Another method of energizing the rails is thru square brass dowels and micro switches for safely de-energizing rails on both sides of a void.
The use of doubled cabinet magnets help secure the bridge. Can be used as a single or double.
Single use magnet seen below:
The East abutment dowel powered the + rail the West dowel powered the - rail. Wires were soldered to the opposite end of the male/female dowels for connections to the buss or rail.
The rocker switch is used for cutting power to tracks on each side of the opening.
In the 18 years of using these setups on many RRs there has never been an interruption or hesitation of power delivery.
Armchair critics have scorned this method in their one and only visit.