Roadbed Height

[Christopher62]

In looking at railroad layout and prototype photos I notice that in some instances the track is raised up on a berm, but in other areas the track is flat on the ground. Can anyone tell me what dictates when/where/if the track needs to be raised or not?

Also, how is this reflected on the layout? Do you slowly decrease the angle of the cork roadbed to ground level, or do you raise the surrounding ground and slowly eliminate the cork?

Thanks all!

 

[Jim Krause]

The prototypes use the raised roadbed to assure good drainage under the track and the ballast holds the track in place. What we see on models is the shape of the ballast which is just cosmetic since the rail is either glued or nailed down. There is also a sub-roadbed under the ballast which is the major supprt for prototype tack. Sidings and branchlines usually use less elevation or in the case of some logging railroads, none at all. Sidings sometimes get filled in over the years with dirt, grass, junk etc, until the ties are completely covered. You an taper the roadbed to simulate going from main to siding and eliminate the roadbed entirely if you want. You can also fill in around the cork or foam roadbed to simulate less roadbed height.

 

[kitsune]

Bottom line: money.

It costs a lot of money to lay nice track with good, high ballast profiles. So even on a fairly well-to-do class one, you'll see sidings and spurs given increasingly less profiling, less ballast, etc.... You might find the main well above the average land surface on a large fill of subroadbed, with neatly ballasted ties, and then find the siding just a bit below that in height, and then find a spur to some old industry that is barely in more than mud.

Some railroads, being poor at construction, didn't even go so far as that with their mainlines. Interurbans, for example, tended to have low ballast profiles, as did narrow gauge lines. And don't forget that ballasting and subroadbed settles over time: Milwaukee had the finest ballasting and profiling on its Pacific Extension when it was built in the teens, but by the 1970s, it was barely sitting in a thin dressing of cheap gravel ballast.

As for modeling it, try differeing thicknesses of roadbed. Many people modeling thin roadbeds do what Bill Darnaby did and use unsplit n-scale cork roadbed under HO track.

 

[Christopher62]

Thanks guys! Great input. Actually, the more questions I ask the more I realize how little I know! Oh well, I guess that's all part of the hobby and how you learn things...

 

[MasonJar]

Even if the roadbed is not raised above the surrounding terrain, there are (more often than not) ditches cut on either side of the track. This is one reason to use foam as the deck of your layout - you can cut into it for such features.

I remember reading in MR a while back about making a hot wire cutter with the proper profile so the drainage ditch and roadbed contour could be easily cut into foam.

Andrew