There are numerous references to Facing Point Locks on Spring Switches within ABS as used by the Southern Pacific. I know what a facing point lock when used in Interlocking, but a spring switch would have different considerations.

A train approaching a spring switch for a facing point movement must be prepared to stop short and hand operate the switch unless it receives a proceed signal or there is a switch point indicator. I could see where a train making a facing point move at a good speed could get in a whole lot of trouble if the spring/buffer system failed allowing the point to move. I assume an approaching train would cause an electric locking mechanism to lock the points for a facing point move, but the circuit could not lock it in front of a trailing move from a diverging route and would have to unlock to allow it to hand throw.

I never ran into one of these or hunted one down. Anyone familiar how they work?