That simple question has four answers: Yes, No, Maybe, and It Depends. But it takes a lot of research, a lot of reading, and a lot of money to come to any of these conclusions.
After looking at more than ten studies on both sides of the red light camera argument, the general trends stand up quickly. What is behind them are lots of asterisks and disclaimers, however, such that every one of those four answers is qualified.
Yes, Red Light Cameras Reduce Accidents
The idea that red light cameras reduce accidents is generally true if you are referring to broadside (or "T-bone") accidents. This is the worst kind of collision you can have at an intersection, when a car enters crossing traffic and plows into the side of another car. A slightly greater number of studies showed that these broadside incidents were reduced by red light cameras. A November 2008 study carried out by the Center for Transportation Safety of the Texas Transportation Institute at Texas A&M University found "a 43 percent annualized decrease in right angle collisions" at 56 intersections with red light cameras. A 2007 study by Iowa State's Center for Transportation Research and Education concluded that the "expected average number of crashes per quarter for [red-light-running]-related crashes (non-rear-end) decreased by 40 percent after installation of cameras at intersections with camera-enforced approaches."
The same results were discovered in studies for the Transportation Research Board in 2003 ("angle crashes are usually reduced"), a 2007 study for the Virginia Transportation Research Council ("a decrease in red light running crashes, about 8 percent or 42 percent depending on the statistical method used"), and a 2004 study by the Urban Transport Institute ("one type of accident found to experience a decrease at [red light camera] sites are those involving a left turning car and a car traveling on a different roadway").
But as we suggested before, even those yeses are called into question by other studies. The Washington Post conducted a review of traffic accident data at 45 red light camera intersections during 1999 and 2000, finding that "Broadside crashes, also known as right-angle or T-bone collisions, rose 30 percent, from 81 to 106 during that time frame."
No, Red Light Cameras Don't
Although there are no easy answers, when it comes to argument against red light cameras, the preponderance of evidence is much clearer. While cameras are often credited for reducing broadside accidents, and sometime reducing accidents between cross traffic and those making a right turn on red, they are almost universally credited for increasing rear-end accidents. You have to rummage through a lot of paperwork to find studies, like the one from Iowa State, that claim reductions in rear-end crashes at monitored intersections.
Even the government's look into the matter found that rear-end crashes go up at intersections with the cameras: A 2005 study by the Federal Highway Administration found an average increase of 15 percent in rear-end crashes after looking at 132 locations in seven areas. In the journal of the Institute of Transport Engineers, the group that studies and develops intersection standards, an article that looked at a vast number of studies trying to determine the effects of red light cameras found in almost every case that rear-end crashes increase.
Maybe They Do, Maybe They Don't
Then there is the issue of injuries. While one type of accident said to...