The study by the Insurance Institute for Highway Safety said the cameras have reduced the rate of fatal crashes by 24 percent in the 14 large cities that began using them between 1996 and 2004.
But some disagree with the findings. The National Motorists Association claims the cameras increase rear-end collisions and that more effective options are available.
Crashes went down in some Southern California cities that have the lights installed.
In Long Beach, the number of fatal red-light-running crashes went down 34 percent from 14 to 10 in the time period studied.
In Santa Ana, the number of fatal crashes dropped by 44 percent.