All NMRA standards must be met.
Sub-roadbed construction and materials are free, but must be built to prevent sagging or flexing, and must be installed to comply with the endplate requirements (see section 3.0 "Frame Work"). Track MUST be perpendicular to the endplate both horizontally and vertically!
Material is free, but must comply with the 3/8" standard for top-of-scenery to rail-top dimension. See section 3.0.
Suggestion: Standard HO scale cork roadbed used under flex track meets the 3/8" requirement.
The mainline must cross the module end plate centered on the 24" width or centered 12" from either side of the 26" endplate for double track modules; it MUST be perpendicular to the endplates both horizontally and vertically! The mainline must run straight and level for at least 6" from each endplate. Otherwise its location is free (within limits of standards for curves and turnouts). This guideline ensures there is at least 12" of straight track between reverse curves. The mainline should run no closer than 6" to edge of free-form module
Rails end 1" from end of module (outer surface of the endplates). Ties and ballast continue to end of module. The ties within 1.25" (minimum) must accommodate installation of fitter rails with accompanying rail joiners, which are slid onto the module's fixed rail ends (typically these ties have a small "trench" where the spikes normally are found). Modules are connected with 2" fitter rails and rail joiners, which are dropped into the rail gaps and joined to the module rail ends.
All track must be nickel-silver commercial or hand laid. Mainline track must be Code 83. Other track may be smaller (e.g. Code 70 or 55), but must permit reliable travel by rolling stock with NMRA RP25 flanges. All active rails must be clean and flange ways clear. Paint sides of rail and tie plates with an appropriate colour. To reduce shine on plastic ties paint with Poly S or Modelflex Flat Finish.
Rail colour to be a mix of PollyScale, Acrylic Weathered Tie Brown and PollyScale Acrylic Engine Black in the following proportions:
1 fl. oz. (standard size bottle) W.T.B. 2 full eyedroppers (3" x 3/16) of E.B.
Clean rails and clear flangeways before each operating event.
Minimum radius is 42" for mainline, 36" for branch and industrial trackage. There must be at least 12" of straight track between reverse curves. All mainline curves should include easements; an article for creating easements can be found on the internet at http://www.trains.com/Content/Dynamic/Articles/000/000/001/647dsuww.asp
Even though we specify a minimum of 42", the use of a 48" or larger radius curve looks so much better. 36" radius curves will be permitted on mainline junction connecting tracks and on staging loops with 2 1/2 " track spacing.
Double tracks at a 26" double track endplate must be centered 2" apart, with each track centered at 1" from the endplate centerline (see drawing on Page 5). It is important that the 2" centre between tracks is maintained, and that one track be centred exactly 12" from one edge of the faceplate. This ensures that when connecting double track modules the tracks line up properly. If both tracks are measured from the edge of an endplate that is not exactly 26" wide, the 2" rail spacing could be compromised, creating problems matching with other modules. Rail tops of all tracks must be at the same height, extending perpendicular from the endplate face for a minimum of 6".
Some legacy module designs have more than one track at a 24"-wide endplate. In this case the single main line track must be centered on the endplate. Tracks adjacent to the centred main line must be centred at 2" from the main track to align properly with double track modules. Rail tops of all tracks must be at the same height, extending perpendicular from the endplate face for a minimum of 6 inches.
Super-elevation of mainline curves, vertical track curves, and grades are permitted, appropriate for mainline operation of contemporary long cars (90' cars must be able to negotiate these track profiles without derailing or uncoupling from adjacent cars). The maximum mainline grade is two percent (1/4" rise per foot of run). Track must be level for at least six inches from each end of module.
Suggestion: when constructing track that includes vertical curves as described above, use a straight edge of at least 12" laid on top of the rail to measure the rate of change of the rail height. Measure each rail separately. The space between rail top and straight edge should not exceed 1/16" within 12" of horizontal run.
Note: grades are possible within a large module, as long as nominal rail-top height is 50" from floor at both endplates of the module.
Minimum #6 for mainline but #8 is highly preferred. #8 turnouts are minimum for crossover turnouts between double mains on new modules. Minimum #5 for branch and industrial trackage. All mainline turnouts are controlled locally or through DCC. Point throw must reliably and completely close the point rails against the stock rails. Method of throw (powered or manual) is free. Tortoise switch machines can to be used as the powered devices for turnout control. If using turnouts for crossover purposes between the two mainlines, the switch machines MUST be interlocked to prevent incorrect alignment. When using powered switch machines the frogs must be power routed from stock rails (relying on the contact between point and stock rails to conduct power through points into the frog is to be avoided).
Note: DCC accessory decoders are allowed for turnout control as long as there is at least one other method available to throw the turnout (fascia buttons, hand throw, etc.). DCC decoder addresses must be registered with the set up coordinator so as to avoid any duplicate addresses.
All clearances (curves, tunnels, structures, etc.) must meet NMRA standards. It is recommended that if you constructing your own module that you purchase an NMRA HO track gauge to ensure that all clearances are met. Note: potentially every type of rolling stock will run over all modules; clearances must accommodate the tallest double stack, longest piggyback flat, etc.
All non mainline track, whether it be a branchline, industrial, interchange, etc.; can be of any reliable construction method using any track size equal to or less than code 83. All trackwork must be reliable and be able to operate the designated traffic it is constructed for.