TL;DR
Show some type of numerical indicator when placing new signals/stations, for how many train cars can fit between signals/stations.What ?
When placing a new signal or train station (or ghost), numerically display how many train cars (regardless of type) can fit between the potential placement, and the next signal/station before or after it.Having the numbers rotate with different arrow directions would solve the "does left mean up or down". I'm not a UI/UX guy, so I don't have a suggested solution for how to implement that, unfortunately.
Why ?
Visual feedback is king.This makes adjusting things on-the-fly much easier, especially for long trains and/or signals which go off screen. It allows for visualizing things more easily and quickly.
It'd be especially helpful for signals in front, so that you don't have to plan things out in a specific direction or meticulously down to the singular rail placement. Lay it out, place the signals, then add a track or two if necessary at the end.
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