Track-activated accessories (gateman, semaphores, etc.)

I power all accessories from a transformer that does not power trains.  I use one "common" bus for all transformers. The power for a given accessory may come from another transformer, but the train wheels will complete the circuit when on an insulated track section which is connected to the common bus.

You are correct, all of the transformers must be in phase.

I connected the common/return of all (4) of my transformers together.  I only use two transformers to operate the trains.  The "hot" of one accessory transformer is dedicated to powering my switches via the fixed voltage plugs, the "hot" of the other is assigned to track powered accessories - gateman, crossing gate, switch tower.  Train speed remains unaffected and there's no need to isolate each insulated track section.

Pete

ps - Looks like Owen beat me to it.

Yes, by all means use a dedicated power source for your accessories. But don't confuse that with the power supplied to the insulated track sections. That's just "regular" track power.

This is what I do on my Lionel PW-style layout with a ZW: I use either the B or C output posts and run a "bus line" for power. Each operating accessory taps into the bus line separately and they all go back to one of the common posts. This way you are using a dedicated power source for the gateman, etc. and don't experience the voltage drop when using track power.

If not using a ZW you can do the same thing with another transformer dedicated to accessory power.   

OK, I think I understand what you're all saying.  I'll have to work on it, but I think I get it.  I was locked in (pun intended)  that the "switch" from the wheels hitting the insulated track had to be powered by the same power source (transformer) as the track. 

Not sure if I'm using the terms correctly here, but here's how I've set up in the past. For simplicity, assume loops/mainlines with no switches or sidings.  I'd connect a transformer to the center rail of each loop.  Then instead of running a second wire from each loop's outer rail, connect ALL the loops' outer rails to a single, common "bus line" and route it back to one transformer. Then, at the transformers, run a wire from post to post connecting the transformers.  Can't remember if these were the "A" or "U" posts, but I've got that written down somewhere.  Basically, what I hear you saying is to do the same for the accessories, right?

Oh, one other related question.  With the new layout, I'm going to use Lionel Powermasters so I can control the track voltage with my CAB-1 (so I can run conventional engines without being at the transformer).

Does that negate the ability to connect all the outer rails to a common/share bus line? In other words, do I have to run 2 wires to each powermaster directly?