[buro9]

Those maps look extremely similar to UK canal maps: http://www.macclesfieldcanal.org.uk/mcmap3.htm

These tended to be made into an almost straight line and printed on a single piece of paper with notable junctions and features only.

It would've been obvious at the time that the format would be ideal for fixed routes that these could be scrolled.

[helb]

Something similar is often used for railway lines. Even Wikipedia has it on some pages, eg. https://en.wikipedia.org/wiki/Great_Eastern_Main_Line