What do the subtypes on trips represent?

Attribute	Description
	The route represents a driving route. (The vast majority of routes are driving routes!)
	The route represents a walking route. Obviously, this applies to long-distance trails such as the Appalachian Trail, but it can also represent walking routes through cities and involve road walks.
	The route represents a bicycling route.
	The path follows a route that can be taken via public transit—as far as Google can determine.