I went to a lift out bridge method. I wired 3' space on either side of bridge, I  used the magnetic door locks, like you would use for cabinet doors, I soldered a wire on each lock, Basically if bridge is removed power 3' back on either side is dead. It also locks the bridge down into the grooves.  Also on top of bridge I soldered a block of circuit board under each side of track  and soldered the rails to it then isolated it from each track. I hope this helps 

Ron,
  Thanks.  The magnetic door locks is a method I hadn't heard about.  One guy I know
did lift outs like you are doing and used "V-blocks" of plywood for locating/re-locating
the lift out each time it goes back in place.  Worked very well.
                                                                                                       - Jim in PNW

I also used V blocks cut from plywood. For repeated alignment. Magnets were for powering 2 track plus 3' on each side of bridge. I also made a swing bridge, using a door and door know as alighnment lock. Also powering each side and bridge.