S-curves can be a railroader’s worst nightmare, yet they are a feature of many track plans because they can add interest to a layout. If you are going to add an S-curve, plan it carefully. That means that you need to have at least one straight section of track at as long as your longest car between the curves. Otherwise, regular derailments might become unwanted events on your layout. Fixing a problematic S-curve can be exceptionally hard once the track is permanently placed.

One of the most challenging placements for an S-curve is just beyond a turnout. Avoid having a curve in the opposite direction immediately after the turnout diverges. Follow the straight section between changes of direction practice mentioned in my post of 19 Nov 2024.