# Small Hill and Undulations



## Matison (12 mo ago)

Hello. I’m on the third revision of my very first layout. I am currently building N SCALE, but my question is somewhat generic to size. 

The first two layouts that I built were not very feasible, nor were they particularly realistic. The layout that I just stripped could have been named “Trestle World”. I have a relatively small L-shaped layout. In order to reach an upper rocky pass, I needed to get the tracks up to 6”. The problem was that the lead-up incline took almost half of the track, while at 5 degrees incline or more, while the downhill part did basically the same in reverse, and at a steeper angle to boot. (I know about the 2-3% maximum slope) So, that one did not work out. Such a waste of glue and balsa…
I stripped everything off the foam and introduced many small rolling hills and undulations, just like in the areas where I had grown up. 
I have a new problem. I don’t want bridges at every little rolling hill, but these small hills are too large for me to be able to lay the track flat across them. What do I do to keep my track somewhat straight on the many rolling hills without building another large group of bridges? I want it to look natural, and have no idea what to do. I am still a beginner, but I’m learning as I progress.


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## MichaelE (Mar 7, 2018)

The hill would have either been carved out for the track, the track would have been laid around the hill, or a tunnel would have been drilled to go through it.

The Swiss know all about building a railroad in the hills. Really big hills.


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## OilValleyRy (Oct 3, 2021)

Prototype railroads have the same problem, and developed a solution most of us model. It’s called “cut & fill.” They will cut (or blast) out a portion of a hill where track will be laid, and repurpose that material where low areas needs to be filled in order to maintain a consistent grade. Hence, Cut… and Fill.
You’ve probably seen this yourself. The end result is a blasted rock “wall” along side the tracks. The same method is used in roadway construction. A common sight in mountainous terrain like the Appalachian and Rocky Mountain ranges.


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## CTValleyRR (Jul 26, 2014)

Matison said:


> Hello. I’m on the third revision of my very first layout. I am currently building N SCALE, but my question is somewhat generic to size.
> 
> The first two layouts that I built were not very feasible, nor were they particularly realistic. The layout that I just stripped could have been named “Trestle World”. I have a relatively small L-shaped layout. In order to reach an upper rocky pass, I needed to get the tracks up to 6”. The problem was that the lead-up incline took almost half of the track, while at 5 degrees incline or more, while the downhill part did basically the same in reverse, and at a steeper angle to boot. (I know about the 2-3% maximum slope) So, that one did not work out. Such a waste of glue and balsa…
> I stripped everything off the foam and introduced many small rolling hills and undulations, just like in the areas where I had grown up.
> I have a new problem. I don’t want bridges at every little rolling hill, but these small hills are too large for me to be able to lay the track flat across them. What do I do to keep my track somewhat straight on the many rolling hills without building another large group of bridges? I want it to look natural, and have no idea what to do. I am still a beginner, but I’m learning as I progress.


So you just learned the hard way that lots of vertical separation requires a LOT of space, and isn't feasible on many layouts. I did that too, on my first foray into the hobby back in the '70s. Real railroads use cuts and fills to manage undulations in terrain, and they try to use material that they remove from a cut in nearby fills. Or, if the hill is a little bigger, they go around it. As a last resort, they use a bridge or a tunnel. 

While I admire your courage, and hate to send you back to the drawing board, I'm going to recommend you do just that. Lay your track FIRST, then create believable terrain around it. That way it will LOOK like the hill was there first, and the railroad cut through it, or filled the valley beneath it. It also allows you to lay dead level track, at a gentle incline if desired, which will greatly improve the operations of your trains.


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## traction fan (Oct 5, 2014)

Matison said:


> Hello. I’m on the third revision of my very first layout. I am currently building N SCALE, but my question is somewhat generic to size.
> 
> The first two layouts that I built were not very feasible, nor were they particularly realistic. The layout that I just stripped could have been named “Trestle World”. I have a relatively small L-shaped layout. In order to reach an upper rocky pass, I needed to get the tracks up to 6”. The problem was that the lead-up incline took almost half of the track, while at 5 degrees incline or more, while the downhill part did basically the same in reverse, and at a steeper angle to boot. (I know about the 2-3% maximum slope) So, that one did not work out. Such a waste of glue and balsa…
> I stripped everything off the foam and introduced many small rolling hills and undulations, just like in the areas where I had grown up.
> I have a new problem. I don’t want bridges at every little rolling hill, but these small hills are too large for me to be able to lay the track flat across them. What do I do to keep my track somewhat straight on the many rolling hills without building another large group of bridges? I want it to look natural, and have no idea what to do. I am still a beginner, but I’m learning as I progress.


