# Is there a word for the round-trip time of a train line?

On a subway line, trains go from the starting terminus to the other terminus, and then back to the starting terminus. Is there a word that is usually used to refer to the time it takes for a train to travel as described?

"Round-trip time" seems to be mainly used when referring to packets on the Internet.

This is the context in which I want to use this word: "The blue line has a shorter _______ than the green line, so fewer trains are required."

EDIT: I would like to specifically refer to the time taken, not the distance covered (since the time taken could depend on lots of other things, like the waiting time at each station and the speed at which trains travel). For example, the word "headway" specifically refers to the time interval between consecutive trains, instead of the distance between them. (The distance between them changes as they travel on the subway line, but the headway never changes (assuming an ideal situation where each station has a fixed duration for which every train must wait, and each track has a fixed speed at which every train must travel).) I am hoping that there is a similar train-specific term for the duration that I am describing.

• Round trip is what it's called. You can buy one-way tickets or round-trip tickets. And you can ask how how long each type of trip takes. Sep 28, 2018 at 15:51
• @JasonBassford "Round trip" seems to usually refer to a commuter's trip (which does not necessarily reach the terminus), instead of the train's trip? But I would like a word that specifically refers to the time, rather than the path or distance. Sep 29, 2018 at 4:17
• What about just the blue line is shorter than the green? Sep 29, 2018 at 5:51

It’s not clear if question is for

• linear track e.g. `A-> B -> C -> B -> A` or
• a ring track e.g. `A -> B -> C -> D -> A`.

For a ring track consider circuit:

The blue line has a shorter circuit than the green line, so fewer trains are required.

... or perhaps for a either ring or line a shorter (or faster) route works.

If your prefer to focus on time not distance and track is a a ring then lap time may work:

The blue line has a shorter lap time than the green line, so fewer trains are required.

Or if there is variance, you could say average lap time.

• +1 for circuit and circuit time. Not sure I like lap time for this though.
– Jim
Sep 28, 2018 at 21:20
• The word "route" seems acceptable somewhat, but doesn't it still refer somewhat to the path/distance, rather than the time? It doesn't seem to give the same focus on time like the word "headway", which is specially used to describe the time interval between trains. Sep 29, 2018 at 4:14

What you are looking for is a cycle.

"The blue line has a shorter cycle than the green line, so fewer trains are required."

MW:

cycle

noun

2a: a course or series of events or operations that recur regularly and usually lead back to the starting point

A word often used in this (and broader) sense is turnaround (also turnaround time).

"The blue line has a shorter (quicker) turnaround than the green line, so fewer trains are required."

Collins:

noun

2.

the total time taken by a ship, aircraft, or other vehicle in a round trip