Concord Model Railroad Club

HO Scale Standard Gauge Modular Standards

Adopted on September 8, 2003
Last edited on October 29, 2006

Module Construction

General

Modules shall be constructed with light weight materials, with a foam core, furnature grade plywood ends, and luan facia and backdrops. Modules ended up being built with 3/8" plywood, instead of luan. Using luan, and building up T and I beams added complexity to the construction process, without removing significant weight.

Straight Modules

Straight modules shall be no longer than 6 feet, and no wider than 3 feet.

Corner Modules

Corner modules shall fit within a 6 foot by 6 foot square. We've been building corners using two 2x6 modules.

Backdrop

The backdrop shall be 18 inches high. To date, we have not built backdrops on any of the new modules. Backdrops will be built later, and designed to be attached after the layout is assembled. Since the new modules are designed so they can be flipped around, we don't want a permanment backdrop obscuring the view during a show.

Supports

The top of roadbed shall be 40 inches, with adjustable supports that allow the modules to be lowered to 38.5 or raised to 41.5 inches.

Mainline Track

General

All track measurements are made from the front, or viewing side of the module, to the centerline of the track. All mainline track shall be code 100 nickel silver. Mainline tracks shall be set back three inches from the end of the modules. The first 6 inches of track shall be straight, creating a twelve inch straight transition between posible reverse curves. Rail joints, except at turnouts, shall be soldered.

Turnouts

Mainline turnouts shall be no smaller than #8. Smaller sized turnouts may be installed to serve industry sidings, provided that mainline trains do not travel through the diverging route.

Turnouts shall be powered with slow-motion, stall type switch motors.

Spacing

A single mainline track shall interface between modules, and be laid 7 inches from the front of the module. Modules that are expected to interface with standard NMRA modules shall have a second track, laid 5 inches from the front of the module. Multiple modules that connect together to make a scene, need only comply at the ends that connect to other modules.

Wiring

General

The track power bus shall be constructed with 12gauge wire, terminal strips, and spade connectors. Short 24gauge wire shall be used for track feeders. Two-pin connectors shall be used for each mainline between modules. Heat-shrink tubing shall be used to cover solder joints.

Gaps

Gaps, or insulated rail joiners, shall be installed across both rails within the module; solid rail jointers shall be used between modules. A "gap-switch" shall be installed, which when in the closed position shall allow power to flow through the module. This may sound like a good idea, but in practice it adds complexity to the design, and could result in failures if the switch was changed during layout operations. We'll continue to use insolated railjoinings at the end of the module, and unplug the track bus.

Protection

Circuit protection shall be installed in such a manner to prevent a single short from shutting down the entire layout.

Special Purpose Modules

Corners

Two 6 x 6 foot corners to be used at joint CVMRRC/CMRC meets

Four 4 x 4 foot corners to be used at small shows, similar to the NH History Museum, and Pemi Valley Shows.

NMRA Compliant

Twenty linear feet of NMRA compliant modules to be used for interfacing with the Bedford Boomers, or similar group. Both track and wiring!

Transition

Two six foot modules that contain two feet of single track, and four feet of double-track, meeting the NMRA spec at the interface. When placed so that the two NMRA ends join, the modules will form an eight-foot passing siding. Optionally, we could build the NMRA ends with all four tracks, forming a four track "yard" when connected. We have decided to use the four-track yard configuration, and model that to be the northern terminus of our Concord to White River Junction sectional layout. The yard will roughly be the Westboro frieght yards.

Concord Model Railroad Club
Home > Standards
History The Club's first modules were built following an NMRA-like standard. This is the same standard used by the CVMRRC club. Many members became displeased with the parallel, racetrack-like mainline, and started to consider other options, like the emerging FreeMo standards. It was thought that the NMRA standard was holding the Club back from designing and building a layout focused on operations. The standards to left were written with the goals of combining the NMRA specs with the FreeMo standards, along with the numerous lessons that Club members have learned. The results are lighter modules, less track joints, more design flexibility, yet retaining the ability to connect to a "legacy" module.	HO Scale Standard Gauge Modular Standards Adopted on September 8, 2003 Last edited on October 29, 2006 Module Construction General Modules shall be constructed with light weight materials, with a foam core, furnature grade plywood ends, and luan facia and backdrops. Modules ended up being built with 3/8" plywood, instead of luan. Using luan, and building up T and I beams added complexity to the construction process, without removing significant weight. Straight Modules Straight modules shall be no longer than 6 feet, and no wider than 3 feet. Corner Modules Corner modules shall fit within a 6 foot by 6 foot square. We've been building corners using two 2x6 modules. Backdrop The backdrop shall be 18 inches high. To date, we have not built backdrops on any of the new modules. Backdrops will be built later, and designed to be attached after the layout is assembled. Since the new modules are designed so they can be flipped around, we don't want a permanment backdrop obscuring the view during a show. Supports The top of roadbed shall be 40 inches, with adjustable supports that allow the modules to be lowered to 38.5 or raised to 41.5 inches. Mainline Track General All track measurements are made from the front, or viewing side of the module, to the centerline of the track. All mainline track shall be code 100 nickel silver. Mainline tracks shall be set back three inches from the end of the modules. The first 6 inches of track shall be straight, creating a twelve inch straight transition between posible reverse curves. Rail joints, except at turnouts, shall be soldered. Turnouts Mainline turnouts shall be no smaller than #8. Smaller sized turnouts may be installed to serve industry sidings, provided that mainline trains do not travel through the diverging route. Turnouts shall be powered with slow-motion, stall type switch motors. Spacing A single mainline track shall interface between modules, and be laid 7 inches from the front of the module. Modules that are expected to interface with standard NMRA modules shall have a second track, laid 5 inches from the front of the module. Multiple modules that connect together to make a scene, need only comply at the ends that connect to other modules. Wiring General The track power bus shall be constructed with 12gauge wire, terminal strips, and spade connectors. Short 24gauge wire shall be used for track feeders. Two-pin connectors shall be used for each mainline between modules. Heat-shrink tubing shall be used to cover solder joints. Gaps Gaps, or insulated rail joiners, shall be installed across both rails within the module; solid rail jointers shall be used between modules. A "gap-switch" shall be installed, which when in the closed position shall allow power to flow through the module. This may sound like a good idea, but in practice it adds complexity to the design, and could result in failures if the switch was changed during layout operations. We'll continue to use insolated railjoinings at the end of the module, and unplug the track bus. Protection Circuit protection shall be installed in such a manner to prevent a single short from shutting down the entire layout. Special Purpose Modules Corners Two 6 x 6 foot corners to be used at joint CVMRRC/CMRC meets Four 4 x 4 foot corners to be used at small shows, similar to the NH History Museum, and Pemi Valley Shows. NMRA Compliant Twenty linear feet of NMRA compliant modules to be used for interfacing with the Bedford Boomers, or similar group. Both track and wiring! Transition Two six foot modules that contain two feet of single track, and four feet of double-track, meeting the NMRA spec at the interface. When placed so that the two NMRA ends join, the modules will form an eight-foot passing siding. Optionally, we could build the NMRA ends with all four tracks, forming a four track "yard" when connected. We have decided to use the four-track yard configuration, and model that to be the northern terminus of our Concord to White River Junction sectional layout. The yard will roughly be the Westboro frieght yards.