Be curious what thos two large rectifier blocks are used for in circuit. Appears that Marty is right that its AC, though without seeing baord and tracing circuit, it might be possible to run on DC (note I said MIGHT be possible as it looks like the 13-20 VAC is rectified and stepped down to 5, 8 or 12VDC to run the timer, optoisolator and relay and most likely not interconnected at all with the AC train wiring)
My guess is when trolley touches Trigger the optoisolator turns on triggering the timer that makes relay open the REVERSE track circuit. After timeout, relay closes restoring track power to REVERSE section. Not sure how they hold off timer from re triggering when wheels touch TRIGGER section again as it leaves section.
