N Scale Module Construction Journal

Denway Overpass (free-mo N, mini-mo)

Wesley Steiner

Last Updated: 22 Apr 2005

This document attempts to capture the design, construction and development of my Denway Overpass free-mo N scale module. Denway is a fictitious area located along the CN main lines in eastern Canada (the name is a contraction of the title of an article that appeared in the Oct. 2001 issue of Model Railroader called "Wooden Highway Overpass").


A mini-mo is a free-mo module designed to extend the distance between the main free-mo modules (yards, towns or industries) as quickly and cheaply as possible. They are usually only 12 in. wide, incorporate a slight turn, have a single main line w/o turnouts and do not have permanently attached legs. These features make them inexpensive and quick to build. I like to add at least one main scenic feature to my mini-mos so in this case it will be an old wooden bridge overpass based on the prototype in the article.


Here the basic module frame has been completed and the foam sub-roadbed surface has been rough cut to shape. The module has an approximate 32 degree turn. As you can see most of the module is built up from foam and the two wooden end-plates. This construction technique results in an extremely light weight module for ease of transportation and handling during set-ups.


The underside of the basic module showing the details of the endplate construction. Longitudinal support will be provided by the 1/8 in. fascia material that will be glued to the wood endplate areas and to the foam.


Strips of foam were glued to the surface along the center line (to form the mounds for the overpass) and rough shaping of the module sides and the landforms has been completed.


Cork roadbed has been glued in place. This will help while shaping the final form of the landscape especially in the ditch area along the track.


Here is the completed module frame with both side fascia panels in place. The fascia sides add to the structure of the module by providing longitudinal support for the foam. The fascia panel is glued to the foam using Liquid Nails for Foamboard and to the wood endplates with carpenters yellow glue. The foam landscape has been shaped to its final form using a foam rasp and sandpaper.


The entire module, including the end plates and foam surface area, has been coated with a paint sealer in an earth tone color. Also the main track, ME Code 55, has been glued in place and feeder wires have been soldered to the rails.


Here the track has been painted and weathered and the foam scenery has been painted. I first spray the top of the track with a grimy black then shoot from the sides with a rust color to get the rails. Next I use weathering powders to add rust and discoloration to the ties and finish the whole thing off with a coat of flat clear finish so the weathering won't wash off during ballasting. The foam was spray painted using a mixture of Woodland Scenics earth tone paints.


This photo shows the mini-mo connected to my 4' Frend Track module. Since there is no module to connect to at the other end the mini-mo is supported by a piece of ½" conduit. This single leg can be attached at either end of the mini-mo to assist when setting up the modules and when there is no other module to connect to.


I use standard broom handle clips to attach the conduit leg to the frame. These clips have enough tension to hold the leg in place but are loose enough to twist for height adjustments. Since the module weighs in at only 8 lbs the tension is enough to hold up one end of the module.


In preparation for our first public showing at the 2004 Western Prototype Modellers meet in La Habra, CA, I wanted to lay down at least minimal ground cover scenery.


... stay tuned here for progress updates ...


© 2017 by Wesley Steiner - mail@wesleysteiner.net
home page - previous page