A study in Virginia has found that red light cameras don't actually reduce the number of injury accidents but instead actually increase the number.

Despite a distinct sympathy in favor of camera enforcement, the researchers found a "definite" increase in rear-end accidents and only a "possible" decrease in angle accidents. Most importantly, the net effect was that more injuries happened after cameras are installed. Camera proponents explain this away by asserting angle accidents are more serious, but this claim has not been scientifically studied according to this report. The rear end collisions caused by the cameras still produce injuries -- the original promise of camera proponents was that they would reduce accidents and injuries, not rearrange them.

--theNewspaper.com