Officials in Richland Hills, Texas have manipulated the yellow signal timing at the city's lone red light camera monitored intersection. By slicing the amount of warning time available to motorists from 3.6 seconds to 3.0 seconds for several months, the intersection of Glenview Drive and Booth Calloway Road generated an estimated $300,000 in extra photo ticket revenue. Richland Hills Police Chief Barbara Childress admitted that she ordered the yellow signal time shortened.

"I had actually reduced the time," Childress admitted to KDFW television.

Childress' account of why and when this change was made, however, was inconsistent with the facts. She first claimed that the "speed up" effect of the MPEG compression used with Redflex online violation videos confused her, leading to an unfortunate order to shorten the signal timing below the minimum standard established by the Texas Department of Transportation. MPEG video compression does not speed up videos. Second, city documents assert that the signal timing had only been shortened during a thirteen day period in August (view documents in a 520k PDF file), evidence provided to KDFW television proved otherwise. Violation videos from June 9, July 28 and a motorist's videotape of the intersection from August 11 and 14 documented that the signal was providing just 3.0 seconds of yellow, as opposed to the 3.6 seconds provided before the ticket cameras were activated.

The effect of this manipulation was significant profit. With yellow at 3.0 seconds, the number of $75 violations was 700 percent higher than when the timing was at 3.5 seconds. The timing was reset back to 3.5 seconds on August 28 (view chart showing effect of signal timing on violations). The yellow signal time's effect on photo ticketing is documented in a 2005 Texas Transportation Institute study that found an extra second of yellow added to the bare minimum ITE recommended amount could yield a 40 percent reduction in collisions.

By lowering the yellow time and raising it again in August, the city produced a "drop" in violations that it could use to suggest the camera itself had produced a significant safety improvement. Correction: An earlier version of this story mistakenly identified the intersection involved as being located in North Richland Hills, a neighboring city.