Personal Rapid Transit (PRT)
Numerous PRT systems have been proposed but only a handful are as yet operational, one of which is the 21-vehicle ULTra system at London Heathrow Airport’s T5. ULTra pods run on rubber tyres, like funfair “dodgems”, and move rather slowly in narrow open guideways with low walls to keep the pods in place. Since the pods use batteries rather than power from the track, the system has clearly been built “on the cheap” and is not as futuristic or innovative as is hyped.
Personal rapid transit (PRT), aka “podcars”, is a mode of public transport using small automated vehicles operating on a network of guideways. PRT pods are designed for individuals or couples or up to 4 per per vehicle. Guideways are arranged in a network topology with stations located on sidings with merge/diverge points, thus allowing nonstop point-to-point travel, bypassing all intermediate stations. A driverless point-to-point transport mode is akin to an elevator, except it travels in a horizontal direction.
Mass transit systems are designed to move large numbers of unrelated people over scheduled routes. This has inherent inefficiencies. Passengers waste their time waiting for the next vehicle to arrive and then waste more time at numerous bus stops/stations en-route. Routes tend to be indirect, and schedules confusing or inconsistent. Constantly stopping and starting huge weighty vehicles like buses or trams uses a lot of energy, thus undermining the environmental benefit of public transport.
Personal rapid transit systems attempt to eliminate these wastes by moving small groups nonstop in automated vehicles on fixed tracks. Passengers can usually board a pod immediately upon arriving at a station, and can take relatively direct routes to their destination without stopping. The low weight of PRT’s small vehicles allows much smaller guideways and support structures than mass transit systems like light rail. Smaller structures mean smaller construction costs and less visually obtrusive infrastructure. However, as of now, a citywide deployment with many lines and closely spaced stations, as envisioned by proponents, has yet to be constructed.
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