The #175 double crossovers are 32" long and 4.5" center rail to center rail. Because of the distance between the center rails in the middle diamond a dz1008 relay ($25) may be required to stop a stall. It depends on your specific center roller pickup spacing. Unfortunately, the manufacturers of trains have no set standards for this so you never know. We recommended dropping the two wires down from the center diamond as per the instructions in case you ever get a locomotive that stalls, so you can easily connect the relay. Wiring it in is easy.