A simpler way to deal with red light runners
Some parts of the country like to deal with red light runners by putting up those cameras. Then there's Silicon Valley, where technology is all over the place, except when it comes to handling red light violations. Instead, they use a neat little hack called the Rat Box.
The Rat Box is just a little light which is mounted on a traffic signal head and can be aimed "downstream". That way, you can station an officer in a prime spot to pick up people who run a light. Better still, since the officer is downstream and out of the way, they don't have to also run that red light to catch the offender.
Sometimes you'll see more than one aimed in the same general direction. I suspect in those cases, one is for traffic headed straight, and the other is for those turning left into that same space.