by martink » Mon Nov 20, 2017 11:23 am
As Doug has been saying, setting up a block system on a single track / dogbone layout like this has more than a few potential pitfalls and complications. Also, size - it works well for layouts like The Bridge & Sarum Bridge because each track section is 4m-5m long. More than one train can be moving at the same time, while on a smaller layout each train has to take its turn to shuffle forward one section.
That's why most people go for a plain double track scheme with two controllers, keeping the two lines completely separate. My new one will have it both ways - double tracks, each with its own block control, and with some additional size-related refinements taking advantage of the visible and non-visible sections.
A year or so ago, Ozrail was playing with a really sneaky scheme to use the standard Eishindo PWM controller and its two sensors to have two trains following each other around a layout similar to yours, but I haven't heard anything more about it. One train stopped in the station until the other was about 2/3rds of the way around, then it started, then the other took its place at the station. That only required the standard kit, half a dozen diodes and two isolating track pieces. However, there were two potential drawbacks: the sensors really needed to be mounted at an angle to the track to ensure reliable train detection (possibly requiring a bit of surgery on the sensor base and the piece of track), and the diodes cause a noticable voltage drop and hence poor low-speed running.
The key is deciding EXACTLY how you want your layout to run. If you are planning to fit the points at a later date, then just having a isolating section for each loop lets you manually select one train to run.
For one of your other questions, if you do go for a block system then I would probably recommend against using common return. Its main purpose is to reduce the amount of wiring needed for a large layout with dozens or even hundreds of sections, but the advantages are minimal for a smaller design. However, since the controllers are battery powered, it would work fine. Six of one and half a dozen of the other.