The Motorway

The Motorway was part of the mass transit infrastructure of New New York. An immense sealed tunnel, it was divided vertically into lanes, each lane apparently comprising one layer of traffic. The Fast Lane, which occupied the lowest level, was restricted to vehicles with three or more occupants. Attempts to contravene system protocols resulted in the steering wheel of the vehicle locking.

History
The population of the upper levels of the city was destroyed by a mutant plague as a result of widespread use of the mood drug "Bliss". The travellers in the Motorway were unaware of this. Unable to leave, they simply thought that the exits were closed for repair and kept on driving around the system, thinking that by the end of their second circuit the exits would have been reopened.

Access was still restricted, eventually resulting in a tremendous traffic jam and journeys lasting decades. The situation was exacerbated by the presence of large numbers of apparently devolved Macra in the lower reaches of the system. The Doctor was able to open the Motorway exits and allow the drivers trapped there to repopulate New New York. (DW: Gridlock)