 Conventional steering allows a simpler 'track' consisting only of a road surface with some form of reference for the vehicle's steering sensors.Switching would be accomplished by the vehicle following the appropriate reference line- maintaining a set distance from the left roadway edge would cause the vehicle to diverge left at a junction, for example.Several types of guideways have been proposed or implemented including beams similar to monorails, bridge-like trusses supporting internal tracks, and cables embedded in a roadway.