Royersford Modular Model Railroaders

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40" 100 1-1/32" Horiz.
3" Vert.
5" 4.5" 2.0" 2.5" #6 or larger 12-16


100 1-1/32" Horiz.
3" Vert.
7" #6 or larger 12-16

(if used)

100 1-1/32" Horiz.
3" Vert.
9" #6 or larger 12-16


MAY VARY MAY VARY 1.5" or 4.5"
Other lengths are permissible on modules that are comprised of more than one section. These modules must be identified beforehand, so they can be placed properly into the display layout.
MAY VARY MAY VARY #4 or larger 12-16
  • Framing should balance strength with weight reduction, and may need to accommodate various design elements, so flexibility regarding the details of construction is left to the module builder.
  • The standard module is 24 inches from front to back, and 48 inches from left to right. Variations in these dimensions are permissible, but may restrict where the module is used in the layout, or whether it can be used at all during a particular show, depending on the configuration of the layout.
  • Recommended framing is 1x4 inch dimensional lumber for the front, back, and ends of the module, with additional bracing (usually 1x2) as needed.
  • Modules should be designed to use club-standard legs wherever possible. Any "special" legs required are to be marked as such, so that they can be paired with the proper modules during setup. Leg retainers should be attached to the inside front and inside back of the module, to allow each individual module to be freestanding. Connecting the modules together will ADD stability, but should not be a prerequisite to a module's stability.
  • Club-standard legs shall be constructed in pairs, with one leg of each pair sitting inside the front edge of the module, and one leg of each pair sitting inside the back edge of the module. Upper and lower crossbars shall connect the two legs in each pair. The top of the upper crossbar shall be no more than 3.5 inches from the top of the legs, to allow the end of the module to rest on the crossbar, while preventing the module's deck from hitting the top of the legs. Layout legs should be of a dark grey "backstage black" color, to avoid distraction from the scene presented at the surface of the module.
  • All module legs should have some means of height adjustment, to allow for unevenness in floor height. The recommended method is by the use of Tee Nuts inserted into the bottom of each leg, with carriage bolts threaded into these nuts to allow the module to be raised and lowered. Standard legs will use 5/16 inch diameter bolts (18 threads per inch - "coarse thread") of 3 inches in length.
  • Standard Plugs:
    TRW #P302 and #S302 OR
    Radio Shack #274-201 and #274-202
    ORcompatible substitutes from other sources.
  • Pin Assignments:
    Wide blade (pin 1) connects to outside rail,
    Narrow blade (pin 2) connects to inside rail.
  • As viewed from the front of the module:
    Female connectors are at the left end of the module.
    Male connectors are at the right end of the module, with 18" of cable (12-16 gauge wire.)
  • Color coding for plugs:
    Outside main track (track 1) - RED
    Second main track (track 2) - YELLOW
    Third main track (track 3) - (if used) - BLUE
    Other tracks - Label as needed.
  • Terminal blocks to be used at each end of module. Between connectors and terminal blocks, wire of 12-16 gauge is to be used. Between track and terminal block, wire of 22 or 24 gauge may be used. This lighter-gauge wire is easier to attach to the rails, and is acceptable for short-distance "feeder" wires.
  • For additional electrical guidelines,
    see NMRA Standard S-9.
  • Between wall plug(s) and transformer(s) a cord of sufficient capacity is required.
  • Use of surge protectors or spike arrestors is stronglyrecommended.
  • Additional precautions may be required by code, or by management of show venues.
  • In case of uncertainty in electrical practice, consult recognized resources and/or a qualified advisor.
  • Between module-end bridge track and first curve or track switch, a minimum of 3" straight track is recommmended.
  • Insulated rail joiners are required between all electrical blocks or sections, as "air gaps" are unreliable.
  • Curves (main lines) 32" radius minimum (standard)
  • Curves (branch lines) 24" radius minimum (standard)
  • Curves (industrial tracks) 18" radius minimum (recommended)
  • Clearance dimensions above are for main line tracks, to allow all types of rolling stock. On sidings, industrial tracks and spur tracks, clearance should be adequate for any cars that would reasonably be expected to use those tracks (e.g. double-stack cars are not expected to be sent to coal tipples.)
  • Modules shall be compatible with the use of DCC (Digital Command Control) as described in the applicable N.M.R.A. Standards.
  • Maintenance of any locomotives, switches, and other components equipped with DCC decoders, and of those DCC decoders, are the responsibility of the modeler to whom these components belong.
  • The installation of Universal Panels (UP-3, UP-5, or compatible items) on each module is not required, but is recommended, in order to provide reasonable opportunities for operators to plug in throttles.
  • The use of radio throttles is permitted, but operators should be aware of the location of the nearest Universal Panel (plug-in socket) in case radio contact is lost, and it becomes necessary to plug in the throttle to regain control of a locomotive. Stopping a runaway train by deliberately causing a short circuit across the running rails should be considered a last resort only.
  • On each module where a Universal Panel is installed, provision should be made for hanging a throttle while it is plugged into that socket. The recommended method is with the use of "hook-and-loop" tape; the "hook" side to be attached to the layout, and the "loop" side to be attached to the back of each throttle.
  • Skyboard height: 8" to 18" allowed. 12" recommended.
