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Traffic camera data gives complex picture
Police, Californian analysis tell different tales of collision rates
| Saturday, Feb 9 2008 9:35 PM
Last Updated: Saturday, Feb 9 2008 10:21 PM
Do red-light cameras save lives?
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It's complicated.
Bakersfield Police Lt. Gary Moore says yes. He looked at before-and-after accident rates for intersections with red-light cameras and found that rear-end accidents increased, while the more dangerous broadside accidents declined.
"The broadsiders are the ones that really hurt people," he said.
But a Californian analysis found a muddier picture.
We found that on the whole, accidents actually increased where there are cameras and decreased where there aren't. But that's looking at two big groups of intersections around the city.
A close look at two intersections on Coffee Road -- one with a camera, one without -- seems to back up Moore's point. There, broadsides declined where there is a camera, and rear-enders declined where there's no camera.
RED-LIGHT CITY
Bakersfield's first two red-light cameras were turned on at the beginning of 2003. Since then, the city has added cameras, bringing the total to nine intersections, and the city is considering adding more, according to Moore.
The cameras are run by Redflex Traffic Systems, which got $89 per citation under the old contract with the city.
But the state has a new law prohibiting that arrangement, so the city negotiated a new contract that will pay the company $451,200 a year for its existing cameras.
The cameras caught about 5,400 red light runners in the last fiscal year, according to Moore.
BEHIND THE NUMBERS
Why are the numbers so muddy? Why do the cameras have a different effect at busier intersections?
"I do not know the answer," Moore wrote in an e-mail.
"When you are dealing with people and all that comes with them (inattention, cell phones, distractions, poor driving skills, and all the other unpredictable things) it's hard to come up with concrete reasons."
But when it comes to why people run right lights, he has one reason.
"It's inattention, is what it is," Moore said. "Totally inattention."
He said he asked for an examination of 100 random photos from the red-light cameras. On 39, he said, the driver was visibly talking on a cell phone.
Bakersfield drivers should drive defensively, he said. Before proceeding through a new green light, assume there's someone about to run the red the other way.
"A lot of collisions could be avoided if one or both was paying more attention," he said.
THE BPD ANALYSIS
Bakersfield Police Lt. Gary Moore examined the nine intersections with cameras and used the accident counts accumulated since they’ve been in place, and the accidents for an equal number of months before the cameras were installed. He also counted every accident the police knew about, including noninjury and complaint-of-pain accidents.
Overall, he found that rear-end collisions increased 8 percent and broadside collisions dropped 38 percent. But it varied dramatically by intersection.
At Coffee Road and Truxtun Avenue, broadsides rose by 9 percent even with the cameras in place, while rear-enders jumped 116 percent.
THE CALIFORNIAN'S ANALYSIS
We looked at nine intersections, too, but picked five with cameras and four without to see if increases in traffic were a factor.
And we used California Highway Patrol statistics from 1999 and 2006, not BPD statistics. Minor accidents aren’t reported to the CHP.
The picture these numbers present is muddy.
If you look at the intersections as two groups, then collisions increased where there are cameras and decreased where there aren’t.
Traffic flows increased about 30 percent for both groups.
But those groups also include intersections that are dissimilar.
If you focus on two high-traffic intersections near each other — Coffee Road at Stockdale Highway and at Truxtun Avenue — the numbers back up Moore’s contention.
At Stockdale, where there is no camera, there’s been a drop in rear-enders, but broadsides have remained stable.
At Truxtun, where there is a camera, there’s been a drop in broadsides, but rear-enders have remained stable. Traffic in both places increased about 55 percent.
INTERSECTION COMPARISTON
Intersections used for the BPD analysis (all have red-light cameras):
Bernard/Oswell
Chester/Brundage
Coffee/Truxtun
Ming/Real
Ming/Valley Plaza
California/Oak/Wible
California/New Stine/Stockdale
White/Wible
Analysis compared entire length of camera installation with an equal length of time from before the cameras were installed. That varied from 20 months (40 months total) at White/Wible to 50 months (100 months total) for Bernard/Oswell.
Intersections used for the Californian analysis:
With red-light cameras:
Chester/Brundage
Coffee/Truxtun
Ming/Real
California/Oak/Wible
California/New Stine/Stockdale
Without red-light cameras:
Gosford/Coffee/Stockdale
Coffee/Rosedale
24th/M
24th/F
Analysis compared 1999 and 2006 collision counts.