Module Specifications

Module Requirements: 

  • A module must feature one or more modular ends, modular ends come in two types – see diagram.
    • 18” wide Single track module end – Width of the modular end must be 18”, a single track must be mounted centrally (track centre line 9” from either side) at 90 degrees to the modular end and must continue for 6” straight from the module end. (The 6” of straight track ensures that no S-bends are created by combining two modules, there will always be a foot of straight track between opposing curves on a main line.)
    • 20” wide Double track module end – Width of the modular end must be 20”, two tracks must be mounted at 9” from the nearest side, and 2” track centres. The tracks must be at 90 degrees to the module end and continue for 6” straight from the module end. (The double-track module end allows for longer passing sidings to be created on the single track by combining modules)
  • Module-sets need to be individually self supporting and not ‘lean’ on an adjacent module.
  • The end-piece of the module needs to be constructed with sufficient strength to accept the adjacent module being C-Clamped to it.
  • At modular ends: Top of rail above ground must be 45” – legs must allow for a ½” variance in either direction by using adjustable feet.
  • DCC track bus is connected by 4mm banana plugs (see diagram)
  • Modules with more than one modular end should feature at least one designated ‘main’ track that connects the modular ends together.
  • Main tracks, or any other tracks designed to be used by through trains must have a minimum of 36” minimum radius curves and #6 turnouts. Spurs and industry tracks must be 24” minimum radius and can use sharper turnouts.
  • Main line tracks must be code 83 (we use Peco as it’s now easy to obtain in the UK) – spurs and sidings that do not cross module ends can use smaller rail.
  • Scenery at module ends must be roughly flat with no features (such as roads, rivers or track other than the modular tracks) crossing modular joints.
  • Scenery at module ends should include a strip of greenery to disguise the module joint.

 Module Recommendations. 

  • Minimum curve and point specs are minimums. Your trains will look better on larger curves, and if you are building a module with a curved main line then adding transition curves will be very beneficial to smooth operations.
  • Be creative in your designs, follow a prototype’s curvature or add a junction or interchange.


  • There is no requirement for modules to be a specific width other than at the modular end.
  • There is no restriction on making curved modules apart from the minimum radius requirements and the need for a 6” straight at module ends.
  • There is no requirement for modules to be a specific length.
  • A module can contain any number of baseboards, and the internal baseboard joints in a module do not have to conform to modular specs.
  • Backscenes are optional – they do look nice on single-sided scenes but the centred track allows for modules to be connected in either direction, allowing for a curved module to become a left-hand or right-hand curve on the layout.
  • For info – if folk want to match our group uses Dulux Highland Falls -1 as a fascia colour.

Module End Diagram (click on the image to view):

Module End Diagram

Module Wiring (click on the image to view):

Module Wiring Diagram

The only requirement for wiring is for the DCC track bus, which consists of one wire for each pole crossing the board joint – some notes on the diagram:

  • Colour coding is shown only for clarity – boards can be connected either way round so the two rails cannot actually be reliably colour-coded.
  • We recommend (shown dotted on the diagrams) a bus wire to be run from one end connector to the other end(s) of your module – this will help with power transfer and ensure that a dodgy rail joint does not switch off every module ‘downstream’ of it!
  • You may add a connection into the DCC track bus to connect your own DCC system when it’s not being used on a larger layout.

 Other electrical issues: 

Pointwork needs to be controlled locally by your chosen method. Either through switch-machines controlled by a mini-panel (you will need to arrange your own power supply for this) or manually via push-rods or switch levers. If your points are manual please arrange electrical switching to make the frogs live.

 There is no requirement to build in a DCC control bus (such as Lenz X-Bus) – the reasoning behind this is that these modules could potentially be used on a layout running any NMRA-DCC system. There is nothing stopping you adding a bus and controller plug in panels for your own system – they will just be bypassed if the module is being used in a setup controlled by a different system.

For example – the RS Tower group use Lenz DCC, so some of the boards built by our own team will contain an X-Bus plug in – however we will also be using portable drop boards with X-Bus connectors to allow us to extend the X-Bus network to where it’s needed, even across boards with no control bus.



4 Responses

  1. Apart from the obvious mis-match of fascias, is there anything stopping a module of different width being connected for through running, assuming that the track centres and bus are compatible?

    • Hi Neil, not sure where you’re coming from exactly so i’ll try and cover as many of the bases as possible! 🙂

      Within the specs the 9″ track spacing from a board edge allows for a 20″ double track end to connect to an 18″ single track end if it should be needed (we prefer not to set up that way for visual reasons, but it does work if it’s needed) – that allows one of the two fascia’s to line up and there are no bus or track centre issues to contend with in that scenario.

      If you’re talking boards of a different width to the spec altogether, to a different modular standard maybe, then they should also be able to connect (assuming they have a flat end plate with no protruding locating devices, the heights match, and any track centres plus electrics are compatible or could be adapted to make them so) but looks-wise it wouldn’t be ideal. Some of the US Freemo setups seem to incorporate boards built to the old NMRA standard with two tracks towards the ‘front’ in this way, so it can be done if you accept the boards mismatch. If you’re regularly using it that way then it might be better to build a couple of short adapter boards though to make it look better?

      If you’re talking building something from scratch to go with this standard but narrower than the standard (say for ease of transport?) that’s probably do-able, but you’d need to make sure it’s stable, and need to ensure there’s enough width on the end plates to safely clamp them to the next board – *personally* i’d suggest building 18″ ends and narrowing it between the two module ends if you went that way.

      If you’re talking building something to go with this standard but wider than the standard that is *definately* do-able, but again i’d *personally* suggest having standard ends and widening the boards to suit your plan as needed between those ends – that would allow space to put a large yard, or industry, or large scenic feature on one side of the main track for example.

      My own ‘Alpha’ modules have an 18″ single track connection one end and a 20″ double track one the other end, there’a an angled piece near the end of the board that widens it without it looking too ‘sudden’, so modules that change width along their length are do-able.


      Martyn Read

  2. Thanks for your clarification. I belong to ‘Seaboard Southern’ who are broadly following your modular lead with our own standard of 24″ wide boards in 2, 4 or 6 foot lengths (Typically almost all are 4′ long) making for various different lengths of module. Single track at module ends is on the centre-line – (Where members have double track, this is equally spaced either side of the centre-line), as per your spec. There’s a lot of hassle at the moment over compatability issues should we have the opportunity to join up with other clubs’ efforts at some time.

  3. No probs Neil. In that case i’d confirm they should work together (subject to height/electrical connections as above) but obviously the joint won’t look quite as neat as neither fascia will be close.

    I suppose at a meet where there were a variety of types in use keeping the ones to the same standards together would help with the look (if it bothered somebody then an adapter board is possible?), but then on the other hand those are more likely to be meets (by folk taking part, and for folk taking part) than exhibitions (for the public) anyhow where the look is probably secondary to running it?

    Just out of interest, are you already building to 24″? We went for 18″ (like european Fremo) over the 24″ (like US Freemo) largely because it’s a lot easier to transport in generally smaller cars – you can get 2x 18″s next to each other between the wheel arches of most cars for example which potentially doubles what you can move in a car?

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