  • Details of individual module scenery are left to the builders of those modules, but generally should resemble other modules on the railroad in terms of season and geographic region.
  • Complete scenery is encouraged for all module builders. Incomplete modules should at least have some description attached, to let viewers know what is planned for those modules.
  • The front face of the module should be painted (or stained and varnished) to present a finished appearance. Earth-tone colors with a flat finish are recommended, but not required. Provision should be made for attaching signs identifying the club and each individual module.
  • Rolling stock (locomotives and cars) should be maintained in good condition, and will be subject to inspection before use on the railroad. Owners of cars and locomotives are responsible for the maintenance of that equipment, and for correcting any problems with that equipment. Equipment which does not operate reliably, or which causes interference with smooth operation of the layout may be rejected.
  • Rolling stock to be used on the railroad is to be painted and lettered before use on the railroad, especially during shows. (no "undec" equipment.) Weathering is optional, but recommended.
  • Each car and locomotive should have a unique number, to allow for operations, as well as reporting of problems with equipment.
  • Each car and locomotive is to be marked with the owner's name or initials, for identification purposes.
  • Trains should be operated at reasonable speeds.
  • Cars and locomotives within each train should be of similar era to maintain realistic trains.
  • All members and operators should keep a look out for any problems with any train, locomotive, or railroad car. Problems such as derailments, separated trains, or poorly-performing locomotives should be reported as soon as they are noticed.
  • All members and operators should keep a look out for any problems with track or scenery elements which interfere with operation of trains. Problems such as damaged switches, missing rail joiners, or scenic elements that have shifted in such a way that they interfere with operation should be reported as soon as they are noticed.
  • Damage to any car or locomotive must be reported to the owner of that equipment as soon as possible.
  • The location(s) of all incidents should be noted, so that track can be inspected and repaired as needed. Specific cars and locomotives involved in derailments should also be noted, so that they can be inspected and repaired as needed. Any car or locomotives which derails twice in the same day should be removed immediately for re-inspection before being returned to the railroad.
  • Coupling cars should be done at slow speed to avoid damaging equipment.
  • Any tracks which provide an opportunity for equipment to run off the edge of the layout (e.g. a siding which runs up to the back edge of a module) should have some type of blocking device installed to prevent equipment from rolling over the edge. Push-pins are allowed if no scale model bumpers are available, or appropriate to the specific location.
  • One of the club's goals is to educate visitors at our shows about the role, history, and importance of railroads in history and in the current world.
  • Club members should provide information as well as they are able. If the answer is not known, do not make one up. Ask another club member, or suggest an opportunity for further research.
  • Provision should be made for attaching signs identifying the club and each individual module. The recommended method is with the use of "hook-and-loop" tape; the "hook" side to be attached to the layout, and the "loop" side to be attached to the back of each sign.
  • C-clamps or bar clamps (recommended) or spring clamps (acceptable) shall be used to fasten modules together.
  • Adjustment screws at bottom of legs should be used to ensure that track surface can be made level, even when modules are set up on imperfect floors.
  • 9" connecting tracks (snap track or similar piece of track) are to be used to connect main line tracks on adjoining modules. Connecting tracks between other modules may be 9" long or 3" long. Connecting tracks are required, as rail alignment between modules cannot be guaranteed to be precise enough for reliable operations without any connecting tracks.
  • The front face (toward the public viewing aisle) of the module should be painted (or stained and varnished) to present a finished appearance. Finishing the rear face of the module is optional, but recommended.
    Provision should be made for attaching signs identifying the club and the individual modules.
  • Each module should be able to stand on its own legs, without needing to be attached to other modules to stay standing. This helps speed up the setup and breakdown of the layout, since some individuals can be setting up modules, while others attach them together and others adust and level them.
  • The layout should not be left unattended during shows. Members may take breaks, but should alternate these. Someone should always be on hand to answer visitors' questions, operate trains, and keep an eye on the layout, its contents, and its surroundings.
  • If the layout is left "set up" between shows in a venue, the control system should be shut off, the power supply disconnected, and all locomotives and throttles removed.
The standards on this sheet are those used by Royersford Modular Model Railroads, and while they are similar to, and generally compatible with, the N.M.R.A. modular standards, they are not identical.
You may print this page, and use these standards if you wish, but only you can determine if they are suitable for your needs or the needs of your group.
If you wish to follow the N.M.R.A. standards, please obtain a copy of those standards from the National Model Railroad Association directly, or from their authorized representatives.

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