Owing to our history as an NMRA group, our standards are based on guidance from the NMRA, as seen at https://www.nmra.org/introduction-layout-modules. As is often the case for NMRA-based module groups, our standards deviate somewhat from the original standards, for various reasons. Too, we seek to incorporate some newer concepts into our standards, such as those from Free-Mo.
Module width should be 24 inches at the end plate.
Module length as of currently is 48 inches in closed-loop setup.
We also have some 24 inch long modules.
Modules of non-standard size should have adapter modules to fill length to 48" (or 24"), or similar size module(s) for other side of loop.
Transitions to a loop-to-loop configuration are in the works.
Frame is typically constructed of 1x4 lumber.
1x6 or 1x8 lumber, or 3/4" plywood may also be used in entirety or combination as appropriate.
Lumber should be in good condition and free of bowing, twisting, cupping, and other warping.
1/2" BC style plywood should be used for the module top/subroadbed.
Foam (i.e. extruded polystyrene) may be used for the module top.
Roadbed and subroadbed should be square and perpendicular to the end plates.
Fascias must be smooth and made of a solid, sturdy material (plywood, hard board, Masonite, etc.) and should be cut to meet the profile of the module terrain.
Terrain should not be modified to meet a flat profile. 1 (In other words, fascia should be cut to fit the terrain, not the other way around.)
It is recommended that all controls be completely recessed in the fascia; non-recessed controls tend to get broken during transport and operation. (This goes for electrical plates, toggle switches, etc.) 1
Our current fascia color is a dark green, Krylon Fusion matte Spanish moss.
We generally don't use backdrops, owing in large part to our group's history as a youth layout. There may be applications where a backdrop would be appropriate, so there is also no prohibition on backdrops.
A module's leg pockets are mounted on the module frame at least 6 inches from the end plates of the module to allow space for connecting modules and their wiring.
Module height at the railhead is nominally 42 inches.
An inch at the top consists of track, roadbed, and 1/2" plywood (subroadbed), and a small gap to prevent the leg from impacting the module top.
Legs are typically cut to 40", with another inch at the bottom being comprised of an adjustable foot.
Current practice is using 2x2 legs, with pairs of legs joined into leg-sets by a pair of cross-bars mounted 3 3/8" from the top and 12" from the bottom (top edge measurements) on opposite sides.
Cross-bars are usually made using scrap 1x2, 1x3, or 1x4 lumber or similar size plywood.
Top crossbars should be installed toward the middle of the module, allowing space to run extension cords, or Loconet or other cables over them, and keep the floor tidy.
A shelf may optionally be used on the bottom crossbars for storage or other functions.
Individual legs may be used, but may require additional help in handling modules on setup.
Leg height adjustment should allow for the module to go up or down at least 1 inch.
We have used 1/4-20 threaded carriage bolt feet, mounted in a T nut at the bottom of the legs. This is still acceptable practice.
Current practice uses a 4" hex bolt, threaded through a 2" long piece of 2x2, with a nut-fender washer-soda cap-washer-lock washer-nut combination at the bottom, which makes adjustment from the top possible.
Other height adjustment systems are welcome, provided that they offer at least an inch of adjustment up or down.
A new option using 1x2's is currently under development, which can be extended up to a nominal 50" height at the railhead.2 It is intended for collaboration with Free-mo groups or other operational needs in the future.
Folding legs may also be an option, although we do not currently have any designs for them; consideration should be made for locking folding legs in place in either position.
We are currently researching alternatives to our existing skirting.
Main track center lines shall be 5 inches and 7 inches from the front of the module.
An alternative standard includes a siding centered at 2 inches from the front of the module, less roadbed.
Track shall end 1 1/2 inches from the end of the module to accommodate a 3 inch track section connecting to the next module. Module owners should have sufficient 3 inch track sections for each of their modules.
Due to compression from connecting bolts, 1 9/16" may be preferable. Further research is ongoing.
Original standards specified use of 9 inch track sections. A few legacy modules still use the 4 1/2 inch set-back, and 6 inch and 9 inch tracks will be available for connecting to these modules. Alternately, multiple 3 inch track sections can be used.
Roadbed laid underneath each main should continue to the end of the module, and should be painted a similar color to the ballast in case of ballast loss. Roadbed should also be painted near the end of the module where ballasting may not be possible.
We have used Midwest Products "HO scale" cork roadbed as the standard for roadbed.
Woodland Scenics foam roadbed and Walthers foam roadbed seem to have similar dimensions.
We have noticed that Life-Like cork roadbed (now out of production) is slightly taller than Midwest et al. Other roadbed types not listed here should be checked for similarity to our standard, however there is no prohibition on using other roadbed sizes.
Track on main lines shall be Code 100. Atlas nickel silver is preferred, but most code 100 track is compatible. Code 83 track may be used, as long as it properly connects to adjacent track.
Switch (aka "turnout") size should be as large as possible. Recent trackwork has included Walthers' new Code 100 switches. Peco turnouts may also be used, but care should be taken when using the old ElectroFrog style switches.
We have used Atlas track switches in the past, but more recently-produced Atlas switches seem to have declining reliability.
Large radius curves are preferable. Any curves of less than 24 inch radius should be avoided.
Rail joiners should be snug and sufficient to keep connecting rails in good alignment and electrical contact.
Bus wires should be installed for the length of the module. l We typically use 4-conductor trailer wire for our bus wires,3 but other bus wires may also be used.
From the module front, bus wire colors are white and brown for the front main line — and any additional tracks connected thereto — and yellow and green for the rear main line and connected tracks.
Track connections should be made no less than once per track on a single module.
Module bus wires should terminate at a terminal block.
Inter-module connections are made using 4-way flat trailer plugs,4 with the 3M1F (3 male/1 female) end at the right side of the module.
We use Digitrax DCC to power the layout. A Digitrax LNWI has been acquired for use with wireless devices as throttles.
We do not have any current standards for installation of UP-5 plug-in panels, but would suggest that any module with a track switch contain a UP-5.
We are considering making some short modules to serve as dedicated plug-in modules.
Two holes should be drilled in the end plates with a 5/16" brad point bit 6" and 18" from each side and 2 1/2" from the top of the roadbed.
For further clarification, the front hole should be between the track centerlines, and the rear hole 12" from the front hole.
A 1/4-20 tee nut shall be inserted in the hole at the right of the end plate, from the inside.
Adhesive and/or a small wood screw for keeping the tee nut in place are suggested, but not necessary.
We are experimenting with threaded inserts as an upgrade to tee nuts.
Modules are connected using 1/4-20x1 1/2" hex head bolts, with a fender washer.
Module bolts should be tightened using a ratchet, NOT power tools.
When disconnecting modules, it is our practice to return the bolt and washer to the same tee nut from which it was removed, but on the inside of the module.
Due to older modules' doubled-up end plates, longer bolts may occasionally be necessary.
