Draft of proposed Nn3 oNeTRAK Specifications 
for San Jose 2000 Nn3 layout

These draft specifications are based on the Draft oNeTRAK SPECIFICATIONS as prepared by NVNTRAK. They have been modified to suit Nn3 operations based on the work of the Nn3 special interest group in NTRAK. Also, see the "Nn3 Module Standards Drawing" shown above. The Nn3 Layout at San Jose 2000 will be the test of these standards, and they will remain as "Draft" pending evaluation of our experience using them in San Jose. Since San Jose in 2000 this has become the defacto standard even though there has been no definitive discussion to make it the way to go. Widths have changed so that 18 inch wide modules are acceptable and One Track does not have to remain square unless you are wishing a closed loop rather than point to point opeation.

The NVNTRAK oNeTRAK Specifications for standard gauge N, with drawings are available from  NTRAK Publishing. They have a 4 page specification sheet available from  for $2.00 from NTRAK, Inc. c/o John Cook 15913 Brawner Dr. Dumfries, VA 22026-1416

DEFINITION
Nn3 oNeTRAK modules are designed to interface with each other and with Nn3 interfaces on NTRAK modules designed for divergent Nn3 branch lines.

GOALS
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. Connected layouts encourage team building and enhance fun!
3. Easy home layout integration
4. Provide a branch line for more prototypical operations.
5. Demonstrate (and enjoy) the uniqueness of narrow gauge rail roading.

GUIDELINES
Most of these guidelines are based on existing NTRAK standards.

1. HEIGHT OF TRACK AT INTERFACE POINTS BETWEEN MODULES
Nominal 42.5 inches at interface with NTRAK modules. This is the height of the NTRAK Mountain Nn3 line. This allows Nn3 oNeTRAK modules to be connected to outside of NTRAK standard module with Nn3 on it and allow the line to cross the NTRAK red, yellow and blue main lines.  Between adjacent modules which are intended to be joined to form a continuous scene, height can vary. See "GRADES" below for limitations. 

2. FRAME SIZES
Frame lengths in multiples of one foot. Twelve inches are the minimum width. This width may be increased up to one foot, front or back for a total maximum width of three feet. Bridge modules of 24" or less in length, can be a minimum of 6" and a maximum of 12" in width. 

3. MODULE INTERFACE
Same as NTRAK with one clamp and the standard Marklin 110mm track section. Where module interfaces with modules by others, track to be 90° to end face; where module is intended to interface with owner’s other modules, any angle can be used. 

4. TRACKS 
One track is required, additional through tracks are permitted. Track to be code 40. Z/Nn3 Code 60 (nominal) flex track is permitted. Turnouts to be compatible with track selected, or include transitions which maintain rail head height. Set-back at interface ends is 55mm.

5. MINIMUM RADIUS
Minimum radius is 10" (12" min. preferred) with appropriate easements. To prevent binding the minimum length of tangent track between all reverse curves must be 3 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 or 6 inches from the nominal front so that the Fascia may be reasonably aligned. Bump outs on the modules are permitted, same as N-TRAK. Double or triple track should have 1-inch center spacing at the module interface.

7. CORNERS
Standard corners can be 24 by 24 inches, 30 by 30 inches, 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. On a 30 by 30 inch comer there is ample room for the 18-inch radius curve and easements. Minimum radius on main line for corner modules shall be 12".

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 2 by 2 feet.

10. GRADES 
Grades of 4 percent maximum across a dedicated set of modules. Grades on other modules can be created with shims under legs of modules. 

11. END TURNS 
End turns are modules that include a 180-degree curve in the track. They should be a minimum of 3 by 4 feet to allow for the 12 -inch minimum radius and easements. The distance between the ends of tracks on an end turn must be two feet minimum.

12. TURNOUT SIZES 
All turnouts should be number 4 or larger on the mains, passing sidings and interchange tracks. Number 4 minimum turnouts are also encouraged in yards for better operation.

13. ELECTRICAL
The main line has a red with green stripe female plug or panel mount socket fastened the same way as NTRAK wired as shown in the drawing, to allow reversal of modules. The white and 110 volt requirements are the same as NTRAK. There are no special DCC related wiring requirements. NTRAK standards for wire gauge suffice.

14. SCENERY
Any realistic scenery is permitted. Suggestion, only (not mandatory): Round down hills on the ends of modules so the view from an adjacent flat module looks like scenery. Colors for the fascia and skirts should blend with the scenery (generally shades of green or brown). Do not use diorama dividers.

15. SKYLINE
Skyboards or vertical scenery flats are optional.

16. PASSING SIDINGS
To enhance operations most layouts should include several passing sidings. Clubs should try to include one or more standard passing sidings in a layout. 

17. OFFSET MODULES
Offset modules provide track offsets in one-foot increments for visual variety. Observe minimum radius and tangent track between reverse curves standards.

18. OPERATIONS SCHEME
Although a stated purpose of oNeTRAK is to provide a venue for more prototypical operations, no operational scheme is specified. Clubs and individuals can tailor the operating scheme to their situation. 

19. LAYOUT DESIGN
The oNeTRAK modules have proven very flexible in layout design both as part of a NTRAK layout or when standing alone. Note that NTRAK modules with Nn3 interfaces at NTRAK-Nn3 mountain division heights can be used in a oNeTRAK Nn3 layout.