Headwaters HOtrak Module Group Specifications

Last Modified On: Friday, February 09, 2001

These specifications and plans describe the standards used in constructing HO modules by the Headwaters HOTrak Module Group (HHMG). They are designed to provide an introduction to modular railroading for the beginner, as well as provide the standards which are used by the HHMG.

The purpose of these standards are to ensure:

1.) Compatibility between different members' modules.

2.) Trouble free operation of the assembled layout as a whole.

3.) A uniform appearance, so the modules look like they belong together.

One of the advantages of modular railroading is to allow each member to 'personalize' their own module(s). To that end, variations on these specifications are allowed to provide for creativity and to provide for night, bad weather and winter themes. Please discuss any variations with the general group to help discord.

The HHMG recommends the late 1950's steam/diesel transition era because most equipment will not look out of place in that time period. However, the setting for your module is entirely up to you,it can be modern or historic, urban or rural, mountains or desert, etc. There are a few standards regarding backdrop color, etc., which are listing on the Data Sheet, but otherwise almost anything goes. In particular, terrain which goes below the track level to allow bridges, trestles, etc. is permitted (even encouraged), but any cutting or modification of the module framework should first be peer reviewed by the module group to ensure structural integrity.

Tunnels on the mainline are discouraged - remember that many of our members run modern equipment with 3 level auto-racks and double stack containers, so any tunnels MUST have adequate clearance.

A couple of things to think about in designing the scene for your module: First of all, since the primary purpose of these modules is to be on public display, any eye-catching or humorous elements in the scene on your module are a plus, particularly things which imply activity other than the trains moving through the scene.

Another thing to consider is that your module is going to be subjected to rougher treatment than your layout at home, no matter how tenderly and carefully you treat it. This means that your scenery must be even more solid in its construction. Buildings, and especially figures, must be anchored down much more solidly than you would on your home layout (some people even make the buildings on their layouts removable, and carry them separately when transporting their modules). Any kind of mechanical animation on a module is a real crowd pleaser, but transporting it can throw it out of whack before you know it. If you want to have something like that, consider making it removable so that you can transport it separately (not to mention being able to perform maintenance on it if something does go wrong).


Please remember that while individual creativity and craftsmanship are encouraged in building your module, when these modules are out on display for the public, their purpose is to provide an entertaining display with continuous operating trains. If there is some element of a module which interferes with the operation of the trains, especially if it is something that is a departure from these standards, then any necessary corrective action to get the show 'back on track' will be taken, Such action may include (at the module coordinator's discretion): repair of the problem (if it can be done quickly), removal of whatever is causing the problem from the module (for example, removing a bad turnout and replacing it with a length of flex-track), or removing the entire module from the layout. Please keep this in mind when designing and building your module(s).



A. Track power is carried under modules using these minimum figures. HO 18 ga. Two conductor recommended for neatness.

B. Track feed lines shall be firmly attached to each module and shall terminate at each end in a terminal block. Interconnect lines to track shall be as prescribed above. Terminal blocks will have connection to rail and connection to other module end, and may be a 2 pin Cinch-Jones (TRW#P302 & S302) or Radio Shack plug (#274-201 & 274-202). 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. (O scale modules shall use a 4 pin Cinch-Jones (TRW#P304 & S304 or Radio Shack #274-204 & #274-205) plug with pins 1 & 3 connected to the outside rail & pins 2 & 4 connected to the inside rail.

NOTE: Cinch-Jones and Radio Shack Connectors ARE COMPATIBLE.


 When track power connectors are used, the female connector is located at the left Interface (from the public viewing side). The male connector at the right interface (from same viewing side) is wired to the terminal block using an 18" length of flexible 16ga 2 conductor stranded cable. Track power connectors should be paired with color coding as follows: Outside mainline RED; center or inside mainline (on 2 track modules) YELLOW; inside or 3rd track BLUE; counted from outside viewing edge of module. 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.


Insulating material shall be used to fill rail gaps. No air gaps are allowed. Crossovers between mainlines and tracks leading from mainlines to other trackage on the module shall have both rails gapped (insulated). All tracks gapped for block control shall have both rails gapped (insulated).


Electrical Standard S-9 shall be observed.

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.



Recommended Practices are only less mandatory than Standards by virtue of their slightly less critical subject matter and/or the fact that deviation for specific reason is permissible.

A. 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.

B. Modular layouts may be easily divided into control blocks for multi-train operations. Blocks will normally be used to control trains on your own module or group of modules. To insert a block, place insulated rail joiners at one end of each bridge track and unplug the connectors at each end of break.

C. Block control of mainlines must be approved by all module participants.

NOTE: Common rail is NOT compatible with NTRAK wiring specifications. Check the S.I.G. for your particular scale for further details.

