The TTI study included 11,000 crash records at 275 intersections with red light cameras, many of them here in Houston and in other big Texas cities like Dallas and El Paso. Troy Walden is a research scientist who authored the study. He says overall
crashes at those intersections were down 11-percent.
"As far as red light violations and the crashes that are associated with those violations we found a reduction rate of about 25-percent and then the overall right angle crashes, which are the most dangerous and hazardous types of crashes that occur at the intersections we found a crash reduction rate of about 32-percent."
The study compared crash frequencies one, two and three years before and after red light cameras were installed. Walden says the data didn't support claims that rear collisions increase at red light camera intersections.
"While these types of crashes, they're not insignificant, they were a very small share of the total number of crashes that occurred and really there was about three in every 100 crashes was a red light related type of rear-end crash, where an individual slammed on their brakes to avoid running a red signal and was hit from the rear."
Critics of the cameras say they're not about safety but instead a way for cities to make more money. Walden admits some intersections in the study did show increases in crashes after red light cameras were installed.
"The majority of those particular intersections that showed such a significant increase or decrease in crashes were those intersections that had a very low number of crashes to begin with, so any change in rate for the number of crashes affected the percentage of change in a negative way."
Houston's red light cameras are back on after going dark after last year's referendum against them. The city turned them back
on to avoid a lawsuit from the vendor that set them up in the first place.