google.maps.VehicleType object specification
Possible values for vehicle types. These values are specifed as strings, i.e. 'BUS' or 'TRAIN'.
BUS Bus.
CABLE_CAR A vehicle that operates on a cable, usually on the ground.
Aerial cable cars may be of the type GONDOLA_LIFT.
COMMUTER_TRAIN Commuter rail.
FERRY Ferry.
FUNICULAR A vehicle that is pulled up a steep incline by a cable.
GONDOLA_LIFT An aerial cable car.
HEAVY_RAIL Heavy rail.
HIGH_SPEED_TRAIN High speed train.
INTERCITY_BUS Intercity bus.
METRO_RAIL Light rail.
MONORAIL Monorail.
OTHER Other vehicles. RAIL Rail.
SHARE_TAXI Share taxi is a sort of bus transport with ability to drop
off and pick up passengers anywhere on its route. Generally share taxi
uses minibus vehicles. SUBWAY Underground light rail.
TRAM Above ground light rail.
TROLLEYBUS Trolleybus.
https://developers.google.com/maps/documentation/javascript/3.exp/reference#VehicleType