A trap point prevents the main line being fouled by vehicles running away from a siding . The points divert vehicles into ballast or a sand trap and are locked into this normal position with routes set on the main line. After a movement through the trap point in the reverse position, trap points usually have self-normalisation which move the point to the normal (protecting) position. If there is no self-normalisation then an indication is often presented to the signaller to indicate that the points should be normalised manually.
Last edited by GeoffM on 15/09/2016 at 03:00