Autonomous switches

The trains are starting to progress, a few more mutations are needed for them to be just right. I am currently drawing out contact points for the structure to meet with the extensions off of these trains. One contact spins within the frame. This was to allow a train to pass through the narrow corridor but still have the capability of extending outwards. When the arm hits a adjacent structure, it will just spin inwards and maybe to the other side. A spring loaded bumper has been introduced to allow for train to train collisions. The arm extensions have been designed so they can be fitted on almost any element of the frame. The intent is to have a series of autonomous devices move along the tracks, and trigger contact switches which will activate moving devices above and below.

A couple issues i have been running into:
1) Acrylic is not forgiving, easily cracks when joints are tight, and tolerances needs to be tighter.
2)Grounding strip catches onto the rail line, needs to be smoothed out on the bottom.
3)Trains still need to be fine tuned and tweaked to be more consistent in movement.
4)Wheels spinning out, need to get tires for wheels attached to gear and motor, or use a rubber gasket.

I came across this video clip of the mail bag retrieval of the trains.