Tuesday, December 02, 2008

Scarce data makes new TXDoT study on red light cameras suspect

I stopped following the red light camera issue closely on Grits after I left ACLU of Texas, primarily because nobody was paying me to track the topic, which involves a lot of local fights and bitter back-room legislative controversies among hardball-playing, money grubbing combatants. But I've followed the issue enough in the past to be surprised when a reader sent me the link to a Houston Chronicle story which reported today that:

Red-light cameras apparently reduced overall collisions at dozens of monitored intersections across Texas, according to a state transportation study.

The report, released today by the Texas Department of Transportation, concludes that crashes declined overall by 30 percent at a sampling intersections, many of them in Houston.

"While these results cannot conclusively determine that red light cameras are responsible for the overall reduction in crashes," the report reads, "the presence of the treatment provided some effect on the frequency of crashes at the selected intersections for the limited time period of this analysis."

The study examined crashes from July 1, 2007 to June 30, 2008 at select intersections at 12 cities required to report crashes under a new state law.

The data show that right-angle collisions reduced by 43 percent, while rear-end collisions increased by 5 percent, mirroring some other studies across the nation.

Here's a link to the full study pdf. (As an aside - why can't newspaper stories link to their sources just like bloggers do?)

These are surprising data that contradict many past studies on the topic. For example, in Lubbock red light cameras were discontinued after accidents overall increased 52% at intersections with cameras. Similarly, the state of Virginia eliminated their use after studies in every city using the devices found the number of accidents increased. In other jurisdictions, studies have found reductions in right-angle accidents but nearly equal increases in rear-end collisions, including in injury accidents.

So how did this study come up with such radically different results? The short answer may be that much of their data is incomplete and speculative. For camera operators who began before 2008:
there is no requirement for the local authority to provide a report to the Texas Department of Transportation concerning the 18 months of pre-installation crash data even if the system remains active in 2008. ...

This presents a problem in reporting since some local authorities reported preinstallation crash data while others did not. This made the process of analyzing the effectiveness of the red light camera system difficult to perform since no base line data was present for some local authorities. In short, there was no metric to determine the rise, fall or static percent difference in crash rates at some of the reported treatment intersections.
Similarly, agencies' post-installation data was often truncated, particularly for jurisdictions that only began their programs since the beginning of the year. So the researchers had to take limited datasets and analyze them projecting forward.

Only 12 of 26 cities provided pre-installation crash data; two of those 12 did not provide any post-installation crash data. For that matter, "Of the 24 cities that provided post-installation intersection crash data, 14 failed to provide pre-installation crash data." It seems likely that pre-installation crash data may be under-reported, especially for rear-enders, since many people don't call the police over a minor fender bender but the camera will pick up everything.

So researchers ended up with an extremely small dataset from intersections chosen because other data was flawed or non-existent, not because it was representative of the whole: "Ultimately, there were 10 local authorities that provided pre and post-installation intersection crash data. The information provided represented 56 different intersections within these 10 reporting communities."

In addition, we know in many cases agencies don't report all their crime data to the state on many more serious types of offenses. So one wonders whether reporting on traffic accidents contains similar gaps and errors.

Finally, while other factors may contribute to accidents, researchers only looked at a single variable so it was:
difficult to determine the impact that red light cameras had as a safety countermeasure because other crash variables could have produced a biasing effect on the number of red light running collisions that occurred. As such this analysis provided only a limited descriptive investigation of the self-reported local authority red light camera data that was provided to the Texas Department of Transportation.
These pre- and post-installation data shortcomings, along with an outcome so radically different from other longitudinal studies, make this report highly suspect, IMO. But then, I'm biased toward using engineering solutions to reduce red light running instead of reacting to every problem by mulcting the public with tickets and fines.

Going forward, at least for agencies whose cameras came online after the new law took effect, it's possible that we'll have reliable data for analysis in the future. But there really doesn't appear to be enough data here for researchers to come to any real conclusions.

BLOGVERSATION: More from Blog Houston and Lose an Eye, It's a Sport.


Anonymous said...

