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Club oNeTRAK Standards

Bantrak oNeTRAK standards are currently undergoing revision

one track module

What is oNeTRAK?

As defined by NTRAK, oNeTRAK is an NTRAK compatible single-track branch line that can augment NTRAK layouts.

BANTRAK oNeTRAK Group (BOG) Module Standards

Bantrak oNeTRAK standards are undergoing revision as of May 2018


The oNeTRAK module system is based on the NTRAK module system, but using one rather than three main tracks to more accurately represent typical North American Railroading.


Baltimore oNeTRAK Group (BOG)

The Baltimore oNeTRAK Group (BOG) is composed of members of the Baltimore Area NTRAK Club (BANTRAK) who are interested in using oNeTRAK to simulate a branch line that will highlight more realistic operations, DCC train handling and a higher degree of craftsmanship than is currently found on the group’s NTRAK layout.  BOG is affiliated with BANTRAK but is a separate entity;  while it can operate in conjunction with BANTRAK, it is designed to operate independently and not draw on the resources of BANTRAK.


Design Philosophy

The interest of the group is to develop a group of modules with a common design theme that fit together scenically.  The BOG layout will represent a branch line (Appalachian branch) of a fictional regional railroad (Baltimore & Western) that stretches from Baltimore to the Ohio river.  The modules of the layout will consist of scenes that could realistically be found along that line.  Module scenery will reflect a late summer (August/September) season, and foliage and ground cover colors should reflect this.  The layout will be set in present day (2006), but the scenery should be as “era neutral” as possible to enable other eras to be simulated on occasion.


  1. Light weight, simple to build modules, especially for beginners or those with limited transport capability.

  2. Provide an alternative to three track modules that can be connected to an NTRAK layout.

  3. Provide an easy way to model scenes with single track and tighter curves.

  4. Provide a more prototypical operation which will involve main line and switching duties.

  5. A system that will allow different formations of modules and will allow easy expansion without having to alter anything already done.


  1. Items in black below are the current oNeTRAK standard (Version 1.01 - 25 March 2001).

  2. Items in green are the proposed BOG standard; either an addition to the oNeTRAK standard, or a replacement for anything marked in red.

  3. Items in blue marked as [RP] are the BOG Recommended Practice;  the oNeTRAK standards still applies, but the BOG RP is the preferred option.


1.  HEIGHT OF TRACK – Nominal height is 40 inches. To make grades longer than one module the module interfaces on grades may need to be changed from the 40” standard height.

2.  FRAME SIZES – Frame lengths are in multiples of one foot. Twelve inches is the minimum width; this width may be increased up by another one foot, front or back for a total maximum width of three feet.

[RP] Preferred module width is one foot (12”).

[RP] Preferred length of straight modules is 4 feet.

3. MODULE INTERFACE – Similar to NTRAK with two clamps and a 3 inch section of Atlas Code 55 sectional track.  To accommodate this, track should end 1.5 inches from the end of the baseboard using a 1.5 inch piece of Atlas Code 55 sectional track or a BOG provided template as a guide.  The frame on the module end is 1x3 or 1x4 timber or plywood equivalent.  Modules are joined in a layout by clamping with two "C" clamps, one at the front and one at the back of the modules and inserting a 3 inch section of Atlas Code 55 track.  Module owners are required to furnish two 3 inch C clamps for each module.  For connections between a dedicated pair of modules you may use other standard Atlas Code 55 sectional pieces.

4. TRACK – Atlas Code 55 track is the standard.  PECO and Micro-Engineering Code 55 track are acceptable alternatives.  Code 80 track should only be used on parts of a module that are designed to interface with an NTRAK layout.  One track is required, additional through tracks are permitted.

5. MINIMUM RADIUS - Is 18 inches with appropriate easements.  To prevent binding the minimum length of tangent between all reverse curves must be 7 inches.

6. LOCATION OF TRACK – On straight modules the location of the main has no impact on the loop of modules and is not important, but generally the track is set back 4 to 6 inches from the nominal front so that the Fascia may be reasonably aligned. Bump outs on the module are permitted, same as NTRAK.  Double or triple track should have 1.5 inch center spacing at the module interface.

[RP] Recommended location for the main line for modules with a single track is 6” back from the nominal front of the module (i.e. in the center of a standard 12’ wide module) to facilitate flipping the modules.

[RP] Closer spacing of 1-1/4 inch is acceptable between dedicated module sets and within the module as long as clearance for equipment is maintained. Minimum radius for track offset should be observed.

7. CORNERS - Standard corners can be 3 by 3 or 4 by 4 feet, etc.  On a standard comer the track should be set back 6 inches from the nominal front edge.  This makes layout design with inside corners easier.  With track set in 6” modules can be used as inside or outside corners and maintain the one foot spacing increments.  30 by 30 inch corners are also acceptable.  On a 30 by 30 inch comer there is ample room for the 18 inch radius curve and easements.

