In the fog if you suddenly see a big hole in the road it isn't all that unlikely that accidents from trying to avoid them could happen. There also may be cop just standing there checking out the paint markings for some reason
Ideas like this inevitably fail because they don't generate income like a camera and only cost maintenance. Speed cameras make money even though they are generally ineffective. Of coarse I'm the bad guy because a car with a loud exhaust doing 5kp/h more than the speedlimit is an immediate danger to the public
