11/20/2007Houston Red Light Cameras Fail to Prove Safety Benefit
After a year of red light camera use in Houston, Texas there is no evidence that the devices have saved lives.
One year after the installation of red light cameras, Houston, Texas Mayor Bill White declared the program a success, claiming the devices have led to a "dramatic decline" in the number of accidents. Further investigation by local television station KPRC suggests the ticketing devices may not have created such a clear-cut safety benefit.
A total of eighteen camera systems have been operating for the past year. KPRC compared the number of accidents one year before the devices were installed to one year after and found that ten intersections showed fewer collisions while seven showed an increase. In the case of the intersection of FM1960 and Tomball Parkway, the jump was a staggering 220 percent.
The number of accidents at a given intersection fluctuates from year to year so that a single year's results can sometimes be misleading. This is especially the case when cameras are installed at intersections that, in one year, happened to have an abnormally high collision rate. A statistical error known as "regression to the mean" occurs when the natural drop in the number of accidents to a more normal level is ascribed to some other cause, such as red light cameras.
KPRC's investigation also noted that cameras were installed in at least four intersections where collisions were extremely rare. Mayor White admitted factors other than safety went into the selection of camera locations. White promised a report in January that would show the benefits of the devices which have generated millions in revenue for the city.
View KPRC's accident spreadsheet (18k PDF file).