NMRA MCR Division 2 Modular Model Railroad

Engineering Document


    Each module shall conform to the following specifications, and each module, when completed, must pass inspection and earn approval of the Modular Committee.
    While each module is to designed such that the public can view both sides, for purposes of this document there will be a side 1 and a side 2, as well as an A end and a B end. So that: when facing a long side of a module, Side 1 will be facing you, Side 2 is the rear. A end is to the left, B end to the right.

    a.) Modules shall be a minimum of 24" wide and a maximum of 36 inches wide, 48" long. From floor to top of mainline rail shall be 40", with 1" of adjustment allowed in leg. Track will end 4.5" from end of module to allow for standard 9" connector (bridge) track.
    b.) Legs should be 2"x2" or L-Girder construction with either 1/4" or 5/16" bolts in leg bottom for adjustment of 1", plus or minus; legs can be attached by way of slip-in boxes, bolts, hinges or cleated. Legs will fold or be removable for transport. Scenery items, buildings, etc, may be removable or fixed in place. Legs will be painted flat black.
    c.) Clamps _________________- will be provided, _____ per module to secure and attach each module to the next.
    d.) Side 1 and Side 2 fascia's will be 6" deep (from module level measured down) and may extend above module top as appropriate to the scenery. Fascia will be painted ______________ (specific brand and color code of paint).
    e.) Each Fascia will display "NMRA MidCentral Region Keystone Division" in a conspicuous and coordinated manner. Each fascia will display the builder(s) name.
    f.) It is suggested the underside of the modules be painted white - this is to aid in troubleshooting at a show.
    g.) The under side of the layout shall be hidden from spectators by use of a _____________ (curtain, black or dark green in color, fastened to the modules by--------velcro, hooks, _________)

    a.) HO Scale, HO Standard Gauge, 2 mainlines centered on the module, spaced 2 inches center to center on straight track, 2 1/2 inches on curved track. No grades on mainline, all curves will be built with easements. Other tracks on module are optional.
    b.) Track shall end 4.5" from end of module to allow for standard 9 inch bridge (connector) track. There will be a minimum of 3" of parallel mainline, measured form the bridge track connection, before any crossings, divergence, curves or crossings may be installed. Therefore, no switch, crossing, or curve may be installed closer than 7.5" to then end of a module.
    c.) Ballast on mainlines will be ___________________(brand, size, color). Ballast on secondary trackage may be ____________________. Ballast in yards will be black, #________ in size.
    d.) Track on mainline will be ______________________(brand)
    e.) Switches on mainline will be a minimum of #6, and brand___________
    f.) Minimum mainline radius shall be 32". Minimum industrial or secondary trackage may be 24"
    g.) All clearance and track shall meet NMRA specification as per the HO Track Gauge on the mainline and secondary trackage.
    h.) If uncoupler magnets are used on the mainlines, they should be the electromagnetic type. It is recommended that permanent magnets NOT be used on mainlines.

    a.) Each module will be equipped with 2 DCC walk around plugs, placed in the fascia, centered one on Side 1, one on Side 2. The DCC control bus will connect at each end of the module to the next via_______________.
    b.) Track feed lines shall be firmly attached to each module and shall terminate at each end in a terminal block. Terminal blocks will have connection to rail and connection to other module end, and may be a 2 pin Cinch-Jones (TRW#P302 & S302) These connectors will have the wide blade (pin 1) connected to the outside rail terminal and the narrow pin (pin 2) connected to the inside rail terminal. The track bus will be 2 wire, 14 gauge wire. Common Rail wiring is not permitted.


    When track power connectors are used, the female connector is located at the A end, the male connector at the B end is wired to the terminal block using an 18" length of flexible 14ga 2 conductor stranded cable. Track power connectors should be paired with color coding as follows: Side 1 mainline RED; Side 2 mainline. All electrical connections shall be soldered and taped or otherwise insulated. No section of mainlines or passing track shall depend on power being fed through bridge track.
    c.) There shall be no electrical gaps in the mainline. All secondary trackage will be electrically isolated from the mainline track (gaps in both rails, filled with plastic or other non-conductive material). The electrical connection from mainline to secondary trackage shall be done under the module and clearly marked so that it can be disconnected during a show if the need arises to trouble shoot an electrical malfunction.
    d.) (*)NOTE: The use of 110V power is acceptable provided all components carry UL labels and are secured to the underside on the module and measures taken to prohibit any possible connection to the low voltage wires. Local electrical requirements may vary at different locations so it is advisable to contact the local fire inspector for details. NO 110volt outlets are permitted on the fascia for safety reasons. Any outlets mounted under a module must be more than 8" in from an edge, again, for safety reasons. Connections between modules may be dune using 3 pronged wire of at least 14 gauge into an UL approved receptacle. Use UL approved heavy duty, multi outlet, extension unit with a grounded (three wire) power cord, 14 gauge wire, 15 amp capacity. Use Stanley 1-1/4" Safetycup Hooks #V8482 to retain cord. Unit must be removable to meet safety codes, Wiring is subject to inspection by safety officials at public gatherings. if built in, 110V wiring must meet National Electric Code for Temporary wiring, or any stricter local codes.

    NOTE: For safety, a GFI (Ground Fault interrupter) circuit breaker is recommended in the 110 line powering a layout.
    e.) Powering of local tracks, switch machines, building lights, etc., is the responsibility of the individual builder and should be separate from circuits which interface with other modules in a layout. Power cannot be taken from the mainline to power accessories. Power may be taken from the mainline to power secondary tracks.
    f.) Use #22 to #24 gauge solid wire soldered to the outside of rails for connection to track power leads. "Solder terminal Strips" make an easy to trouble shoot connection point. Use as many power feeds per tracks as needed.

    NOTE: A single large power supply is used with the many throttles on large layouts. The 2 mainline tracks MUST NOT have any common connection. DO NOT use "COMMON RAIL" wiring. Gaps must be used on both rails on any crossover tracks. If the 2 main tracks are part of a yard, it must be possible to isolate them electrically.

    a.) All trains shall be HO scale, DCC decoder equipped, and have Kadee or Kadee compatible couplers.
    b.) All cars shall be HO scale, have Kadee or Kadee compatible couplers and meet NMRA recommended practices for weight and rolling characteristics.

Scenery and Theme
    a.) All scenery shall represent the Western Pennsylvania area.
    b.) Module theme must be approved by the Modular Committee prior to construction and cannot be duplicated by another member.