If you are destined to die in a car crash around here, the odds are almost one in four that you’ll get killed at an intersection, but your chance of avoiding a crash is improving if you live in Arlington County.

Four red light cameras installed there have proven to do what proponents of the cameras have long said they would: save lives. Over time, drivers who regularly pass through an intersection come to know the cameras are there. Wary of a ticket, they keep a sharper eye on the traffic light so they can stop if they expect it to turn red.

Evidence that the cameras, which are in use throughout the region and the nation, are effective in Arlington came to light this week because that’s where the Insurance Institute for Highway Safety is based.

When researchers at the industry-supported facility heard that Arlington was installing cameras at four intersections in 2010, they began working with the county to see how well they worked.

They used cameras to track the cameras, video recording the intersections during an initial 30-day period when drivers just got warnings, then for another month when tickets began being issued, and they came back a year later for a month of taping to see whether red light running had decreased.

For comparison, they also did video recording at four Arlington intersections where no red-light cameras had been installed.

They broke down the results into three categories that might be described as running a slightly red light (less than 0.5 seconds after the light changed to red), running a red light (1 second after) and running a very red light (one that had been red for at least 1.5 seconds). Running a very red light is far more dangerous because there’s a good chance that another car may have entered the intersection by then.

A year after cameras began issuing tickets at the intersections, the researchers determined that running slightly red lights was down by 39 percent, running red lights had dropped by 48 percent and running very red lights was down by 86 percent.

“What these numbers show is that those violations most likely to lead to a crash are reduced the most,” said Anne McCartt, who wrote the institute’s report. “Automated enforcement can get drivers to modify their behavior.”

The results at intersections without ticket cameras were mixed and not considered statistically significant. Red-light running went down at two of them and up at two others. McCartt said that’s likely because too few people knew about the ticket cameras. She said that may change as the county installs more of them.

“We would expect a broader effect to emerge after the program’s expansion to other parts of Arlington,” she said.

Use of red light cameras beyond the confines of Arlington is lowering the road death count throughout the Washington region, according to John B. Townsend II, who monitors such matters for AAA.

“They save lives,” he said. “They are reducing fatalities and the severity of injuries, they are lessening the odds of red light running episodes, and they are modifying the driving behavior of motorists who sometimes tend to push the envelope and take chances at intersections.”

About a quarter of the 2,539 people killed in auto accidents in the Washington region between 2004 and 2010 died in crashes at intersections, according the state and federal data.

Nationally, the institute said, more than 2.2 million crashes in 2010 happened at or near intersections. That accounted for 42 percent of all collisions, 7,707 deaths and more than 68,000 serious injuries. About one-third of those deaths were at intersections with signal lights.

When the institute, which draws data from insurance claims, studied red light programs in large cities two years ago, it determined that enforcement cameras reduced fatalities at intersections with signals by 24 percent, and all types of fatal crashes at signal lights by 17 percent.