I believe the back spike is in case of a rollback of a train not clearing the first hill. PK is a full circuit but it is a 'disconnected full circuit' for lack of a better term. There is a transfer track that connects the lower end portion of the ride to the upper portion where the back spike and launch area is. The transfer table goes up an incline due to the topography of SDC which amongst other things is going to make this a unique ride.
Glad to know that PK will most likely be up and running on March 17 when the park opens for the season.
JW