Raising the Bar for N Scale Modular Railroading

Standards and Recommendations

Revision 7


Free-moN attempts to raise-the-bar for N scale modular railroading by specifying standards for bench work, track and digital control that promotes, and even forces, prototypical appearance and operational characteristics. This document contains standards that must be followed to the letter and recommendations, in italics, that have been gathered from various sources.


These are the goals that the standards presented here are attempting to achieve as they apply to N scale. Each standard set forth below must satisfy at least one of these goals.

The Free-moN standard has the following objectives in mind:

  • To promote and require hi-fidelity prototypical scale model railroading.
  • To ensure reliable track and electrical operation.
  • To encourage visual continuity between modules.
  • To encourage a loose association among individuals free from club memberships, dues and titles.
  • To keep the standard specifications to a minimum without compromising the previous objectives.


Any component (or group of "sections") of bench work that is meant to be operated as a single unit in a fixed configuration. A module can have any number of sections. The ends of a module comply with the mechanical standards defined in the Framework description, below.
A component of a module, complete with bench work, track, scenery, etc. Except where otherwise noted, standards for module end interfaces do not apply to inter-section interfaces, as these are considered to be internal to the module.
Endplates are the standardized end surfaces of a module, usually two, that join to another module.

1.0 Framework

Framework refers to a module's structural frame including endplates, legs, braces, decking, etc. Throughout this document common sense construction techniques should apply. Materials and joints should be flat, square and true.

1.1 Endplates

Endplates shall be constructed of 3/4 inch birch plywood or an equivalent material that resists warping
Endplates shall be 6 inches high and a minimum 12 inches wide.
A 24 inch width is recommended for ease of transportation and continuity with other modules. Any deviation from this recommended width would result in cosmetic misalignment of the fascia with other modules.
Avoid using dimensional lumber since it has a tendency to warp.
Module to module endplates shall be secured with C-clamps.

1.2 Legs & Bracing

Each module shall have legs that support the module free-standing.
Each leg must be vertically adjustable plus and minus 1 inch to compensate for uneven floors.
The bottoms of the legs shall have rubber tip or equivalent floor protection.
Nominal and minimum height of rail head from the floor shall be 50 inches.

1.3 Surface

Sub roadbed surface shall be sturdy enough to prevent sagging over the length of the module.

1.4 Fascia & Skirting

Each side of a module shall have a fascia that fully covers the side.
The top edge of the fascia shall be contoured to match the scenic topography of the module.
The fascia shall be painted a semi-gloss, satin or equivalent black color.
Both sides of a module shall have a black skirt.
Each end of the skirt shall extend past the module endplate to overlap with adjacent module skirting.
The bottom edge of the skirt shall be even with the bottom of the leg vertical member to prevent dragging on the floor.

2.0 Track

All track shall be code-55 or less, nickel-silver flex or hand laid, with prototypical tie dimensions and tie spacing. Hand-laid track shall have a minimum .030" flange clearance.
Minimum radius for all track shall be 22 inches with at least 6 inches of straight track between reverse curves.
All turnouts shall be at least #6.
The maximum grade on any track shall be 2.0 percent (1/4 inch per foot).
Graded modules shall return elevation to the nominal height of 50". Differing elevations must be coordinated with the local community or layout coordinators to ensure proper elevation accomodation is agreed upon.
Main line roadbed must be 1/8 inch cork or equivalent.
At the endplates, track shall cross on center or within the central third of the module's width. All track crossing the endplate shall be perpendicular, straight, and level for at least 4 inches from the outside face of the endplate.
Multiple track endplates shall use 1.125" spacing. When properly coordinated within your local community or layout coordinators, other spacing may be used to accomodate prototypical track arrangements, provided sufficent transitions that return track to 1.125" spacing or single track are available.
Multiple track spacing is measured from one reference point on one track to the same reference point on the adjacent track. Spacing and gauge shall be checked independently for each rail of each track. Validate all measurements at the endplate with a precison ruler or caliper.
Rail and track shall be cut flush with the outside face of the endplate.
Modules will connect at the endplates by clamping securely so that the rail-heads align without the use of rail joiners.

3.0 Wiring & Electrical

NMRA compatible digital command control (DCC) shall be used for layout control.
For larger multi-group shows, Digitrax systems shall be used unless alternative systems are agreed upon and can properly support all show operations.

3.2 Turnouts

Turnout frog, points and point rails shall be powered in a manner that does not rely solely on the contact between the points and the stock rails.

