I'm not sure...
I was going at 110 through there, after being on the hume at 110, and only saw the camera at the last minute, I braked and I haven't recieved a fine yet, so either they're not functional or I slowed down enough not to get caught...
They're infra-red ones though, because when you drive past them, at the right angle, you can see a weird beam of light. So they have to be working...