If there is more than one pathway between the same pair of signals, the interlocking may be set up to allow routing via one only, some pathways, or all pathways. With no other restrictions in place, such as locked points or other routes set, the interlocking has a "preferred route" which will always be set in preference to anything else. The remaining routes are called non-preferred routes.
Last edited by GeoffM on 15/09/2016 at 03:01