[RP] Custom corners may use alternate track placement between 2 and 6 inches from “front”.  Alternate track placement will determine “front” of module meaning the module will become either a dedicated outside or inside corner.

8. CLOSING LOOP LAYOUTS - Due to the wide variety of frame sizes and locations of tracks, some gaps may develop in a loop layout.  Most large loops should be flexible enough to close a gap by "scrunching" the modules together.  In some cases a temporary bridge may be necessary.  This can be made by using a piece of foam, some flex track, and a bar clamp to close the gap.

9. JUNCTIONS - The smallest recommended junction is 3 by 5 feet.

10. GRADES – A 2 percent maximum across a dedicated set of modules.  Grades on other modules can be created with shims under legs of modules. Grades suggest addition of a helper district and helper engine facility.

11. END TURNS are modules that include a 180-degree curve in the track.  They should be a minimum of 2 by 4 feet to allow the 18-inch minimum radius and easements.  The distance between the ends of tracks on an end turn must be three feet or more in even foot increments.

12. TURNOUT SIZES - All turnouts should be largest available on the mains, crossovers, passing sidings and interchange tracks, with a #7 being the minimum size used at any switch where the mainline follows the diverging route.  Smaller turnouts are allowed for industrial sidings where through trains will not following the diverging route.

13. ELECTRICAL – Three electrical supplies are required on each module.  Low voltage track and power supply cables should be permanently attached to module at approximately 6 inches from “front” and within the framework.  Each cable should be long enough to include “tail” that extends 6 inches below the clamping area of the module.

  1. Mainline wire: 12 gauge unbroken stranded wire running the length of the module.  6” tails on each end with Powerpole connectors. Follow NTRAK Powerpole RP using red line color code and assembly practices.

  2. A 12 gauge DCC accessory supply cable running the length of each module with 6 inch tails.  Connectors configured in the “track bus” stacked arrangement and marked with purple tape or appropriate purple/black Powerpole housings.  Colored housing will be designated Rail A, Black housing designated Rail B. DCC accessory decoders should be connected to this bus.

  3. 14-16 v AC accessory power cable running the length of each module.  Color code for this cable is Brown.  Powerpole arrangement is “side by side” as in NTRAK specifications for the white line. 6 inch tails are recommended.  Connection of accessories to the bus should be of an easily removable type. E.g. Switch, plug, or Y cable.  This will allow easy disconnect of a malfunctioning accessory without disruption to the bus.

BOG oNeTRAK modules will be Powerpole equipped only.  Adaptors for Powepole to Cinch-Jones connectors will be needed only if being used with non-Powerpole modules.

Follow NTRAK standard practices for module wiring.  Track feeders should be located every two feet starting 12 inches from module end. Additional feeders should be attached to any rail that is not soldered to a rail that has a feeder attached.  Do not depend on rail joiners.

A feeder should be attached to each stock rail of a turnout.  Atlas code 55 turnouts have live frogs and a means of feeding power to the frog via a switch is recommended.

Turnout motors can be used.  A separate power supply and operating controls should be mounted on the module.  DCC accessory decoders may be used. Decoders should be of a type that will allow pushbutton control as well as throttle control.  Do not connect DCC accessories to the DCC track bus (Red Line).  The separate Purple DCC accessory bus will be used for accessory decoders requiring a track connection. This allows operation of decoders while the main track power is down.

We will use Anderson Power Poles (30 amp rated) for connecting the various common wiring.  These will be color coded to match the color convention used to identify the wiring.  Length of tails should be set at 6” below the bottom of the module clamping surface.  NTRAK Recommended Practices for Powerpoles and 12 gauge wiring will be standard.

Since oNeTRAK modules are reversible, owner will need to designate a “Front” side of each module.  This should be marked on inside of framework visible to those working under the module.  All wiring should be done using the designated “Front” as reference.  Powerpoles allow for module reversal so adapters will not be needed.

14. SCENERY - Scenery should reflect that found typically in the Mid-Atlantic region (PA, MD, VA, WV) along the route of the fictional railroad. Modules featuring prototype locations are encouraged.

  • Era – The default era is present day (2006).  Scenery should be “era neutral” if possible, with signs and billboards appropriate to a wide timeframe and vehicles being removable, to allow maximum flexibility in layout design and operation.

  • Scenery Colors – Foliage and ground cover colors should reflect a “late summer” (August/September) timeframe, featuring colors like light green, yellow grass, burnt grass (Woodland Scenics), and late summer (Scenic Express).  Dark and bright green should be avoided, except in specialized areas. Snow is prohibited.  The majority of trees should still be green, but a smaller percentage may have changed to fall colors (yellow, red, orange, or brown) to simulate “stressed” trees or early changers.

  • Ballast – Ballast for the main line will Woodland Scenics Gray Blend Fine Ballast (B1393).  Sidings should use either the standard mainline ballast, or ballast appropriate for the industry being serviced.

