Yellow times may shorten as the city of Billings, Montana rushes to install red light cameras before the state legislature has a chance to ban them. The Billings City Council voted 8-3 Monday to empower Redflex Traffic Systems, a private company based in Melbourne, Australia, to issue automated traffic citations in return for a cut of the revenue collected. Billings needs to act quickly because the state legislature last Thursday entered into final negotiations on legislation that would ban red light cameras.

After the House had passed legislation banning red light cameras without conditions, state Senator John Brueggeman (R-Polson) added a grandfather clause to the bill that would allow Billings, Bozeman and any other city that enters into a contract before the bill is signed to issue photo tickets without limitation. House members voted 58-42 against this loophole and insisted on convening a conference committee with the Senate to negotiate the final language.

In a memorandum to the city council, Billings Police Chief Rich St. John foresees the prospect of increased revenue from shortened yellow warning phases at intersections equipped with red light cameras.

"Changes in the yellow times after red light camera systems are in place and operational will affect the number of photographed violations, increasing the number of violations when yellow times are shortened and reducing the number of violations when yellow times are lengthened," St. John explained in a memo dated April 8. "Where changes in the yellow times at intersections with red light camera systems are required as the result of updated speed surveys or other factors, the changes should be clearly described in public information announcements. Providing warning notices for a reasonable amount of time after the change is particularly important for violations recorded at intersections where the yellow interval has been shortened."

The Texas Transportation Institute (TTI) in a 2004 study documented the effect of reducing the amount of warning given to motorists before an intersection signal changes from green to red (view study). Cutting one second from the yellow time formula endorsed by the Institute of Transportation Engineers (ITE) in 1989 boosts violation income by 110 percent. Adding one extra second to the 1989 ITE formula slashed violations by 53 percent. Lawmakers in the state of Georgia recognized the value of longer yellows with a law mandating one extra second. Since it took effect in January, violations plunged 80 percent and profit dropped to a level that has forced seven cities to cancel their photo enforcement contracts.

The TTI also recognized a 40 percent reduction in collisions from longer yellows and an increase in crashes of between 125 and 225 percent from shorter yellows. St. John foresees the possibility of increased crashes in Billings after the installation of cameras.

"There was some concern about an increase in motor vehicle accidents as a result of motorists slamming on their brakes to stop for a changing light and getting rear ended by the motorist following them," St. John wrote. "There have been conflicting studies over the increase or decrease of rear end accidents after a photo red light enforcement system is put into use."

View independent studies documenting the accident impact of photo enforcement. A copy of the St. John memo is available in a 150k PDF file at the source link below.