Matison;

The others have told you about the common technique of "cut & fill."
Another alternative to bridges, commonly used on small undulations, is culverts. These range in size from a fairly small, (12") pipe, up to concrete, or wood, structures that resemble miniature versions of bridges, or tunnel portals.
Culverts are very common on prototype railroads and highways. They are not as common on model railroads.
I have several on my own N-scale layout. They are a nice detail, and easy to make. I made some "corrugated pipe" culverts by wrapping very thin brass sheet around a machine screw and pressing the brass foil into the threads of the screw by rolling it across some cardboard. You could do this with aluminum foil, but the culvert would be quite fragile.
I also have wood cribbing and "concrete arch" culverts. The first type I made of basswood (which is stronger than balsa, and I highly recommend it. The concrete arch is simply a piece of Masonite, with a hole drilled through it and the bottom part of the hole cut off. A bit of concrete color paint finished it off. The first two photos show some bridges I've scratchbuilt from basswood. The third photo shows the little yard at Cedar Falls, WA. There are drainage ditches on either side of the tracks, and the ditches are joined by wooden culverts.
Culverts & bridges are essential for drainage. Without them track & roads would wash out when it rains heavily.

Good Luck & Have Fun;

Traction Fan 🙂


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## JeffHurl (Apr 22, 2021)

I would lay the track on flat panels foam, then layer up the hills and/or carve out the valleys where the track isn't.

If you want some inclines, try woodland scenic incline starters, and go up 1/2" every 2 feet. That ends up being 2%.


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## Severn (May 13, 2016)

If it's not too much pre existing you could do the "skeletal" approach... Which I've only seen in vids but is appealing to me as I did the build it up and cut it out approach... which is certainly viable but I've found nice consistent grading to be hard ... I mean I didn't get into this to be a road engineer.

So in this other approach...

You lay out the track run using for example thin pieces of wood and these are graded and curved as you wish... By holding it to height by some kind of pole, dowel or pylon structure which rests on your underlying structure/top/bench.

You get all that in place, get the track on it and even wire it up and test it...

Then you build your land form around it, enclose or span the gaps as you desire. 

This may in fact be quite flimsy material overall... Such as screen, paper, cardboard as the base layer... But you build it up and finish it in that way -- and at least by the vids it seems to have some benefits in that whole thing is kind of a shell which is where your energy goes more efficiently.

See marklin of Sweden for example vids but there are others.


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## OilValleyRy (Oct 3, 2021)

The method Severn mentions above is in fact the method I’ll be using.
Plywood (or other wood) sub roadbed on risers, positioned 2” above my cross member supports.
2” foam, where used, will align level with the sub roadbed. A wire or cardboard net & plaster shell is simply stapled to the edge of wood sub roadbed. Basically wood where track will be. Foam sheet where roads, structures, and water will be, plaster shell everywhere else.

Some added benefits of this method are that the sub roadbed is secured to risers from below, which means you can remove the track from the layout with just a few screws & disconnecting feeders. So if a layout needed to be dismantled, the finished track (ballasted etc) can be completely reused 100%. 
Additionally, it enables you to detach sections of track after operational testing, and moved to the workbench for ballasting, detailing, painting, etc. So i.e. if you wanted to model the actual signal detection wiring that spans rail joints, or hot pots, etc it’s much easier.


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## CTValleyRR (Jul 26, 2014)

You can also use extruded styrene insulating foam panels for your layout surface. This gives you some ability to carve down into the terrain as well.


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## Severn (May 13, 2016)

I think if your track runs are flat .. then just put them on something like foam or cork, or whatever.

The problem comes into play when you want a grade from point a to b. It's compounded when that path curves.

If you have to cut away to get it, you're confronted with a road building problem... Which seems hard ... Sure chopping away foam is easy but doing it to produce a consistent 2% graded path with a curve is either hard or seems hard to me.

This is where the "skeleton approach" seems to have merit because the track path sits on some kind of risers that are precut to grade.

Put them down, add a track path base (such as very thin slats of "hobby wood")... And you've got it.

