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Scenery: How to model Grade Separated Rail Lines

December 17, 2008

We’ve probably at one time or another, encountered a grade-separated highway and railroad line. There are many famous locations all around the world that feature the railroad and a road passing on different levels. This feature can really add intrest to a model scene, and it’s something that probably could be part of just about any layout depicting an era after 1920 in the United States. Great Britian is known for it’s huge labyrinth of “viaducts” around London, often seen in films and television shows. These distinctive brick arched viaducts still are used by british railroads today.

Grade separation was principally designed to keep automobile traffic from interfering with busy mainline railroad operations by separating the grades (levels) of both the highway. Typically there are two types of grade separated bridges:

One type is when the railroad is built on an embankment or a fill, and the road passes through the fill, usually keeping the road mostly level.

The second type keeps the railroad mainline on ground level and the road is built underneath by excavating the earth beneath the rails and creating a small “V” shaped depression, enough to fit the largest trucks under the bridge.

There are variations of both versions allowing shallow embankments and shallow  depressions to keep costs down. This can vary in height from 20 or more feet off street level to a downright dangerous 9 feet of road clearance in some older grade separated projects and rural areas. A typical clearance is about 14 feet off the road surface.

Art Deco
(Walther’s Photo)

(Walther’s Photo)

Bridges come in a wide variety of types, but spans that are plate-girder in construction, typically with concrete embankments, are most commonly found in North America. In older portions of the railroad, arch bridges of stone and brick are more common. Short timber trestles are also found in the west and southern united states where there is an abundance of trees.

Perhaps this is a scenic feature that should be incorporated into your layout in one form or another. They’re attractive ways to break up the usual mainline look.

One Comment leave one →
  1. December 24, 2008 7:49 pm

    I agree, grade separation adds so much more visual appeal and depth than a typical grade crossing. I have a few planned for my layout. I like what I have looked at so far on your blog and look forward to your progress.


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