The terminal rerailer is connected via terminal wires to a power pack, which provides current to power the layout. In addition to making power connections, the terminal rerailer is designed to correct derailments that sometimes occur during normal railroad operations. It can also be used to help properly align wheels on the track when assembling a train for operation. If you want to use the rerailer to help place cars on the track, you should install it so that it is easily accessible. Otherwise, it should be installed after a difficult section of track (turnout, crossing, ?S? curve, etc.) where derailments may occur.