It is, TTe (or TTn2.5 or TTn30!), I've done three layouts in it, two of which have been in CM! Also N gauge equipment can be used for TTm (TTn3) as well. I have some Shapeways prints knocking around for that one. I found Z to be a bit of a s*d to get running correctly, especially in TTe where speeds are so much slower than you see in SG Z, at least that's where the Rokuhan stuff came in handy, they were nice, smooth, runners when I'd sorted out the controller. Quite honestly my operators and I were glad to get back to 9mm and 12mm gauges! Both show what can be done in TT, though, with railways in the scenery, Alber (the first one) was 6ft long and the other just under 11ft.