I am retired from a Transportation Department of a large metropolitan area and some of us retired types get together with some of our still working friends for lunch every month. The guy who was placed in charge of the red light camera project commented that after the first year of use that the city was losing revenue but T-Bone and rear end accidents had declined dramatically. The number of contested tickets that defendants won in court was staggering and the costs of employees who had to be at each trial were astronomical.
There was no collusion between the City's DOT and the contractor that supplied the cameras but it was intimated(by one of the traffic engineers) that the contractor asked for changes in signal timing, which was denied. Finally the councilmen instructed the City Attorney to end the contract for failure to produce the expected revenue generation.