I have a question: We have a tag for speed traps installed at a specific point (highway=speed_camera) but do we also have a tag for the section control type speed traps used in the UK, Italy and Austria? (See: http://en.wikipedia.org/wiki/SPECS_%28speed_camera%29 )
Have you checked the wiki? It seems like a good idea though.
I have checked the wiki, but I have not found anything.
You could use the enforcement relation
You tag the camera node with role device, add a maxspeed to the relation and tag the start and end points.