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Friday, April 6, 2012

Part 4. Roadbed Construction

Just like the real railroads, if the track isn't up to par, then your trains won't be either.  The roadbed on a real railroad is the fill dirt, trestles, bridges, track, ballast, and anything associated with the track.  On a model railroad, the track sits not on gravel, but a pathway made smooth either through materials like cork roadbed.  The model track also needs a strong supporting structure, which is usually connected to the bench work in some way.  Using the bench work as a supporting structure gives the track a really stable quality.  But what kind of roadbed goes with the type of construction technique used?

Here is what I have found out, after consulting my old Model Railroader Magazine, Classic Toy Trains, and the Internet about roadbed:

Foam Board Method:

The foam board type of construction uses foam board insulation for the scenery base.  Underneath the foam, there is often times a lattice work of bench work.  The track can be put straight onto the foam, however, more often than not, cork road bed is between the track and foam.  Building foundations (yes are apart of the road bed) support the buildings and keep them level.  This is demonstrated in the diagram below:

Foam and Plaster Cloth Method:

This idea of constructing a railroad was the brainchild of the good people at Woodland Scenic's.  The idea was to substitute lumber for foam for the majority of construction.  The foam would be used as a support for the roadbed, fascia, and scenery.  Then plaster cloth, which is a membrane embedded with plaster, is used to sculpt the scenery. Woodland Scenic's sells everything that is needed, and it is explored in depth on a series of videos by Woodland Scenic's here.  It is an overview on building a layout, Woodland Scenic's style.

Here is the diagram showing the roadbed and bench work:

  • Pink:  backboards or supporting foam boards
  • Light Blue: risers or support for track
  • Peach: lumber or wood base
  • Blue: backdrop
  • White: plaster cloth
  • Scribbles: newspaper wads or similar objects
Paper Shell Scenery  

Paper shell scenery, as a layout construction method, is relatively new.  Therefore, it is going through a trial and error phase.  However, the results in a recent Model Railroader Planning issue, look promising.  The idea behind paper shell scenery is to use heavy paper to create a landscape that is flexible, molds to any landscaping challenge, and creates a pleasing landscape, but I'm getting ahead of myself.  Basically, paper shell scenery can be used like the foam and plaster cloth method above.  The track is supported in the same way, or alternately, by wood as described in the "cookie cutter" construction method below.

Cookie Cutter

Roadbed in the cookie cutter method of layout construction is made using a supporting framework of lumber to form a pathway for track to travel upon. The supporting framework is attached to the bench work, allowing for the track to be anchored solidly.  Furthermore, the lattice, made up of cardboard strips, can easily be attached and weaved into a matrix of supporting cardboard.  The cardboard supports the plaster cloth, which supports the scenery.  This allows for a very light weight layout, that has a very flexible scenery base.  The idea is outlined below:

The lowest portion of peach and white colored shapes represents the bench work.  The gray strip on the top portion is the roadbed for the track.  Structures would also be supported along the track via the raised portion.  Cookie cutter gets its name from cutting out portions of the table top (not shown) to allow the track to move along the surface.  This all-wood design is strong, and can be made very light.

Table Top

Finally, there is the classic table top.  Most people know about this style of construction, and hence, know all about the roadbed used.  I'll cut some time here, and just say that the track is put on top of cork roadbed strips.  Other than that, the track can be supported just about any way described above. 

And here is an overview on roadbed.  I bet you didn't think I could dedicate a section to a seemingly simple step huh?  The next step is explaining power in part five!

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