Use #22 to #24 ga 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 three 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 three main tracks are part of a yard, it must be possible to isolate them electrically.

Use UL approved heavy duty, multi outlet, extension unit with a grounded (three wire) power cord, 14 ga 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 winng, or any stricter local codes.

NOTE: For safety, a GFI (Ground Fault interrupter) circuit breaker is recommended in the 110 line powering a layout.



A. Peer Review

- All module designs are subject to peer review and approval by the club membership before construction. Peer review is intended to provide constructive suggestions, helping new module builders avoid the problems others have already overcome.

- Module designs presented for peer review must be accurate. The use of track planning software such as XTrkCad is recommended, as it permits plans to be shared electronically.



A. Height

- 50inches from the floor to the top of the rail.

- Height measured with leveler bolt threaded in.

B. Width

- 30 inches recommended at module interfaces.

- Oversized modules are permissible, but front or back extensions must be tapered to meet adjoining modules.

- Oversized modules may be dropped from a show if they cause problems with hidden staging yards clamped to the rear of modules or if extensions crowd aisles.

C. Length

- Straight modules:

Standard is 48 inches with optional lengths of 48" 72" and 96".

- Corner modules:



A. Materials

- Open to member's discretion.

- Tip: Recommended to use Robertson #6 wood screws.

- Tip: Lepage "Sure Grip" yellow glue is recommended as it works well on both wood and foam (Liquid Nails works well also).

- Tip: A hot soldering iron inserted into foam insulation creates 1/2" diameter holes suitable for wiring to structure lighting.

B. Suggested Design

- Open to member's discretion.

- Use lightweight materials as much as possible.

- Modules MUST be designed to set up and take down quickly.

- Tip: Before designing the frame, members are asked to discuss their module's construction with club members - we've got specialized tools, jigs, and experience that could make things go much smoother.

C. Exterior Frame

- Frame at module interface must be made of 1" x 4" (nominal, 1" x 3.5" actual) lumber at a minimum to permit module mating. Deeper framing on the ends is permissible but should have notches for mating with standard 1" x 4" module ends.

- Tip: Semi-circular notches are much stronger than square notches.

- Members are encouraged to use 3/4" plywood on the front and rear fascias and to contour the top edge of the front fascia so that it is not straight and level.

- Tip: It is suggested to get more room under the module for electrical equipment using true 1x4 or greater framing by ripping 1x5 or 1x6 or plywood sheet lumber down to true 1x4.

- Fascia of modules must be painted flat black.

- Tip: Affix a strip of Masonite (coarse side out) on the inside of the 30" end frame so that the clamps don't crush the wood.

- Tip: To ensure that pairs of modules supplied by the same member join perfectly, it is recommended that you use T-nuts to align the two modules. During construction, clamp the two modules together then drill two holes through the two interfaces just big enough for a 5/16" carriage bolt. Put 5/16" T-nuts on the inside of one module. Cut the heads off two carriage bolts leaving 1" of smooth shaft screw. With the two modules separated, screw the cut-down bolts into the T-nuts and then attach the other module.

- Tip: When building a pair of modules, temporarily cover the outside of the frame with masking tape so that scenery materials and adhesives don't adhere to the frame. Leave the tape 1/2" above the side frames so that scenery doesn't have to be cut on the interface (it also holds it in place). You should also build the modules as one block with the tape separating the scenery material. Lay the track in one continuous stretch and then cut the track at the joint afterwards. Connect with rail-joiners.

- Tip: Casters may be mounted on the gussets (ensure that you leave room for the legs) for easier transportation and so that other module pairs can be loaded on top of a "casterized" module. Module may have to be strengthened to carry additional weight of other module pairs.

D. Deck

- Modules must have a complete top deck (i.e. no gaps in the benchwork open to the floor).

- Deck construction is open to member's discretion, but to minimize weight, 1" or 2" extruded polystyrene board (NOT the beaded polystyrene board) is recommended.

E. Legs

- Module legs should be made of 2" x 2" (nominal) lumber.

- Modules must have a leveling mechanism that allows a variance of 2 inches.

- It is recommended that the bottom of leg have a 5/16" leveler using a T-nut in the bottom of the leg and a either a Madico brand leveler pad or a Lee Valley swivel glide which won't damage the floor.

- It is recommended that the top of the leg have a 5/16" hanger screw/bolt to connect into a 5/16" T-nut in the gusset in the corner of the module. This provides a very quick and easy way to attach/remove legs. T-nuts should be mounted from the top of the gusset.

- It is highly recommended that T-nuts be bonded to the gusset with contact cement or epoxy to prevent undesired removal.

- Legs must be painted flat black.

- Leg tops or bottoms should be marked to easily signify the owner.

- Tip: Railing balusters are often inexpensive and the right dimensions.

