Click a row to show its two roads; delete puts it in the list to apply.

Crossings (A over B) the solver could not keep, because of the joins around them: the part of A's casing that crosses B and is drawn under B's fill is red. Click one to open the pair, then switch off or add a part, or change a join nearby.

Parts of A that only come near B (they do not cross it), drawn under B's fill: the solver keeps these last, after every crossing and order wish. Worth a look only where the two roads overlap on the map.

"A after B" wishes (found or yours) the solver let go: A's fill is not after B's. Two wishes that disagree, or a wish against a stack, end up here.