HOUSTON - A study by the Texas Department of Transportation indicates that overall collisions were reduced at dozens of intersections that had red-light cameras installed.

The report released Tuesday by the department concluded that crashes declined overall by 30 percent at a sampling of intersections, the Houston Chronicle reports in its Tuesday online editions.

"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 looked at 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 were reduced by 43 percent, while rear-end collisions increased by 5 percent.