Heh...we wuz jokin' that they need a rating system for ours - color code or something. You see signs up before the worst of 'em, but they all just say "Bump". That can mean anything from "your car will bounce a bit" to "your vehicle is about to be eaten alive".
If you see a HOMEMADE sign, that's usually an indication of the later variety, and you'd best say yer prayers quick...
Er...latter variety.
that and the smoke and flames from the previous victims is usually a good indicator...