Tail track
Work in progress: This section is still a work in progress — content is being added and revised continuously.
What is checked? At switchback spurs (destination reachable only via a reversal): is the run-round segment long enough for a locomotive plus one car?
Why does it matter? To work the spur, the locomotive with at least one car must fit completely onto the intermediate track before pushing back. If it is too short, the spur is effectively unworkable — one of the most common “wish I’d known” mistakes on real layouts.
How to fix it: Lengthen the segment by the shortfall (often just one or two track pieces) — or dismiss the finding with “Ignore” if the spur really is worked only by the small diesel: the plan check uses fixed lengths here, not the locomotives of your trains.
Numbers & defaults: locomotive + car = 260 + 264 mm (H0, scaled), fixed — the trains in your train profile do not change it. A run-round segment is only reported if it is shorter than the locomotive alone; a longer one counts as an approach track, not a tail track. Without your own trains the rule is paused. You set up your trains in the “Operations” tool, which is coming soon.