Red light cameras may be controversial, but they save lives, according to a new national study of 62 large U.S. cities, including Sacramento.

The study, released today by the Insurance Institute for Highway Safety, found that the rate of fatal red light crashes has decreased in large cities across the country since the mid-1990s, regardless of whether they had red light cameras or not.

But the biggest drops came in cities that installed red light cameras: 35 percent compared with 14 percent in cities without cameras. Fourteen cities with red light cameras were compared with 48 cities without.

The city of Sacramento, which has red light cameras at eight intersections, saw an even more substantial drop - 53 percent. Its study-period numbers were small, however, a total of 23 fatal crashes caused by red light runners over eight years.

Notably, the insurance institute based its findings on an analysis of all intersections in the study cities, not just intersections with red light cameras. Institute officials said accurate data exclusively from intersections with cameras would have been difficult to obtain.

They defended the decision by saying the different crash rates between cities with cameras and those without is substantial enough to indicate a "halo effect" is in play: Motorists in areas with red light cameras adapt their driving habits in general, becoming safer even at intersections that do not have cameras.

"The benefits extend throughout the city, not just at the intersections with cameras," institute spokesman Russ Rader said.

The institute, funded by member companies including State Farm, Allstate, Nationwide and Progressive, reports the number of cities employing red light cameras jumped from a handful 15 years ago to more than 500 last year.

In the Sacramento region, cameras are used at about three dozen intersections, including eight in the city of Sacramento, nine in Sacramento County, five in Citrus Heights and two in Davis.

Those numbers are expected to increase as early as next month.

Sacramento city and county officials are studying 20 intersections as potential new sites, and could begin installing cameras in March, Lt. Rich Kropp of the Sheriff's Department said. He declined to say where cameras might be added in the unincorporated area, saying the county has not finalized its list.

City officials said they expect to add cameras at as many as 10 more intersections. Up first, they said, are J Street and Alhambra Boulevard, which previously had a set, and at 16th and W streets.

Elk Grove, which boosted general fund revenue a few years ago when it installed video cameras that ticket right-turn red light runners, is considering adding cameras at a fifth intersection this year. Rancho Cordova officials also are studying the possibility of adding cameras.

Not all cities in the region are enthused by the sometimes controversial devices.

Folsom city officials say they have no plans for cameras. The West Sacramento City Council recently turned down a police request to install two red light cameras.

Roseville had four in place, but took them out when changes to those intersections made them ineffective, officials said.

Some red light camera studies have shown that rear-end collisions increase when red light cameras are installed, but insurance institute head Adrian Lund said those crashes are few, and usually far less severe than the intersection broadside crashes that happen with red light running.