The doors swish shut and with the press of a touchscreen button, the Personal Rapid Transit (PRT) car is off, gliding through the tunnels beneath Abu Dhabi's new Masdar City. The sleek four-passenger vehicle — which looks like something out of the movie TRON: Legacy — runs on an electric motor, making it clean and carbon-free. There are no tracks — the car is autonomous, driven by a computer that charts direction with the help of tiny magnets embedded in the road. When my PRT car senses another vehicle waiting in our parking space, it stops and waits for the area to clear, avoiding a collision. PRT is meant to be the future of mass transit within cities, with the environmental benefits of buses and trains but the freedom of a private vehicle. But as my car pulls into an open docking bay, I can't help thinking there's something slightly silly about all this. For all the technology — which isn't cheap — the PRT has taken me to its one and only stop, maybe half a mile (800 m) from the starting point. For a lot less — and not much more time — I could have used a much older form of transport: my legs.



The topic sentence introduces the P.R.Ts and it explains how its good for the environment, how the cars travel, and how the technology runs the autopilot car.