In this paper some mathematical tech­niques are illustrated for catalogu­ing railway layouts, the interconnect­ed points protected by home signals that together form the “crossroads” in our railway networks. The need for such a catalogue might arise for sev­eral reasons. Firstly, there is the po­tential of cross-validation on a micro scale. Reusing interlocking code or circuit plans for identical layouts on the own network simplifies the vali­dation of that specific railway appli­cation. Secondly, there is the possible gain in design time, most clearly in­teresting when suddenly confronted with the need to rapidly create new interlocking code or circuit plans: re­using this information from another identical layout could save tremen­dous amounts of time, when such is possibly scarce. Thirdly, a network should be as simple as possible, but not any simpler. When our catalogue would permit layout comparisons, network complexity analyses could be enriched.