How wide should track plus ballast be on a slope to allow for scenery construction below?
Should not be less than 2", IMHO, better go for 2 1/2".
I wish I had a clear picture of what you are asking. I will assume the track bed is essentially running a contour, or just off a contour, transversely along a slope. How steep is this slope? If it is an 8% slope, you would probably want the ballast to fall at a natural angle and then have terrain continue downhill from that point. This, in turn, depends on the height of your ties and the slope of the material you have used for roadbed. There are different slopes at the edges of the roadbed material for different suppliers, and there are different thicknesses. So, each situation will call for a natural angle for the ballast sides. In turn, that angle will determine at which point you would continue your scenicking.
-Crandell
Is the track running flat, up hill, around curves? Does the mountian run up and down on both sides?
What I have done and am doing now is building my mountain rail road witdths at 4 inches. That way I can bring the screen or cardboard down to it and hot glue it to the top of the plywood or what ever meadium that you are using. From there I am making a ridge on the oppisite side of the track that wiggles like a snake does and like a ridge, or edge of a cut that runs along the side of a mountain. That gives you plenty of room to run your cork, ballast, boulders and maybe a few poles or signs along side. If you want to narrow it a bit here and there, that would look just great. I ran the line between Roseville Ca.and Reno Nv. over the Donner summit, and believe me there times that you wondered if there was road bed under you. So it is O.K. to very narrow spots as as wide spots. Maybe a few even wider that 4 inches for a siding or a spur to set out your M of W equiptment out on.
Hope that helps a little. Remember, Plan, Build and if you don’t tear it ou and try it again. Be patient and you will have a nice, fun and a beautiful rail road to run your trains on.
John L.
Full scale dimensions:
Width of sub-ballast, 22 feet. That’s the ‘shoulder’ that the ballast bed sits on.
Width of space allowed for drainage ditch, uphill side, 12 feet to point where far edge of ditch reaches the sub-ballast edge height. The bottom of the ditch is about 3/4 of the way over.
Slope of land downhill from edge of sub-ballast, “To fit local soil conditions, but not less than 1.5 feet width per foot of drop.”
Information gleaned from BNSF standards for light traffic and industrial track.
Given that light traffic track calls for a sub-ballast width of over 3 full-scale inches in HO, I wonder what the standard is for heavy duty track like that of the transcon route…
Chuck (Modeling Central Japan in September, 1964 - with sidehill cuts blasted out of solid rock)
It will vary somewhat depending on the lay-of-the-land. Notice that the slope is 1-to-2 and more, not the 1-to-1 (45 degrees) typically seen on model railroads.
Mark
There is a term used to define the angle that a particular material (in this case ballast) will start to fall of it’s own weight and granular size; The Angle of Repose. Most granular materials have an angle of between 40 and 45 degrees. I generally try to keep a 45 degree angle but as with most model layouts, space is at a premium and we wind up with very steep landscapes between two elevations of track. I have many on my layout that are solid rock walls because any other terrain material would look rediculous. Hope this is what you were looking for.
bob
I was referring to roadbed shoulders and fills, not stone cliffs, etc.
As to be expected, stone cliffs are steeper than talus and scree slopes.
If you’re buliding a mountain railroad, John has some very good advice. Like John, my MR runs through the California Sierra Nevada, and to get over these particular mountains, you have two choices–either build up the bottom of a canyon or build high along a ridge. My Yuba River Sub is a ridge-built railroad, and I’ve used a 4" minimum width for scenery, roadbed and drop-off. It works really well for me,with plenty of clerance on the cliffsides for large locos and long rolling stock, and a ‘natural’ dropoff for ballast and scenery, even on the portions that are sheer (and I’ve got one DOOZY of a sheer drop-off, almost 6 actual feet to the garage floor).
4" is
Most prototypes will let the ballast fall where gravity puts it on a hillside. Here is a picture of the Lyman Viaduct on the New Haven’s Air Line between Middletown and Willimantic CT (actually between the towns of East Hampton and Colchester). Here is the viaduct as originally constructed:
In 1912, the NH decided that the structure was not suited for the weight of heavier locomotives and rolling stock. After building a culvert over the creek in the bottom, they progressively dumped tons of sand and ballast through the viaduct to create a fill. It’s no longer in use, except as a bike trail. Notice that the sides are at a 40 to 45 degree angle:
Hope that provides some fuel for the imagination.
You are being deceived. The top “edge” on the slope is further away from view than the low edge, making it appear the slope is steeper than it actually is.
Mark
Here are some vital statistics from prototype AERA specifications, circa 1938, presumably for main tracks.
Subroadbed grade width of 19’
Ballast width of 16’
1" drop for each 3" distance for ballast from tie edge to 18" from subgrade edge.
Drainage ditch at least 6" lower than subroadbed.
An acceptable compromise for track ballast slope for modeling is 1 unit of drop for each 2 units of horizontal distance (1 to 2 versus 1 to 3 prototype ratio). A 1-to-1 track ballast slope takes modeling license to the toylike.
Mark
Maybe, if I were going just by the picture. But I’ve stood there. It looks steeper in person. Steep enough that you stay away from the edge.
I am afraid of standing near vertical edges dropping to oblivion. Fear exaggerates!
Based on my decades of observation, loose rock material is somewhat stable at a ratio of something like 1 to 1.5, that is, 1 unit vertical to 1.5 unit horizontal. Nature, I think, is happier with 1 to 2 in the longer term, but she will eventually want rock debris to end at 1 to 1 near horizontal over the millenia.
Mark