Like many other cities, Chicago uses red-light cameras to ensure traffic safety and to generate revenue from tickets issued to people who drive through red lights.
A recent investigation revealed the city of Chicago made a small but significant change to the time a yellow light changes to red. The Federal Department of Transportation recommends yellow lights of 3 to 6 full seconds in duration. Chicago's yellow lights are 2.9 seconds in duration. Chicago's short yellow lights resulted in more than 77,000 tickets and generated nearly 8M for the city.
Three days after the Chicago Tribune questioned city officials about the short yellow lights, the city suspended the practice on Sept. 22. Weeks later, city officials said they would end the practice–but they would keep the money.