An investigative reporter's claim that Florida cities have been exploiting shortened yellow times at red light camera intersections has been vindicated by a report commissioned by the city of St. Petersburg. WTSP-TV's Noah Pransky has been documenting timing shortfalls throughout the region since last month, and a new report by the engineering firm Kimley-Horn and Associates confirms several of St. Petersburg's photo enforced intersection approaches fail to meet the minimum specified under state law.

On Thursday, the city council's public service and infrastructure committee discussed the issue and the signal timing report that Councilman Charlie Gerdes had requested in April, in spite of assurances he had received from city staff that the yellow times were verified and correct.

"Another question related to a traffic signal's yellow time or clearance interval was made," city transportation director Joe Kubicki wrote in an October 18, 2012 memo to the city council. "All signalized intersections were reviewed by staff prior to the start of the program and all locations with traffic safety cameras were inspected by the Florida DOT prior to a permit being issued to ensure all meet or exceeded the state required interval. Clearance intervals meet or exceed all state and national requirements and have not been adjusted at any location."

That statement proved not to be true, according to the findings of the engineers at Kimley-Horn, who collected 24 hours' worth of vehicle speed and signal timing data at each of the ten intersections with red light cameras. They found half of the photo enforced intersections had problems with shortened yellows.

At 34th Street and 22nd Avenue South, the northbound and southbound approaches were short by 0.8 seconds -- Florida Department of Transportation rules mandate the time should be no less than 4.3 seconds, but the light was timed at 3.5 seconds. At 66th Street and Tyrone Boulevard, the northbound and eastbound approaches were short by 0.7 seconds -- 3.6 when they should have been a minimum of 4.3. At 4th Street and 54th Avenue North, the northbound and southbound approaches were 4.0 seconds when they should have been a minimum of 4.3 seconds. At 66th Street and 38th Avenue North, the southbound approach was also 4.0 seconds when it should have been at least 4.3 seconds. At 66th Street and 22nd Avenue North, southbound approaches were 4.0 seconds when they should have been a minimum of 4.3 seconds.

When the actual speed of traffic is used to calculate the absolute minimum yellow time instead of the posted limit, 34th Street and 1st Avenue North northbound proved short by 0.2 seconds -- 4.0 to 4.2 seconds.

A fraction of a second difference in yellow time can have a massive influence on the number of red light camera citations issued. The vast majority of straight-through red light "violations" happen when a driver misjudges the end of the yellow light by less than 0.25 seconds -- literally the blink of an eye (view Texas Transportation Institute (TTI) chart). In most cases, a yellow shortened by one second can increase the number of tickets issued by 110 percent, according to a TTI report. Confidential documents uncovered in a San Diego court trial prove that the city and its private vendor, which now operates as Xerox, colluded to install red light cameras only at intersections found to have short yellow times (view documents), thereby maximizing profits.

St. Petersburg gave American Traffic Solutions the right to issue citations in October 2011. As of March, the firm has been able to issue 47,715 tickets worth $7,538,970.

A copy of the yellow time report is available in a 200k PDF file at the source link below.