Editing Personal rapid transit (section)

====Switching====
Almost all designs avoid [[Railroad switch|track switching]], instead advocating vehicle-mounted switches (which engage with special guiderails at the junctions) or conventional steering. Advocates say that vehicle-switching permits faster routing so vehicles can run closer together which increases capacity.  It also simplifies the guideway, makes junctions less visually obtrusive and reduces the impact of malfunctions, because a failed switch on one vehicle is less likely to affect other vehicles.

Track switching greatly increases headway distance. A vehicle must wait for the previous vehicle to clear the junction, for the track to switch and for the switch to be verified.  Communication between the vehicle and wayside controllers adds both delays and more points of failure.  If the track switching is faulty, vehicles must be able to stop before reaching the switch, and all vehicles approaching the failed junction would be affected.

Mechanical vehicle switching minimizes inter-vehicle spacing or headway distance, but it also increases the minimum distances between consecutive junctions. A mechanically switching vehicle, maneuvering between two adjacent junctions with different switch settings, cannot proceed from one junction to the next. The vehicle must adopt a new switch position, and then wait for the in-vehicle switch's locking mechanism to be verified. If the vehicle switching is faulty, that vehicle must be able to stop before reaching the next switch, and all vehicles approaching the failed vehicle would be affected.

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.