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There have been numerous instances where the contractor responsible for managing the cameras decrease the time on yellow. Their contracts generally include profit sharing and if there are not adequate tickets handed out they lose money.

I am a licensed professional engineer in a company that specializes in this kind of engineering work. Over the last few years I have made a number of offers on this site to represent -- free of charge -- any Freeper who has been given a traffic ticket at an intersection where one of these alleged "decrease the yellow time" schemes was in place.*

There is a very specific method that is used to compute yellow intervals for traffic signals -- based on various conditions at each intersection, including posted speeds on the intersecting roadways, sight distance, allowances for increased stopping distance under certain weather conditions, etc.

To date, I have not had a single poster here accept my offer.

* My only condition is that I get 10% of any monetary damages that are awarded in civil court as a result of any lawsuit that would surely follow such a finding. I would also take great pleasure in filing all of the necessary paperwork to have the engineer responsible for such a disgraceful travesty brough up on formal ethical/disciplinary charges before the appropriate licensing board in his/her state.

You should get in touch with the National Motorists’ Association - http://www.motorists.com/ - they’ve been following the red-light camera issue for years.

To wit:

January 14, 2002 - “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] (there was no public disclosure of the yellow increases when they happened or the results from making them)

Don’t you recall that San Diego was sued and that shortening of yellow intervals was documented and proven in a class-action lawsuit resulting in the cancellation of thousands of tickets and removal of red light cameras?

http://www.thenewspaper.com/news/00/63.asp

4. After the red light program began in San Diego, at least two intersections had their yellow light phases shortened by a full second before the computer-enforcement devices were installed. The intersections were: (1) Grand Avenue and Mission Bay Drive; and (2) Mira Mesa and Scranton Road.

...and...

One of the computer-enforced intersections, the intersection at Grand Avenue and Mission Bay Drive, had citations drop from more than 1,000 per month to less than 50 per month when the yellow light time was increased by 1.7 seconds – from 3.0 seconds to 4.7 seconds – allowing drivers sufficient time to react.

“There is a very specific method that is used to compute yellow intervals for traffic signals — based on various conditions at each intersection, including posted speeds on the intersecting roadways, sight distance, allowances for increased stopping distance under certain weather conditions, etc.”

They don’t have stop light cameras in Florida where I’m at. The times I’ve been in Dallas I’ve managed to avoid running any red lights.

The cameras are run by computers,correct? So while there is a specific formula by which the timing should be set the value is set by a person. That person can make a mistake or can set it incorrectly.

IMO stop light cameras are solely about revenue generation and not about safety.