Current edition v2.0.3 — May 2023, including the TT-scale addendum. Revision history
T-TRAKAustralia Field Guide

A field guide to T-TRAK modular model railways in Australia.

Tabletop, portable, and built to a community standard. T-TRAK is the modular system that lets a module built in a Hobart shed click cleanly into a row at a Brisbane exhibition. This guide covers N scale, HO/OO, TT and the Mini-T variant — every dimension, every part number, every paint code.

Open the standards What is T-TRAK?
SKYBOARD · 200mm visible · light blue REAR · KATO UNITRACK FRONT · KATO UNITRACK 308 mm 300 mm 33 mm centres 38 mm front setback +1 mm protrusion FIG.01 · N STRAIGHT MODULE · 308 × 300 × 70 mm · TOP VIEW · NTS
FIG.01 / N · single straightSource · v2.0.3 §N2
Browse the guide

Eleven sections, four scales, one community.

The standards are organised so a builder can dip in to whatever they need next: a single straight tonight, a corner module next weekend, a wiring diagram the night before a meet.

§ 01About T-TRAKOrigin, philosophy, the LEGO analogy. § 02SpecificationsDimensions across all four scales. § 03ConstructionCut lists, hardware, build sequence. § 04ElectricalBLUE → outer rails, RCA, PowerPole.
§ 05ScenerySkyboard, fascia, paint codes. § 06JoiningClick together, spring apart. § 07VariantsJunction, inside corner, single track. § 08MeetsTables, mains, module info form.
§ 09Layout planningStarter to capital-city dog-bone. § 10TroubleshootingTwelve common faults, fixed. § 11ReferencesRevision history, contributors, glossary. § FAQFrequently askedQuick answers to common questions.
Scales

Four published standards.

Each scale has its own footprint, track geometry, and Australian conventions. The Australian N scale uses a 300 mm depth — 90 mm more than the international standard — which is the most visible deviation.

308 × 300 × 70 mm

N scale · 1:160

The default Australian standard

Single straight 308 × 300 × 70 mm. Track centres 33 mm. Kato Unitrack. The most-used scale in Australian T-TRAK practice.

N scale specifications
490 × 490 × 70 mm

HO/OO scale · 1:87 / 1:76

Bigger module, bigger trains

Single straight 490 × 490 × 70 mm. Track centres 60 mm. Skyboard 350 mm visible. Same Kato Unitrack philosophy, scaled up.

HO/OO specifications
413 × 400 × 70 mm

TT scale · 1:120

The newest addendum

Single straight 413 × 400 × 70 mm. Track centres 43 mm. Tillig Bedding Track. Added to the Australian standards in May 2023.

TT scale specifications
— × 150 × 70 mm

Mini-T · N variant

Smaller footprint, more flexibility

150 mm wide, 62 mm length step. 12 mm hardwood ply only — pine and MDF warp at this size. A sub-system for tighter spaces.

Mini-T specifications
First principles

Five rules that hold the whole standard together.

If a module follows these five, it joins. Everything else is detail.

1 · Track overhang+1 mm each endUnijoiner bridges the 2 mm gap.
2 · Module lengthtrack − 2 mmFor N: 308 / 618 / 928 / 1238 mm.
3 · PolarityBLUE → outerFront rail of front, back rail of back.
4 · DC feed cadence≥ 1 / 9 mNo measurable loss to nine metres.
5 · Track grade0 % levelMainline only. Yards, anything you like.
From the guide

What's worth knowing first.

Three modules joined

§ 06 · Joining

The Unijoiner does most of the work

Power flows between modules through the Kato Unijoiners themselves. There are no separate connectors at module joins, nothing to solder, nothing to fail.

How modules join
Sky · Earth · Signal

§ 05 · Scenery

Pale blue sky, eucalyptus green, earthy ground

The recommended palette by brand and code — Berger Polar Breeze, Colorbond Wilderness, Dulux Grey Scape. Bare wood is not acceptable.

Paint codes & scenery
BLUE → outer rails

§ 04 · Electrical

One rule for the whole layout

The blue wire of every Kato feeder goes to whichever rail is on the outside. White goes to the inner rails. White RCA = front, red RCA = back.

Wiring & bus
A community standard

Australian for a reason.

Australia is an island, materials at the local hardware are not the same as in Tokyo or Texas, and the layout we set up at a hall in Bendigo is shaped by the boot of the car we drove in. The Australian guidelines codify the local conventions so a module from Hobart still drops into a row in Brisbane.

The standards are maintained by a small group of contributors, edited by Andrew George and published from St Arnaud, Victoria. The current edition is version 2.0.3, dated May 2023, and includes the new TT-scale addendum.

See the contributors and revision history →

VIC
Victoria
NSW
New South Wales
QLD
Queensland
SA
South Australia
WA
Western Australia
TAS
Tasmania
ACT
A.C.T.
NT
Northern Territory

Modules travel from any of these. At a meet, the coordinator tags each one with its state of origin.