They also noted that the city chose to install many cameras at intersections where crashes were rare to begin with. Chicago has raised roughly $500 million from red light camera tickets since 2002. "[O]fficials recently admitted to the city inspector general that they had quietly dropped the threshold for what constitutes a red light camera ticket, allowing the tickets even when cameras showed a yellow light time just under the three-second federal minimum standard. That shift earlier this year snared 77,000 more drivers and $7.7 million in ticket revenue before the city agreed to change the threshold back.
In 2013, the researchers studied the emissions of more than 68,000 vehicles on the roads in three cities—Los Angeles, Denver, and Tulsa. They calculated the amount of pollution released per kilogram of fuel burned for the 2013 fleet and compared the rates to those that would have occurred if the 2013 fleet had the same age distribution as the prerecession fleet. For the three cities, carbon monoxide emissions were greater by 17 to 29%, hydrocarbons by 9 to 14%, nitrogen oxide emissions by 27 to 30%, and ammonia by 7 to 16%.