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 train that runs on such an underground railway.
An underground route for pipes, sewers, etc.
A rapid transit system, regardless of the elevation of its right of way; a metro system.
An underground railway, especially for mass transit of people in urban areas.
An underground walkway, tunnel for pedestrians (called pedestrian underpass in US).
To travel by underground railway.