A vehicle traffic site is any corridor or structure whose space is designated for the passage of vehicles in transit between any other sites. This usage is applied to roadways and any structure which accommodates roadways, such as tunnels and bridges. It is not applied to structures such as tollbooths and parking garages, which vehicles may pass through, but whose primary purpose is not to facilitate the transportation of vehicles.

The site's principal purpose must be passage between other places. Vehicles passing through a parking garage or tollbooth do not alone establish this use.

The route can run on a roadway or through a bridge or tunnel. The enclosing structure does not change the transportation purpose.