  • All track will be painted a weathered track color (no shiny rails or plastic sleepers).  Rail brown is the preferred color, but other colors are acceptable as long as they blend well.

  • Round down hills on the ends of modules so the view from an adjacent flat module looks like scenery.

  • All fascia, module frames (including ends) and legs will be painted flat black as per BANTRAK standard.  Fascia will include a continuous strip of Velcro for hanging skirting.

  • Skirting – Skirting is not required for modules using standard legs (see 21).  If used, skirting will be BANTRAK standard “Girl Scout Green” cloth.   Skirt should be length of module plus any additional depth over the standard 12 inch width plus 6 inches to overlap skirt of adjacent module. Skirt should be 38 inches tall, and hemmed at top and bottom to prevent fraying.  Velcro hooks should be attached (sewn preferred) to top of skirt.  Velcro loops should be attached to module at top edge using glue/and or staples.

  • Do not use diorama dividers.

15. SKYLINE - Sky boards or vertical scenery flats are optional.  In many cases photography is easier if the skyboard is removable.

[RP] Skyboards are not required, and are in fact discouraged.  If at all possible, modules should be designed to be viewed from both sides.

16. PASSING SIDINGS - To enhance operations most or some layouts should include several passing sidings.  Clubs should try to include one or more standard passing sidings in a layout.  A standard passing siding is a set of two 1 by 4 feet modules with turnouts at each end of the pair and double track connecting the turnouts.  The resulting passing siding is about seven feet long.  Double or triple track modules can be used to extend these sidings.  Passing sidings and sidings should be double gapped and fed with separate feeders.  Do not use power routing feature of turnouts.  Addition of a toggle switch to turn siding on/off is recommended but not required.

17. OFFSET MODULES - Provide track offsets in one foot increments for visual variety.  Observe 18 inch minimum radius and tangent track between reverse curves standards.

18. OPERATIONS SCHEME - Although a stated purpose of our standards is to provide a venue for more prototypical operations, no operational scheme is specified.  Clubs and individuals can tailor their operating scheme to their situation.  To increase the potential for realistic operations, wireless DCC is recommended.

19. LAYOUT DESIGN – oNeTRAK modules have proven very flexible in layout design both as part of an NTRAK layout or when standing alone.  Note that Ntrak modules can be used in a oNeTRAK layout.

20. DCC SYSTEM - We will use Digitrax as our main DCC system.  All DCC components where possible will also be Digitrax for compatibility reasons and experience.

21. LEGS – To present a quality appearance, all regular modules will use a standardized “trestle” leg design;  modules using the trestle legs will not require skirting.  A set of legs will be positioned 12” in from each end of the module, with modules in excess of 5’ in length having an additional set installed in the middle of the module.  Non-standard or irregularly shaped modules may use other legs systems designed especially for those modules;  however these modules will be required to have skirting as specified in (14) above.


Trestle Leg Construction

trestle leg view

by Tim Nixon

  1. Trestle legs are made from a 2x3 (actual dimensions are 1.5” by 2.5”).

  2. Using an 8’ 2x3, cut three pieces from it; one 32” long, one 34” long and one equal to the interior module width (for a 12” module this is 10.5”). For those keeping track, that’s 76.5” of a 96” 2x3.

  3. Rip the 32” and 34” pieces in half on the long dimension (1.5” by 1.25”). I then cut a 12” piece and an 18” piece out of one of the 32” pieces, and cut 5-degree angles on the ends of the 34” pieces. This gives me one 32” piece, one 12” piece, one 18” piece, two 33” angled pieces, a 10.5” full size piece and some leftovers.

  4. The 12” piece is the top, the 18” piece the bottom, and the 32” piece the center member. The angled pieces need to be cut to fit, actual length needed is about 32.25”. The 10.5” piece is screwed in under the module to act as a guide for the gusset plates.

  5. Cut some gusset plates out of plywood; there are the width of the module and about 6” deep (12x6 in my case). These screw onto the top of the leg assemblies, with about 3” about the top piece, and 3” below and onto the legs. Cross braces on the legs (for show) and diagonals between the legs are also cut from plywood; they are about an inch wide, and 3-4’ long.

  6. Put the legs together with 1-5/8” wood (deck) screws, at this point, don't bother with glue.

  7. Drill holes in the center post for a wooden dowel to hold the diagonal bracing; the holes at 4” from either end, which makes them 24” apart; the same spacing as the legs. A bolt could be used instead of the dowel, a bolt would make for a tighter connection, as right now the diagonals are just press-fit on the dowels and can slip off.

  8. Finally, drill two holes in the base and install t-nuts and carriage bolts for leveler feet.

For those doing math; the height of the assembly plus module off the floor is:  1.25 (bottom) + 32 (centerpiece) + 1.25 (top) + 3.5 (frame) + 0.5 (plywood, cork, track) = 38.5” Which means you need a 2.5” carriage bolt to cover the 39”-41” above the floor height range requirement.

If you have any questions or comments on the legs, let me know.


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