause eye and skin damage and respiratory irritation if inhaled, and it is corrosive to metals, according to chemical safety guidance. National chemical databases and safety data sheets say responders should wear full protective gear and use absorbent materials when handling spills, and that cleanup typically requires hazmat teams and proper disposal of anything contaminated, per PubChem.
Cleanup Timeline and What Comes Next
Officials at the scene had no immediate estimate for when the Dempster ramp would reopen, Illinois State Police told CBS Chicago. Drivers were urged to steer clear of the stretch or build in extra travel time while hazmat crews finished containment and the blocked lane was cleared.
