Actually, if speed cameras and red-light cameras are there to actually increase safety for all drivers and pedestrians, they either have to be ALL over our city, or not at all. When they had them in Toronto, they were sparsely laid out. There were very few of those cameras, and IMO, this doesn't work. People know where the camera is and slow down, while the only people who pay the fine are speeders who aren't familiar with the area.
If you ever drive in a place like Taipei, where cameras seem to be everywhere in some parts of the city, everyone drives within the limit because they have to.
My point: Either go all out and litter the city with speed cameras, or don't bother putting them up. Otherwise, they generate a lot of revenue without making the streets any safer.