Minimum radius
Work in progress: This section is still a work in progress — content is being added and revised continuously.
What is checked? Every curve in your plan is compared against the minimum radius of your train categories (train profile). If a curve falls below it, the Plan check reports the tightest radius of the affected curve run.
Why does it matter? Long vehicles have fixed bogie-pivot spacings and close-coupled ends — on radii that are too tight, couplers bind, buffers lock, bogies scrape. Looks suffer too: an express train on first-radius curves resembles a folding ruler. Manufacturers state minimum radii for long cars; 420–500 mm is typical in H0 for 26.4 cm coaches.
How to fix it: Swap the curve run for the next-larger radius family (the plan grows a little), ease the route with flex track — or be honest in the train profile that only shorter stock runs here.
Numbers & defaults: minimum radius per train category in the train profile (default: express 420 mm in H0).