That to me is it's big appeal. The downside is it appears you do have to know what you want ahead of time. For people like me this is a big problem. I don't have any idea what I'm doing!

So this is where the foam chop seems appealing from the experimental standpoint. Glue up some layers, look at it. Decide on some route, chop chop chop.

Since I've only done the foam chop I can say it's certainly flexible. But it's very hard to get a nice smooth grade through that path and at least in my case I've had to go back and make a lot of tiny adjustments to the track grade by running my engines through it. (Edit )

And adjusting low and high points...which is a pain in the buffer.


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## CTValleyRR (Jul 26, 2014)

We're generally not recommending carving into the foam scenery to make track grades. Most of us would recommend using the lowest track location as "elevation zero" and use WS incline starters (or a home-made equivalent that you make with a high degree of accuracy on shop equipment) to form a nice, smooth grade. For each 1" of elevation gained, you can add a layer of extruded foam to make a new flat surface on which to either lay your track or your next course of incline starters.

Carving down into the foam is for creating scenery / landforms, which require much less precision (arguably, precision is a detriment when doing so as it makes things look too artificial).


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## Severn (May 13, 2016)

That's then similar to riser/skeletal approach assuming you use ws risers to layout the track path first. I actually bought a bunch of that stuff and used it to create a loopy thing. I realized I could have used my pink foam to create similar risers but I felt lazy about the whole thing and went for the expensive preformed solution. I don't think I'll do it again which is BS but if I used the pink foam I'd have to build a good foam cutter for the job to get reasonably precise undulation free cuts going. Which unfortunately even with the ws risers I probably created a few myself just because I didn't take the time or really, realize the importance of a smooth track path.
If I did it all again I'd be very very tempted to top the path before Cork with thin slats of wood and then go from there.
(Note I also chopped down or through foam built up because I had no plan and just decided "that's where I want to go". So if you pre know where you want to go this is the best but I don't so what are you doing to do but make it work...?)
It might be worth noting I bought a chainsaw and have enclosed it in a glass case within reach of the layout. There's a hammer on a chain too. And just to cover all possiblilities, I painted in big large letters "In Case of Emergency Break Glass" on it. Metaphorically speaking really. In my mind it's an option.


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## MichaelE (Mar 7, 2018)




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## traction fan (Oct 5, 2014)

Severn said:


> That's then similar to riser/skeletal approach assuming you use ws risers to layout the track path first. I actually bought a bunch of that stuff and used it to create a loopy thing. I realized I could have used my pink foam to create similar risers but I felt lazy about the whole thing and went for the expensive preformed solution. I don't think I'll do it again which is BS but if I used the pink foam I'd have to build a good foam cutter for the job to get reasonably precise undulation free cuts going. Which unfortunately even with the ws risers I probably created a few myself just because I didn't take the time or really, realize the importance of a smooth track path.
> If I did it all again I'd be very very tempted to top the path before Cork with thin slats of wood and then go from there.
> (Note I also chopped down or through foam built up because I had no plan and just decided "that's where I want to go". So if you pre know where you want to go this is the best but I don't so what are you doing to do but make it work...?)
> It might be worth noting I bought a chainsaw and have enclosed it in a glass case within reach of the layout. There's a hammer on a chain too. And just to cover all possiblilities, I painted in big large letters "In Case of Emergency Break Glass" on it. Metaphorically speaking really. In my mind it's an option.


Severn;

Yes, I guess we've all had thoughts of "smash it & trash it at one time or another. LOL 😄 On roadbed, it has to be smooth, flat, and rigid. "Flat" in my context here dosen't mean no grades allowed, but rather that you can lay a long level or metal yardstick straightedge along the roadbed, and not see any dips or bumps under the straightedge. The smaller your modeling scale, the more severe the dips & bumps look, but its quite a problem in any scale. I model in N-scale, so "small hills & undulations" in the actual roadbed itself, make the trains move like ships in heavy seas! I make my sub-roadbed fron 1/4" Luan plywood with 3/4" x 1/4" supporting stringers glued under each edge. This forms a sort of "inverted double L-girder", or "continuous deck-girder bridge" structure which is extremely strong and dead rigid, despite its light weight. (see photos) 
For roadbed, I cut my own from 1/8" Luan on a bandsaw & sand the edges to a taper. In my opinion, this gives the track a firm, even, base, better than commercial foam or cork roadbed.

Traction Fan 🙂


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