Red light cameras saved 159 lives in 2004-08 in 14 of the biggest US cities, a new analysis by the Insurance Institute for Highway Safety shows. Had cameras been operating during that period in all large cities, a total of 815 deaths would have been prevented.

"The cities that have the courage to use red light cameras despite the political backlash are saving lives," says Institute president Adrian Lund.

Looking at the 99 US cities with populations over 200,000, the researchers compared those with red light camera programs to those without. Because they wanted to see how the rate of fatal crashes changed after the introduction of cameras, they compared two periods, 2004-08 and 1992-96. Cities that had cameras during 1992-96 were excluded from the analysis, as were cities that had cameras for only part of the later study period.

The researchers found that in the 14 cities that had cameras during 2004-08, the combined per capita rate of fatal red light running crashes fell 35 percent, compared with 1992-96. The rate also fell in the 48 cities without camera programs in either period, but only by 14 percent.

Based on that comparison, the researchers concluded that the rate of fatal red light running crashes in cities with cameras in 2004-08 was 24 percent lower than it would have been without cameras. That adds up to 74 fewer fatal red light running crashes or, given the average number of fatalities per red light running crash, approximately 83 lives saved.

The actual benefit is even bigger. The rate of all fatal crashes at intersections with signals — not just red light running crashes — fell 14 percent in the camera cities and crept up 2 percent in the noncamera cities. In the camera cities, there were 17 percent fewer fatal crashes per capita at intersections with signals in 2004-08 than would have been expected. That translates into 159 people who are alive because of the automated enforcement programs.

This result shows that red light cameras reduce not only fatal red light running crashes, but other types of fatal intersection crashes as well. One possible reason for this is that red light running fatalities are undercounted due to a lack of witnesses to explain what happened in a crash. Drivers also may be more cautious in general when they know there are cameras around.

Based on these calculations, if red light cameras had been in place for all 5 years in all 99 US cities with populations over 200,000, a total of 815 deaths could have been avoided.

Since the 1990s, communities have used red light cameras as a low-cost way to police intersections. The number of cities embracing the technology has swelled from just 25 in 2000 to about 500 today.

National surveys indicate widespread support for red light cameras. At the same time, opponents of automated enforcement have become increasingly vocal, claiming that camera programs are revenue-generating schemes that violate drivers' privacy.

"Somehow, the people who get tickets because they have broken the law have been cast as the victims," Lund says. "We rarely hear about the real victims — the people who are killed or injured by these lawbreakers."

Red light running killed 676 people and injured an estimated 113,000 in 2009. Nearly two-thirds of the deaths were people other than the red light running drivers — occupants of other vehicles, passengers in the red light runners' vehicles, bicyclists, or pedestrians.

Without cameras, enforcement at intersections is difficult and often dangerous. In order to stop a red light runner, officers usually have to follow the vehicle through the red light, endangering themselves, as well as other motorists and pedestrians.

Moreover, the manpower required to police intersections on a regular basis would make it prohibitively expensive. In contrast, camera programs can pay for themselves by requiring people who break the law to shoulder the cost of enforcing it.

Previous research has established that red light cameras deter would-be violators and reduce crashes at intersections with signals. Institute studies of camera programs have found that red light violations fell at intersections where cameras were installed and that this effect also spilled over to intersections without cameras. An Institute study in Oxnard, Calif., found that injury crashes at intersections with traffic signals fell 29 percent citywide after automated enforcement began.

The new study adds to this by showing that cameras reduce not only violations and crashes throughout entire communities but deaths, too.

"Examining a large group of cities over several years allowed us to take a close look at the most serious crashes, the ones that claim people's lives," says Anne McCartt, Institute senior vice president for research and a co-author of the study. "Our analysis shows that red light cameras are making intersections safer."

Results in each of the 14 camera cities varied. The biggest drop in the rate of fatal red light running crashes came in Chandler, Ariz., where the decline was 79 percent. Two cities, Raleigh, NC, and Bakersfield, Calif., experienced an increase.

"We don't know exactly why the data from Raleigh and Bakersfield didn't line up with what we found elsewhere," McCartt says. "Both cities have expanded geographically over the past two decades, and that probably has a lot to do with it."