The small footprint even of a double track line in Z Scale - which has an overall width of no more than 40mm / 1.6 inches - lends itself perfectly to a modular approach - just the ticket for someone wanting a layout which is not permanently on display but easy to set up and dismantle again in a sensible amount of time.
I initially went for a true minimum space formula with a width of just 6 inches (15 cm) for a double track line.

This still left some room for a scenic shoulder on both sides along the permanent way, but while this was okay for a flat Central Florida scenery, it proved too narrow for modules trying to replicate more varied terrain further North on the East Coast.

My accidental modelling thus led me in search of something just a little less minute, which is how I came across T-TRAK - a tabletop (hence the "T") modular system with individual modules which are a lot smaller than those of other systems.

(c) Unofficial T-Trak Handbook

(c) Australian T-TrakGroup

  Originally developed by N Scale modellers in Japan, the T-TRAK concept relies on the interlocking qualities of Kato Unitrack, which is the required brand of track (at least at the joining ends of a module). With the obvious similarity between Kato's N Scale and Rokuhan's Z Scale track (both have a moulded ballast base and a similar locking mechanism to join individual track pieces) the concept as a whole seemed interesting.

The Australian T-Trak Group has metric dimensions for Z Scale, and even though these are based on Micro-Trains track they are fully compatible with Rokuhan track. The depth of a standard module is set at 280mm with a width of 328mm; the track overhang on both module ends is a typical feature of T-TRAK which is supposed to ensure good interlocking (with e.g. Kato Unitrack) even between modules which aren't quite square (and therefore wouldn't fit well). The resulting small gap between modules is a defining trait of T-TRAK modules, but not everybody's cup of tea.

The modules are easy to build and comparatively easy to store, transport and set up. The "snap together" formula allows to put together layouts ranging from a simple circle to large complex layouts.

Developed for (and still overwhelmingly used for) N Scale, the idea has also been adapted for HO and Z Scale (recently incorporating the larger radii curves offered by Rokuhan by T-TRAK-Z), but given that I simply intended to have a modular layout which could be set up temporarily without much of a fuss I did not have to concern myself with the compatibility of parts of my layout with other modeller's modules - which is why I took the T-TRAK concept as a basis but introduced some changes according to my own preferences.

The most important change concerns the "interlocking" between two modules. I decided to use Rokuhan track for this modular layout; a close Z Scale cousin to T-TRAK's standard N Scale Kato Unitrack, it is fairly sturdy, but accidental knocking and damaging of protruding track was still a major concern.

The initial solution was to use the shortest piece of Rokuhan track (which measures 25mm) as a temporarily inserted "bridge" between two modules, thus setting back the tracks about 1,25cm from the edge of each module.

Four modules were built accordingly, but based on practical experience in setting up these modules, I decided to modify this "Mark 1" approach and plan subsequent modules to a "Mark 2" standard.

The main reason for this change was that aiming to have no gap between two adjacent modules in reality meant that there was no wiggle room for dimensional error, and in spite of best efforts put into the assembly of the module frameworks, the resulting track connections - albeit perfectly workable - weren't really a snug fit.


With the "Mark 2" approach, the connections between modules are made using 55mm pieces of Rokuhan track (R024). As a result, the modules now do have gaps between them, just as T-Trak modules do. The difference is that the track ends on any module are still set back, preventing accidental damage. The overall result is perfect connections and some wiggle room to iron out any potential problems.
55mm track pieces are now used throughout, even between "Mark 1" modules.

Designed as an extended oval layout, modules can be set up either for continuous single line running with a double track passing loop at one end, or for continuous double line running with a shortened inner oval.

Either way, the width across the corner modules is 67cm (26.4 inches).

Expansion is possible by adding an unlimited but even number of intermediate modules (only straight modules are pictured here for the sake of clarity).


  An important aspect of the modular segments is a strict adherence to level track, resulting in no inclines of the track itself while the scenery around it may rise and fall in all directions. Overall, this not only results in smoother operation but also makes connecting modules a lot easier.



page created 6 January 2016
last updated 31 July 2021