- Tip: Cutting an automobile inner-tube into circular strips provides a good strap for bundling 8 legs for storage. Short bungee cords also work well.

F. Backdrop

- A backdrop panel (sky board) is mandatory on all modules and must be positioned such that the top is 12" measured from the top of the rail to the top of the backdrop (approximately 16" total in height).

- Backdrops on canyon modules may be deeper than 12" but must still meet the 7.75" above the rails height for the top edge.

- Recommend use of 1/8" Masonite or Doorskin, smooth side towards public.

- At a minimum, the front of the backdrop must be painted with horizon blue paint which is provided by the club. Night, bad weather, winter colouring is permissible. Please coordinate with the group to minize discord among the modules.

- Rear is colonial blue paint provided by the club (Benjamin Moore paint using 305-4A base with the following shots/gal for each UTC: 30 OY, 2x28 BK, 2x8 BB and 24 GY).

- Top edge of the backdrop must be finished with white plastic panel-edge molding finishing.

- For backdrops that can be moved to the front of the modules, there must be a 1" clearance between the bottom of the backdrop and the bottom of the rear fascia (to provide room for velcro strips).

G. Plexiglass

- A 3/16" or 1/4" plexiglass guard is mandatory on all modules and must be positioned such that the top edge of the plexiglass is 4" above the top of the rail.

- All edges of plexiglass must be smoothed so that children who run their hands on the plexiglass don't cut their hands.

- If you wish to have your name on your module, it should be located near the centre of each module section behind the plexiglass. The club will provide the sign in the standard format.

H. Velcro Strips

- Black velcro strips (hook portion) are mandatory and must be affixed with glue (contact cement is suggested) and/or staples.

- Located on 12" centres and runs along bottom of fascia frame (front and rear).

- Strips start at end of module with 3" strips and strips in between ends are 2" strips.

- Members with canyon modules must have velcro strips in the appropriate locations for their custom skirts.

I. Skirting

- Skirting will be flat black and purchased from the club.

- Skirt must have a 2" extra material at both ends to overlap with skirt of adjacent module.

- At the end of each skirt, the velcro must go on top, bottom, inside and outside for a good connection to the next roll.

- Members with canyon modules will be provided skirting material but they will be responsible for having the material tailored to the module.

- The club is responsible for 24" wide skirts for stub ended modules.



A. 110/120VAC Power

- A multiple-head extension cord or a power bar must be used with the first socket being no more than 5 inches in from the rear of the right side and the cord must extend at least 12 inches past the rear left end of the module.

- Cord/power bar must be easily reversible from one end to the other.

- Tip: Cord/powerbar and all turnout controls should be recessed so that they are flush with the side and bottom of the fascia so that they don't catch when loading into vehicles.

B. Track Wiring - Main Bus

- A standard 4-wire trailer harness must be located and oriented as illustrated below (white wire to the front of the module).

- When facing the front of the module the female connector is on the left and the male is on the right.

- Bus wire must be stranded 18 gauge or larger.

- Recommended that 4-wire trailer wire be used throughout the module for colour-code consistency (available by the metre at Canadian Tire).

C. Track Wiring - Feeders and Gaps

- Feeder wire must be 24 gauge or larger.

- All tracks must be wired live so that the DCC-equipped locomotives can run anywhere anytime.

- Turnouts: Feeders must face the points of turnouts, not the frog.

- Turnouts: Crossovers must be double gapped to prevent short circuits.

D. DCC - LocoNet

- Control signals are carried over RJ12 6-wire computer network cable (the LocoNet).

- RJ12 wire to extend 6" at each end of the module with a male RJ12 connector at each end mounted at the ends, 12" in from the front edge.

- Each member must also have one female/female gender-bender RJ12 connector for each module to connect each module to the adjacent module.

- Each group of modules must have at least one female RJ12 throttle connection on the front fascia and one female RJ12 on the rear fascia every 48 inches.

- Double face plates should be used rather than singles.

- Modules with areas of switching interest or complex trackwork or transitions from two track conventional main to single track Freemo mainline should have LocoNet faceplates front and back.

- As the modules are reversible, throttle jacks and switches must be accessible from both sides of the module.

- Modules 24" or less in length that do not meet the criteria for complex trackwork are not required to have RJ12 face plates but must pass Loconet wiring through the module.

- RJ12 face plates should be mounted flush with the surface of the fascia by routing out a depression for the face plate to fit into.

- The RJ12 network cable is wired in a daisy chain fashion from each component under the module.

E. Module Wiring Diagram



A. Type and Size

- Mainline Tracks 1 and 2 must be either code 83 or code 100.

- Members with modules having code 83 track must have:

two joiners - 3" code 83, and

two joiners - 6" code 83/100.

