try ''60 plans for small railways''...a peco booklet.
I have more or less replicated what I seem to recall is their 2nd or 3rd plane.
I have used a board smaller than 6x4....more like 5'6" by about 3'6"......to fit in my lads bedroom over the stairwell block...it folds in half as well......
whilst I am rubbish at providing diagrams, I can describe as
follows:-
a basic oval, on the long sides passing the baseboard edge within about 1-2"...enough for coach clearances...same on two short sides.
because I used flex track, the left side is 'waisted' a bit in towards the centre..about 2", provides a bit of relief from straight track.....something to avoid on a small board....also allows slightly tighter curves, but important to relieve each bend..ie lead in gently....
on the right side...using curved points (setrack)...starting at top and bottom [short side of board], a passing loop...thus, looking from short side, left side single track, right side loop.
This loop is in an 'S' shape like the left side....ensure the curves of the inner track dont exceed tightest radius setrack curve.
from the inside loop, a RH point leads off into the middle, towards the rear.....the curved portion forms the curve of the loop, bringing its direction back parallel to the long side edge of the board....alongside its outer brother.
the spur off leads to a bay platform.
platforms are built both sides of the loop, at the far end...ie up the long side, curving around to the top middle...where the loop starts.
so the inside platform has the bay behind it.
immediately the bay road leaves the main line (loop)...another small wye point leads to another spur.....originally a goods shed.
however, my son bought a peco turntable kit......and despite its innappropriateness..I had to ffit it in, so I ran a kickback offhtis second spur, to the foreground inner area, and built in the TT, with an engine shed.
there was another spur comming off the inner loop, opposite end to the platforms...which curved around inside the main running line..to a pit for loco servicing....this before the appearance of the TT!
the left side top end of the running line is in a tunnel...one tunnel mouth being visible...the ide for the other end is, where it leaves the station, to disappear under a girder road bridge, into a fake cutting......to disguise the fact it comes back on itself...the layout being viewed more or less from one and a half sides only..due to walls.....