Well, there are speed traps and there are 'driving modification incentives'. Speed traps are mainly for income, and set up a condition where it's hard not to break the law. The cameras are supposed to prevent red light running, but some are set up so that you can enetr on a greena and the light will be red before you get through.
I'd love to see traffic cameras in every intersection in San Francisco's financial district. It's scary to drive through there with all the red light runners. During evening traffic there's frequent gridlock as people drive into the intersection even though there's no way to get out of the intersection due to other traffic. This sets up a chain reaction that ties up traffic for hours.
In many areas the cameras are owned and operated by a vendor on behalf of the city. The vendor installs them in exhcange for a percentage of the fines. The vendors sell cities on the concept much as they lobby them for other contracts.
In my city, a Red Light Camera Company (RLCC) offered to so a demo at their own expense. The RLCC installed the equipment at a freeway offramp. Then they 'tuned' the traffic signal to work with thier system. It turned out the 'tuning' included shortening the yellow light interval to increase the number of infractions. Set to the normal intervals there were not enough violations to pay back the RLCC's investment.
There used to be a true speed trap in Marina Ca, a little coastal town next to the Fort Ord army base. Coming into town was a downhill slope, and the speed limit dropped from 55 to 40 and less than a block later was 30. A few blocks further it was back up to 35. The cops with radar sat at the 30 MPH sign and popped you if did not drop the extra 10 MPH. Since it was downhill, it was easy to pick up a little speed without noticing it.
Daniel
, so I really don't know.