Family questions police officer's shooting death of Albany man
By Celinda Emison , Jared Fields
Monday, December 1, 2008

Family, loved ones and friends are still in shock over the shooting that claimed the life of Michael Wayne Richardson early Saturday morning in Breckenridge. Richardson, 37, of Albany, died from a single gunshot wound during a confrontation with police, initial reports said. Family members say they want a full investigation into the matter -- and that Richardson's death was unnecessary and tragic. "Our hearts are so ripped out," said his mother, Connie Jackson, of Breckenridge. The case has been turned over to the Texas Rangers. Sgt. Shane Morrow of the Eastland County office is the lead investigator and could not be reached for comment Monday. At 12:36 a.m. Saturday, Breckenridge police received a call about a vehicle accident in the 500 block of North Court Street. A 2007 Dodge Ram pickup, driven by Richardson, 37, apparently had run through an intersection and into a fence, according to a news release issued by the Texas Department of Public Safety. Richardson may have been trying to flee the scene, but the vehicle was caught on the fence and he spun his tires as he tried to rock the vehicle free, the release said. Officers said they repeatedly tried to get Richardson's attention, but he apparently did not acknowledge their presence and did not turn the vehicle's engine off. According to the DPS report, Breckenridge police officers on the scene believed Richardson attempted to lift and point a firearm at them, and he was shot.
His mother said her son carried a .22 caliber rifle in his truck and had been hog trapping Friday afternoon. He later went with a friend to Potter's Bar & Grill in Breckenridge. "The bartender asked him to take another guy home and he did," Jackson said. Family members said Richardson drove less than two blocks after dropping the man off when he hit a mailbox and then a fence on Court Street.His father, Wayne Richardson, also of Breckenridge, was waiting for a call from the Texas Rangers Monday afternoon."There needs to be a deep, deep investigation into this matter," Wayne Richardson said. "There is just something not right about this." His uncle, John Henry Jackson, said he examined the truck after the shooting."There were at least seven bullet holes shot through the passenger-side window and four to five shots in each tire, except the left front tire," he said. "I believe the tires were shot out after he was already dead." Richardson's father called him a fantastic young man who had never even had a speeding ticket. "Everybody loved him," Wayne Richardson said. "He was a kind, gentle person. I just hope we can get a reasonable conclusion to this case."A few years ago, Richardson was lauded as a local hero after rescuing a pregnant woman from a car that slid off an embankment during an ice storm.
Those who knew him said he was known as a happy person who loved to golf, hunt and fish. A lifelong resident of Breckenridge, Michael Richardson moved to Albany two years ago after a divorce.
He worked as a field engineer for Basic Energy Services of Albany for almost 14 years. "He was like a son to me," said his boss Ronnie Anderson. "He was a great employee and had a great attitude. I know one thing, he did not deserve what he got." He loved his family, his children, Bryant, 12, and Bryson, 14, and his stepdaughter, Lindsey, who had just given him his first grandson, Jaxson, Connie Jackson said. "He would have never raised a gun at a police officer, much less fire a shot," Jackson said.
Richardson's sister Brandy Sirianna, said her big brother always protected her. The two spent Thanksgiving Day together, which was the last time Sirianna saw her brother. "I still can't believe it and still don't understand why they did that to him," Sirianna said. "He didn't ask for it." His mother said the family simply wants justice. "I want the person or people responsible for my son's death held responsible," Jackson said. "They took my first born and the father of my grandchildren away from me." A memorial service is tentatively set for 2 p.m. Sunday at Bethany Baptist Church in Breckenridge, under the direction of Morehart Mortuary.

© Abilene Reporter-News

Anonymous said...

Traffic safety data absolutely contains gaps and can be intentionally (or unknowingly) skewed by officers performing crash reporting.

An example is contrasting two law enforcement agencies' crash report policies. For a while agency A took the position that if you call us out, we'll take a formal crash report and submit it to Austin, even if the damage was less than the $1,000 threshold for reporting in state statute. Agency B in many instances ignored state statute and refused to write a formal crash report for non-injury crashes that did not result in a vehicle being towed, even if the crash resulted in well over $1,000 damage.

Thus the two areas would have dramatically different property damage only crash numbers.

Also, lets compare the Data in CRIS with the self reported data at some of the locations to make sure the camera programs are reporting the same data they report to Austin.