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.