Grade
Work in progress: This section is still a work in progress — content is being added and revised continuously.
What is checked? The grade of every route section (from the track heights) against the limit. If most of a ramp lies in a curve, the finding says so — the grade acts effectively steeper there.
Why does it matter? On a ramp a locomotive doesn’t just pull the train, it lifts it. Rules of thumb: 2 % is comfortable, 2.5 % the upper recommendation, 3.3 % only for small layouts with short trains, 5 % a last resort. For very long trains (15+ coaches) stay below 1.25 %. European locos with traction tyres pull far more than models without them.
How to fix it: Lengthen the ramp, reduce the height difference — or, at over/underpasses, split the difference across both tracks (one drops, one climbs): halves the required ramp length.
Numbers & defaults: limit 2.5 % (editable).