Motor vehicles / cars crashing into buildings

building - a structure with roof and walls

I can bivvy under that bridge because it has a roof and it has walls, so building it is (albeit a little breezier than a bus stop).
Thanks OED.

The OED says a bridge is "A structure carrying a road, path, railway, etc. across a river, road, or other obstacle."

Also, a bridge doesn't need to have walls. E.g. the Millau Viaduct - no walls. Nobody could conceivably call the Millau Viaduct a building, therefore.