Study: Speed cameras reduce traffic crashes

David Shepardson
Detroit News Washington Bureau

A new study released Tuesday shows speed cameras have prompted long-term changes in driver behavior and led to substantial reductions in deaths and injuries.

The Insurance Institute for Highway Safety says a study of speed cameras first introduced in Montgomery County, Maryland — just outside Washington, D.C. — in 2007 shows a big decline in crashes and changes in driver behavior.

The program reduces fatal or incapacitating injuries by 39 percent on residential roads with speed limits of 25-35 mph, the researchers found.

As of 2014, the county had 56 fixed cameras, 30 portable cameras and six mobile speed vans. The cameras are used on residential streets with speed limits of 35 mph or less and in school zones.

IIHS originally looked at the Montgomery County program during its first year. Six months into the program, the proportion of drivers traveling at least 10 miles over the speed limit had fallen on streets with cameras.

Seven years later, the program is still working. Cameras have reduced by 59 percent the likelihood of a driver exceeding the speed limit by more than 10 mph, compared with similar roads in two nearby Virginia counties that don’t have speed cameras, the latest study found.

“We hope this research will help energize the discussion around speed,” said IIHS President Adrian Lund, who will unveil the findings Tuesday at the annual meeting of the Governors Highway Safety Association in Nashville. “We’re all accustomed to seeing posted limits ignored, but it’s a mistake to think nothing can be done about it. Automated enforcement is one of the tools we have at our disposal.”

Automated speed enforcement is still rare but gradually becoming more common around the country. IIHS — the industry-funded group that works to reduce auto crashes — says just 138 jurisdictions operate such programs. If all U.S. communities had speed-camera programs like the one IIHS studied in Maryland’s Montgomery County, the goupl estimates more than 21,000 fatal or incapacitating injuries would have been prevented in 2013.

The study compared crashes on camera-eligible roads in Montgomery County to comparable roads in Virginia. They found that the camera program resulted in a 19 percent reduction in the likelihood that a crash would involve a fatality or an incapacitating injury.

“Speed cameras get drivers to ease off the accelerator, and crashes are less likely to be deadly at lower speeds,” Lund said. “This study connects the dots to show that speed cameras save lives.”

In 2012, Montgomery County introduced speed-camera corridors. With corridors, enforcement is focused on long segments of roads instead of specific locations. The cameras are regularly moved to different locations on those roads so drivers don’t become familiar with their exact locations.

The study said corridor approach led to further gains, reducing the likelihood of a crash involving fatal or incapacitating injury an additional 30 percent beyond the use of cameras alone.

“Speed-camera corridors force drivers to watch their speed for the length of the road, instead of slamming on the brakes at a specific location and then speeding up again,” said Anne McCartt, the Institute’s senior vice president for research and a co-author of the study.

The total benefit would likely be even greater because that number doesn’t include any spillover effect. Drivers in Montgomery County seem to have slowed down even on roads that aren’t eligible for automated enforcement. The researchers found that fatal or incapacitating injuries fell 27 percent on 40 mph roads as a result of the camera program on roads with limits of 35 mph or less.

IIHS notes that cameras succeed in changing behavior only if drivers know about them. In Montgomery County, 95 percent of drivers surveyed were aware of them. More than three-quarters said they had reduced their speed because of the program, and 59 percent had received a speed-camera ticket personally.

The group noted that automated enforcement has been criticized, and some communities have eliminated programs because of a backlash.

AAA said Washington, D.C., raised $85 million in ticket revenue in 2011, including $72 million from speed cameras and $13 million in red-light tickets. AAA says it “strongly supports traffic safety measures designed to reduce red light running, including increased enforcement and traffic-engineering improvements. The installation of red light cameras is acceptable when these counter-measures are not successful. However, the sole purpose of red light cameras must be increased safety, not increased revenue.”

Jonathan Adkins, Executive Director, Governors Highway Safety Association, said, “This study demonstrates that automated enforcement can be an effective deterrent to an speeding, which continues to contribute to about one-third of all traffic fatalities nationally. The Maryland program is a model for other communities looking to address this often overlooked, yet pervasive dangerous driving behavior.”

Since 2013, the Michigan legislature has considered several proposals to allow counties and cities to use speed and red-light cameras. Michigan does not currently used them because then-state Attorney General Mike Cox issued an opinion in February 2007 declaring that red-light cameras are illegal under state law. That scuttled a plan by Southgate to install the cameras.