Insulating rail joiners are available from at least one manufacturer of track. It’s probably not a good idea to try to run trains on separate tracks using one single-outlet controller. One controlled outlet per train is the general rule. This could take the form of three individual controllers, each with a single controlled outlet, or a single and a double, or even a 4-controlled output controller; I’m not aware of any controllers with 3 outlets, but they may exist.

Part A – preventing short circuits: Each track section must be separate from the others, either by being a totally separate loop/line or by having insulated rail joiners where they connect to other sections. Bachmann EZ track might have something for this. Otherwise, remove the electrical contacts at the ends of the adjoining tracks or put something like electrical tape over them so they don’t make contact.

Part B – independent directional control. You’ll need three DPDT switches. Wire them as shown in the diagram. Once installed, these switches control the direction, not the one on the power pack (which will still work, but it will reverse all three track sections at the same time). When driving from one track section to another, make sure the direction controls agree.