We have a few time/distance cameras on a few of the freeways here. I travel them often and use cruise control. I laugh at the idiots who speed, then slow down for the camera, only to speed up again. Little do they know they will still get fined for doing the set distance in under the allotted time, hence speeding. If ever there was revenue raising cameras, I don't think there is a better example. However, if you want to limit the speed on a section of freeway, its probably a good way to do it.