A railroad for express trains.
A racetrack with optimum conditions for high speeds
The quickest or most direct method or path.
A high-pressure or intensely competitive situation, particularly one characterised by rapid advancement.
To progress something with unusual rapidity.
A rapid transit rail transport system, or a train in such systems, generally underground and serving a metropolitan area.
An urban rapid transit rail transport system, normally with lighter track and light trains (i.e. an S-Bahn or similar), or a train in such systems.
A metropolitan area.
metropolitan