There's been no more glue-ing at my end while I worked out the road side of things, as I want to have the design well-specified before I do anything irreversible. As previously mentioned, for LUCK I'm rolling with the Unitrack thing and designing the road to work with Kato Unitram specs. In practice, you can't really use Unitram as-is because they only have pieces to fit a 62x62 grid, and none of the "fudge" pieces Unitrack-N does.

Anyway - as with the mainlines of ex-CLACK (C-Track, defunct), MLACK (M-Track), LUCK (Unitrack-H0), NACK (Unitrack-N), BLACK (Tillig B-Track) and ZACK (Rokuhan Classic Track) (but not LOCK, because there's no O-gauge curves that fit in a 550mm shelf, much less Lionel Fastrack ones) the position of the tram track has to be aligned based on doing a curve over a corner module; and the edge overhang also has to be identical to the mainline. My initial design had this actually fit with Unitram parts. Hallelujah! It used an edge alignment of 18mm.



But ah - you see the obvious problem. Given how expensive Unitram is; why would you want to start cutting it up? Not to mention it makes putting scenics in even more awkward.

So I had a crack at doing it without stressing on using only-Unitram because - well, what's the point? None of the other baseboards are exact multiples of 62mm so you're always going to be doing DIY hard-standing if you choose to put tramlines on your boards. What's one more? I still wanted a variant that was only using set-track though - and I came up with this:





It still uses the Unitram curves because - well the standard N curve parts don't work at that track separation. But a 46mm and 124mm in the middle give correct alignment with a tasty board-edge margin of 13mm - almost back to the original 10mm I yolo'd for CLACK before I got the hang of the math.

And it gets better - using set-track, you're stuck with the 150mm curves of the Unitram inner track of course. But using 20-099 and Flexitrack, you can get a constant radius of about 290-310mm around the board - which is enough for most OO9 or N stock to run on. The "standard" will assume 150mm, but it's nice that you can make boards compatible with bigger stock if you put the work in. Now - making a caul for the corner modules is just a little trickier - and I'm tempted to say the spec-way of doing this is to attach two pre-built LUCK boards and hold the track aligned with those. I don't really like the additive errors that can introduce, but it's more likely to be accurate than some DIY construction; given that the cauls will be too big for most people to print, and would be long enough that angular error is likely to come in anyway.

So, I'm pretty happy with 13mm as the road margin and 62mm x 7mm as the road dimensions. That can apply to any of the modular systems - In H0 scale it's just a narrow gauge track inset into a single-carriageway or single-lane road; and if you work at TT or N it's a large single carriageway with a narrow or standard-gauge tram - and at Z you can ignore the tramline and just call it a dual carriageway.

Oh; and yeah - as implied above I also worked out the straight-line math for TT/H0m, Z/H0f and O. I haven't calculated the alignment for Z because - honestly I just don't think it will actually work very well given the tiny track tolerance; I just thought it was funny that I could. And I haven't calculated it for TT because I don't have any B-Track to measure the track width. And O can't do curves so you just stick it dead-centre of the shelf and have done with it.

I still don't think NACK boards should be made in preference to T-TRAK or Hex-TRAK because those are likely to stay much better adopted, but if you work multi-scale or multi-gauge there's nothing to stop you making some NACK and LACK boards and a dual-gauge converter that links the two. As far as I know though there's no TT/H0f modular standard, so it's nice that one is kind of falling out the side of LUCK/MLACK as a side effect.