3.3 Main Line Track Bus

Track Bus wire shall be 14 gauge or heavier spanning the length of the module between the endplates.
Track feeder wires shall be 24 gauge or heavier.
The Track Bus wires shall terminate near the center of the end- plate(s), extending long enough to attach to the adjoining module, with a pair of 30 Amp Anderson Powerpole connectors stacked vertically (hood up, tongue down).
It is recommended that you use a pair of red connectors to distinguish them from those used for the Accessory bus.
The top connector shall attach to the left rail, as you face the endplate, the bottom connector shall attach to the right rail.
Applications that require an AC or DCC signal may utilize power directly from the bus.

3.4 Accessory Power Bus

AC Accessory Bus wire shall be 14 gauge or heavier spanning the length of the module between the endplates.
Accessory Bus wires shall terminate near the center of the endplate(s), extending long enough to attach to the adjoining module, with a pair of 30 Amp Anderson Powerpole connectors stacked horizontally (tongue-to-tongue, hood-to-hood).
It is recommended that you use a pair of black connectors to distinguish them from those used for the track bus.
This two wire bus is used to power turnout motors that control track switches but it may also be used to power other accessories on modules such as structure lighting, signals, animation, and the like. It normally carries a DCC signal similar to that found on the Track Power bus (a separate booster is recommended to avoid robbing power from trains); however it may carry 16V AC as an alternate, lower cost implementation (but less flexible). Electrical accessories within modules can use the DCC power directly (e.g. to control and power stationary decoders), or rectify and regulate it to DC (e.g. to power lights or electronics). If 16V AC is on this bus it may be used directly or may be rectified and regulated to DC as well. One solution is to use a bridge rectifier like Radio Shack's 276-1146.

3.5 Network Bus

Each module shall provide means to bridge a network bus between adjacent modules. Internally mounted network bus shall be terminated within 6 inches of each endplate using a 6-wire "RJ12" single plug jack mounted on the underside, and include a 12" cable jumper to bridge adjacent modules. External network bus may be used to bypass entire modules or module groups that do not use network components..
Inter-module connection is achieved with a simple 6-wire RJ12 cord. All of the network bus connections require straight-through cables. Standard telephone cables are not wired straight through. Use color-coded wire matching the wire colors present in the phone jacks (white/green/yellow/black/red/blue is most common). Use minimum 26 ga. solid core wire for sturdy connection to phone jack screw terminals. Add strain relief to the wires near their connections to the phone jacks.
Throttle tether panels and network components are allowed on any module.

4.0 Scenery

Main line shall be ballasted with a fine light gray material and some form of scenery hiding the bench work.
Scenery for the first 6 inches at the endplates shall have a flat profile roughly 1/4 inch below the top of the main line rail.
Landscaping along the module ends must be designed to flow smoothly into adjacent modules - avoid features such as roads, lakes, and so forth from running against the module ends. Use a generic grassy/sandy terrain. Avoid structures and other details that could obstruct your forearms.

5.0 Equipment

Rolling stock wheels, trucks and weight shall meet or exceed NMRA Standards and Recommended Practices.

6.0 Miscellaneous

6.1 Crowd Control Barrier System

Each 8-foot length of module should have one barrier stand per side. A crowd control barrier system consists of stands and ropes. Ropes are 1/4 inch yellow nylon style (available at any hardware store). Stands consist of a base and upright designed for simple construction and setup, and which may be separated for efficient storage and transport. Stand bases are 12” square made from 1” plywood (or equivalent multiple plywood layers). Painting is optional. A hole is centered in the base to accommodate a 1/2 inch white PVC pipe end cap, used to receive the stand upright. Stand uprights press-fit into the base and are 36” tall 1/2 inch white PVC pipe with a PVC “T-junction” mounted on top, through which the nylon rope is threaded. Painting is not allowed - leave uprights white.

Revision History

  • Rev 1, 14 Aug 2002, Initial Revision, created by Wesley Steiner.
  • Rev 2, 12 Sep 2002, Upgraded track bus wiring minimums to meet DCC requirements.
  • Rev 3, 30 Jul 2003, Increased feeder wire minimum from 22 to 24 gauge. Increased rail setback from 1/2" to 3/4".
  • Rev 4, 08 Nov 2005, Powered frogs. Simplification and clarification. Anderson PowerPole bus connectors.
  • Rev 5, 01 Aug 2010, Reformat as a PDF file and fix spelling errors.
  • Rev 6, 02 Jul 2011, Replace rail set-back with “butt” joints.
  • Rev 6.1, 31 Jan 2021, Spelling errors and formatting.
  • Rev 6.2, 12 October 2021, Formatting and section numbering.
  • Rev 7, 10 May 2022, Track Clarfications, Double Track Practices, Optional Panels.