What are climbing spirals, what do they do and how do you make a Helix?


Climbing spirals, or sometimes called “helix,” are a perfect way to gain height on the model railroad. We eagerly use it when designing and building a model railroad. Climbing spirals have many advantages for a model railroad:

  • Rise in a small area, thus saving space
  • Additional siding for model trains, sort of a shadow station on the way!
  • Can be built in many shapes and sizes

What do you need to consider? In this article, we will tell you more about the phenomenon of climbing spirals.

The turret in H0, over 1 meter high in Roco radius R3 and R4

When to use a Climbing Spiral?

Climbing spirals, as mentioned above, are very useful for bridging heights quickly and compactly. Thus, you can apply climbing spirals to reach various levels in the landscape, and thus also create more unpredictability of the course of the model trains.

However, we use the climbing spiral most often to build a shadow station under the layout. Why do you ask? Because you can park most of the trains there.

And the moment is often quickly reached when we have more trains than tracks to park them.

Climbing spirals, tips for a higher level!
Multiple shadow stations provide many sidings for your model trains
Climbing spirals, tips for a higher level!
Spirals are also useful for putting on multiple levels of scenery.

Shadow stations

As mentioned, we often have more trains faster than tracks to run them. Then shadow stations are the ideal solution to this problem. But where do you place them?

Most choose to place a shadow station at the back of a layout, but then you’re often stuck with accessibility. Murphy’s Law dictates that things always go wrong where we don’t want them to.

A more efficient solution is under the model layout, where we often have the space and overview. A climbing spiral is then the perfect solution to get there!

Slope percentage

There is also a downside to ascending and climbing model trains. If the gradient is too steep, the locomotive will skid and not move forward. Descending is again not a problem with this, but when the cars decouple they start rolling faster and faster.

You also have to deal with additional wear and tear, for example, the engine will have to deliver more and thus will need maintenance sooner. And what about the non-slip straps, you may replace them a little more often. But is this all really so bad? No, we don’t think so. The advantage of a climbing spiral far outweighs the disadvantage. And some locomotives are more sensitive to this than the others, and if so, you can easily replace the parts as they wear out.

However, we do use a guideline in terms of slope angle:

Length of trainsScale H0Scale N
Short trains <4 cars4%3%
Average trains 3 to 6 wagons3 %2,5 %
Long trains > 6 cars2,5 %2%

Now this is just a guideline. Because this is determined by a number of factors such as weight, locomotive strength, traction and rolling resistance.

Want to be sure? Place an oval on a board with at least 1 meter of track length and run a train in circles. Then elevator the board up an inch on 1 side and see what happens. Representatively, every centimeter of elevation on 1 meter of track is equal to 1% slope. So you can quickly find out what your trains can handle.

Helix shapes, intermediate sizes and radius

Climbing spirals can be built in many forms. The most well-known is round, but consider also oval, square (with round corners, of course) or triangle. The longer a rotation becomes, the lower the gradient will be. So an oval causes you to have less slope angle than a circle when the same radius is used.

If you want to give the circle an equal angle of inclination as the oval, you will have to make the circle larger in radius. And there is profit there too! The greater the radius, the less the rolling resistance when cornering. And there’s a side benefit there from a lower slope angle.

In addition to the shape and radius, you can also look at the intermediate size of the layers. The space between each layer also determines the slope angle. But don’t be too economical with that! It is tempting to take the minimum spacing so that your locomotives can just pass under it. Then again, Murphy, you have to be able to deal with a derailment or calamity.

This is what we are using as a gauge:

Scale H0Scale N
Minimum spacing80 mm50 mm
Maximum spacing100 mm60 mm

Keep in mind that the thickness of 1 layer of wood, the height of the rails and any cork will come off this. So the measure is not from top of layer to bottom of next layer, no from the top of both wood layers.


Why are climbing spirals often so high?

We often get the question, why are climbing spirals so high. A great example is the climbing spiral with which we open this article. This one has a height of 100 cm! And why not actually? You want to maximize the space you have.

Make sure you have enough space. 20 cm as here is really not much for your hand and arm.

Besides this, it also has a very useful function. I wrote earlier about Murphy’s Law, where you don’t want it, it always goes wrong. And then you have to reach it with your hand, arm or upper body.

If you don’t maintain enough spacing, it’s hard to reach it without bumping into it or knocking over entire trains. And believe me, nothing is more frustrating than playing dominoes in a full shadow station because 1 wagon derailed somewhere.

But we have a clever tool for this, too:


For every 10 cm of depth from the reachable point, provide 10 cm of height
I just wrote about that 100 cm high climbing spiral. The shadow station is 100 cm deep, so then that means I want 100 cm of height to get to the back of the shadow station with my body.

Should I have this depth and be able to reach it not only from the front but also from the back, I could halve that because the reachable depth would then be 50 cm from each jug. And in the project of the “tower” this is applicable, because from the other side there will be a second shadow station which I will put at 50 cm height. It is accessible from two sides.

Get smart with a climbing spiral

Making good use of the height, of course, means more layers and rings. And that’s just fine! Let the trains here run congestion in both directions! Thus, there is always a train ready to get out and you don’t have to wait either. And that way you also have an extension of your shadow station right away! The “tower” can hold 10 trains stationary in both directions.

Utilize the available space, as much as possible. And why not, the empty space under a shadow station is only useful for boxes…. But we are building a model railroad and not a closet.


Always feed a climbing spiral every two rings maximum, no more! Preferably still in each ring. Why? One revolution creates a considerable length of rail, and the capacitive effect of this is not to be ignored. In addition to voltage loss in the power supply due to rail splices and corrosion, the two rails act as a large capacitor. If the detectors become too long, it will lead to ghost notifications.

Personally, we use two rings per block, 1 ring per busy indicator.

I want to build a climbing spiral, now what?

Very simple, go to our webshop and order one! Our climbing coils are custom made and laser cut from wood so they always fit exactly and are true to size. It also offers the possibility of lasering guide lines with it, or working with floors for flexible rails.

Floor special for flex rails
Lasered center line for the fixed radius rails

We also understand very well that people prefer to make the climbing coils themselves, as it is a lot cheaper because you now perform the labor yourself. In that case, a few rules of thumb:

Number of suspension points per ring8 outside, 8 inside
Wood layer thickness9 mm
Type of wood recommendedPlywood (MDF warps)
Thickness of threaded endsM8 is preferred

In addition, we choose to hang the rings on rubbers in the studs. For this we use rubber rings and rubber Tulle. This keeps the wood from warping as you tighten the nuts, and greatly reduces noise.

The photos used in this article are of the projects we manufacture in our workshop. To view the model railroads we build on commission click on this link!

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