In January, 2002, the city of San Diego, California released a study that they claimed was an independent report that supported the city's plan to expand their red light camera program. The report was conducted by PF Farradyne (PBF).
Although the report clearly credits the most significant reduction in violations to an increase in yellow time - a fact buried on page 78 - the majority of the report credits these benefits to the red light cameras. This is misleading considering that the intersections with the greatest improvement in violation reductions had their yellow time increased.
"The most significant change in the number of violations occurred at the intersection of Mission Bay Drive and Grand (1541) where the yellow change interval was extended from 3.1 seconds to 4.7 seconds. This change resulted in an 88-percent decrease in the number of violations. At the five other intersections, the number of violations dropped significantly in response to longer yellow times." ["City of San Diego Enforcement System Review Final Report", PB Farradyne Inc., January 14, 2002, Chapter 6 (Traffic Engineering and Traffic Operations Improvements", page 78]
Further, the PBF report does not establish whether the cameras were operational 24-hours a day or not. Without this, you would see misleading reductions in "violations" from cameras that are taken out of service, run out of film, or are just plain turned off to achieve the desired reduction in violations.
The report is also far from being independent or neutral.
In 1999, Parsons Brinkerhoff (the "PB" in PB Farradyne) made one of the largest contributors ($5,000) to a group pushing a ballot measure to increase sales taxes for, among other things, red light cameras in Chandler, Arizona.
PB Farradyne admits as much when they wrote a proposal asking the City of San Diego to select them to do the "independent" report. The city obviously made their decision based on the independent criteria found in the proposal, such as the following:
The NMA opposes the use of red light cameras and proposes engineering solutions as the real fix for intersections with high accident rates.