Baseboard for portability

[Brian]

Nice woodwork, but large IMO. Usually 4ft x 2ft (1200mmx 600mm approx.) I have found is about right to easily move around. especially if scenery is fixed to it. A 9mm ply top well supported is great.
The only thing I would have done before fixing the top to the bracing timbers is to have drilled a few 15mm dia. holes in the cross bracing. These allow wiring to pass around under the board. It is much harder to drill them when the top is fixed down.

A word of caution, as you mention older track (1980's). This may well be steel rail which is very prone to rusting. Test with a magnet, any magnet will do even a fridge magnet. Steel it will attract while modern Nickle Silver rail it wont. If its steel personally I would avoid using it as it can lead to very poor running.

Sorry that all sounds very negative. But setting off on the right course is IMO the best way of progressing without too many issues arising later on .

[Tricky Dicky]

I seem to recall the intention is to keep the layout in a shed and bring it into the house when in use. 50 X 25mm is fine when used fixed to a wall or other permanent structure but I think you risk quite a lot of movement with the changes of temperature and moisture levels.

I would suggest you cut some of that spare plywood into 100 - 150mm strips and fasten that to the all the sides and that should stabilise things better. I would second Brians implication that the board be split Into smaller linkable sections to aid portability as your baseboard will likely be populated with many delicate structures all making manhandling through openings somewhat perilous.

[stonesfan]

All of the Hornby steel has been binned. Have bought Peco points and already have a load of Peco flexible long lengths. All my curves are now Hornby Nickel Steel (magnet test).

Will suck it and see when it comes to portability. If it finds a permanent home then I may even extend it a couple of feet. But I'm a big strong bloke and don't mind carting a bit of weight about from time to time. The other half has already offered to help with movements if it means keeping it out of the bedroom!