- Members with modules having code 100 track must have two 9" code 100 joiner sections.

- Joiner sections must NOT include rail-joiners. Rail-joiners are part of the module, not the joiner track section. Rail-joiners must slide completely under the rails at each end of the module for storage between setups.

- All tracks must be nickel-silver.

- 1/4" roadbed is compulsory on the mainline.

- All track and turnouts MUST perform reliably and meet NMRA standards. Non-compliant modules will be dropped from setups until they meet the standards.

- Tip: N-scale rail-joiners may work better on HO-scale code 83 track than code 83 rail-joiners

- 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.

B. Mainline Location

- The double track mainline that runs through each module MUST be located as indicated:

Track 1 is 2.5" in from the front edge at the module interface

Track 2 is 4.5" in from the front edge at the module interface

- Code 83 mainline tracks must start 1.5 inches in from the module interface while code 100 mainline tracks must start 4.5 inches in from the module interface. Leave room for joiner track (not required between adjacent modules owned by an individual).

- Mainline minimum curvature radius is 32". Mainline curves must have easements.

- Mainline tracks may deviate from 2.5" and 4.5" in from front edge over the length of a member's modules but easements and minimum radii of 32" must be adhered to.

- Tip: When laying mainline track to the module's edge, make the interface 1.5"/4.5" less 1/8" and then cut it back to the appropriate length at the first operating session (ie. better to be a bit less than 1.5"/4.5" than a bit more).

- Tip: When laying track, use a parallel track tool (MLR Mfg tool #479-5002) that maintains a constant 2" between the mainline rails.

C. Turnouts

- Turnouts between Tracks 1 and 2 must be a minimum of #6/long or larger.

- Turnouts from mainline tracks to branch lines must be minimum #5/medium or larger.

- Turnouts on branchlines are at the discretion of the member.

- Each 8 foot length of module or group of modules from a member must have at least one crossover between Tracks 1 and 2. These must be properly insulated. Direction of the crossover should be coordinated with the group to ensure a reasonable number are available in both directions.

- To avoid damage during setups and teardowns, the points of a turnout should be at least 3" from any joiner track section at the edge of a module.

D. Grades

- Mainline tracks shall be a uniform elevation with no grades.

E. Clearances

- Tunnels, bridges, etc. should exceed the NMRA Clearance Gauge (Mark IV) so that long and high modern cars do not have problems. Since the Mark IV is designed for straight track, greater allowance must be given on curves.

- Clearances must accept double stack cars and 90' cars.



A. Clamps

- Each member's modules must come with a minimum of two 2" C-clamps (or larger) for clamping to the adjacent module. You must be able to clamp to an adjacent standard module.

- Tip: Mount a small block on a cross-member under the module so that the clamps can be easily stored so that they are never forgotten.

B. Wiring

- All wiring (track power bus, LocoNet) must be permanently attached to the module to speed up setups. Since the power cord must be reversible, it should be detachable from the module, but must accompany it to all setups.

- To avoid damage during transportation, dangling wires should be secured by closeable hooks, etc.

C. End Plates

- Recommended for storing, carrying pairs of modules, one upside down on the other with the backdrop of one inside the plexiglass guard on the other.

- Recommended that end plates be painted a distinct colour for easy identification.

- Recommend 1/4" plywood cut to 16" x 24" with a handhold cut out of the centre.

- Tip: Building modules in mirror image pairs will facilitate the use of end plates, thereby decreasing storage space and setup time.

- Tip: Putting wheels on one end plate permits the pair of modules to be moved like a wheel barrow.

- Tip: Because of the tight clearances between the two modules, structures/scenery must be carefully arranged so that they do not contact each other when upside down on top of each other.



A. Construction

- Open to member's discretion, but extruded polystyrene foam board recommended for the scenery base to minimize weight.

- Telephone Poles are to be placed 4" from each end at approximate 8" spacing across module on North side of mainline tracks.

- Tip: Atlas telephone poles with the bases removed are recommended.

B. Module Interface

- Scenery at module interfaces must meet flush with the bottom edge of the cork roadbed.

C. Scenery Colors

- While there are no restrictions on what scenery members may model, it is recommended that whenever possible, members use the same type (relative coloring) of scenic material to reduce abrupt changes between modules. HHMG recommends the following two foliage colors:



- It is suggested that the each module contain a mix of these colors, and other foliage colors as appropriate. HHMG suggest the following to help minimize discord among module coloration:

Spring - liberal usage of the green, with minimum tan to add variety.

Summer - a mixture of green and tan, or green on moister areas and tan to simulate drier areas

Fall - generous use of the tan and minimum usage of green to add variety.

Winter - exclusive use of the tan and snow as appropriate.

Woodland Scenics Medium or Mixed Green coverages and Light Grey Fine Ballast are suggested.