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This behavior does only exist in the editor mode.TL;DR
In editor mode: when rails cross, only delete one segment instead of all.What ?
When deconstructing a highlighted rail segment, actually all segments on that location get deconstructed. In the shown example, the curved and the straight rail segments get deconstructed.To deconstruct only the curved rail, one can easily select it with the mouse. However deconstructing ONLY the straight rail is impossible, same goes for crossings of pure straight or curved rail segments.