Verb. When using a subway system, to prewalk is to use the time while waiting for a train to walk to the spot on the platform where you will board the train so that when you get off the train at another station, you will be at a desired location on the platform, e.g. stairs, turnstile, or corridor to another train.
Noun. The walk required to get to a desired spot on a subway platform as described above.
You want to prewalk? We'll save time.
Do you know the prewalk for this transfer?