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This section focuses on NTRAK standards, one of a number of N scale modular standards as outlined in the N Scale Module Standards document.

NTRAK represents a concept for building modular layouts for settings in homes, at clubs and public displays from small to very large.  The standards outlined in compact form on this sheet allow modules to be built in distant places, and yet they will fit smoothly into a common layout. This sheet is designed as a quick overview and reference. General layout of a module:

Legs adjust ±1" (25 mm) 

Power Connections:

 Accessories, Side by side Black to right, both ends alike:

Track power left end, Second color on top:

Track power right end, Primary color on top:

 Modules are joined by setting two “C” clamps and inserting a 5” connecting track. Remove ties from track ends as needed to allow rail joiners (Atlas, Peco) to slide fully on. The clearance from the clamp to the top of the rail is typically 4½”.

To obtain a square module, make the lengths L1 and L2 equal, the end depths E1 and E2 equal, and the diagonals D1 and D2 equal.

Module table:

  • Length: multiple of 2’ (610 mm)
  • Depth: 2’ (610 mm)
  • Skyboard: min. 8”, nominal 14”

The most common length is 4’. Optionally, 6” depth can be added at the front and/or rear. Each module should have its own legs. Bridge and other special modules may be used with the approval of the layout coordinator. The module owner shall provide two “C” clamps per module, size at least 3”.


Three tracks are obligatory for all modules and are considered “community property”. Placement of the track centers, measured from the rear of a 2’ deep module, is at

  • 20.0” (508 mm) front main, “red”
  • 18.5” (470 mm) inner main, “yellow”
  • 17.0” (432 mm) branch line, “blue”.

Track positions are defined at the ends of a module or module set. The first 4” from the end (edge) must be straight. Internally to a module (set), the minimum track separation is 1.25”. A number of optional tracks have been defined, see the table below. The minimum distance from the front edge of the module to the center of the first track is 2”.

Recommended track material is Atlas Code 80 flex track, Peco Code 55 flex track, or Kato Unitrack. Modules are connected with 5” Atlas Snap track sections (nominally 4.91”) or Peco Code 55 flex track cut to the same size. Community property tracks must be compatible with large wheel flanges and must accept the standard connecting track. The module owner shall provide connecting track sections as needed.

Crossovers between the three community tracks are suggested for long (6’ and up) modules; turnout sizes of #6 or larger are recommended. Among other options, uncoupling ramps have to be electrical, and tunnels have to be easily accessible for track cleaning and rerailing of rolling stock.


Track power and optional accessory power shall pass through underneath the module in 12 AWG stranded copper zip wire, extending 12” beyond either end of the module. Feeder wires for tracks and accessories can be attached with suitcase connectors (3M 567, brown) or by soldering them to the bus wires. Connections between modules use Anderson Powerpole 30 A rated connectors. The community tracks and a number of established optional tracks have unique color codes assigned. The color codes are applied to the connectors by selecting proper colored shells or by wrapping them in colored tape (no black tape, other second colors are applied as thin stripes). For track power, the primary color shall mark the wire feeding the front rail of the track.

Do not use common rail wiring. There should be no connection between any of the rails of the three community tracks. Crossovers need to have insulating gaps in both rails.

The above specifications are available for download as a two-page Summary.

The complete specifics document is also available for download.  Questions can always be directed to

Possible extension

Up to to 6" may be added to both the front and rear of modules to make room for scenery or track plans. If extra is added at the rear, the skyboard should still come forward in some manner to match the standard position.

The Wiring and Connector standards are documented in 2011 Standards for Wiring and Connectors. Available for download is the Wiring and Connectors Recommended Practice which covers wiring and  Powerpole Connectors.

How Standards get modified:

How do standards get changed? In some organizations, there are very elaborate and complicated processes that involve committees, peer review and a great deal of time. And then there is the situation where a change is handed down from on high and no one is really sure how the decision was made or who was involved. NTRAK was at one end of the spectrum while Mil-Spec standards are at the other end. Sometimes standards do not get changed because there is no way to change them or there is too much resistance to change. Recently, NTRAK did make some changes to its standards. Most of those were simply adjusting the standard to conform to what was being practiced. Interestingly the standards went out for review several months before the vote was taken, but most of the comments and reaction came as soon as the voting was announced. One of the questions that was raised was how are NTRAK standards changed? This was coupled to a suggestion for a change, relating to track. Since we do not have a documented procedure, now seems like a good time to put together the guidelines for future reference. First, any member may suggest a change to the standard. The suggestion should be accompanied by:

  • Detail on the change, which may include dimension, or usage or procedures related to the change.
  • Why is this change being suggested? How would it benefit the NTRAK community?
  • What are the consequences of the change? This should include any negative aspects as well as those that are positive.
  •  What is the timing for the change? Should it become effective immediately, or should it be something that can be phased in over a period of time such as the updated wiring standard?
  • What is the effect on compatibility. How can we maintain the ability to mix existing modules in with those that implement this recommended change?

The proposal should be submitted to the board in writing or through a letter to the Newsletter editor. The board will present it these requests to the membership for discussion on a yearly basis and allow for at least a period of three months, encompassing time for publication of the proposal and one issue of the newsletter and comments in the following issue. The board may or may not make a recommendation to the membership and that recommendation can be either positive or negative. Finally, the proposal will be presented to the membership for a vote.

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