Most of the helixes that I’ve seen constructed for layouts spiral in a uniform column circular pattern:
I am contemplating incorporating a helix in my next layout but I would like it to have broad curves > than R30".
My basement area where the layout would be is 10.5 x 18.7’. A conventional column-type helix with R30" curves would eat up a large area of real estate in one corner, which doesn’t appeal to me.
One thought I had was building an “open” helix design that spirals both upward AND outward as it ascends and descends; following the footprint of the layout directly above it, in a rounded triangle pattern. However, I don’t ever recollect seeing any helix designed like this.
Here is a diagram showing a cross-sectional view of how the open helix would look, with the profiles & dimensions of various rolling stock operating on it: (Click photo to enlarge)
As noted in the specs, the minimum radius of the curves would be R31", with the largest R36". My largest locomotives would be 4-8-2 Mohawks, a 4-8-4 Niagara, and a 2-6-6-2 Mallet.
My question for the panel of experts: Are there any inherent issues or problems with an open helix design for ascending or descending to different levels that I may not be seeing or considering?
One plus to the design - as I see it - is that all the structural aspects of the helix are behind the track rather than surrounding or enveloping the track, as seen in the first photo. This allows for easier access and visability of the trains.
One minus would be how close the trains are to each 3" drop-off to the level below it - e.g. in the event of a derailment. I think this could be mitigated using a plexiglas guard rail
I’m having a hard time visualizing the foot print or the advantage?
I’ve designed a numbr of layouts for others using the helix. One of which was a double track continious layout with a helix at each end to access lower lever staging. Scenically it was a single deck layout, so the helixes were completely hidden with scenery over them. Trains went in a tunnel, and down 14" to 18" to a staging yard, then came back up at the other end of the layout.
My new layout incorporates two mini helixes which are only one loop to change elevation in a short distance and increase the illusion of distance. At the end of a peninsula trains enter a tunnel on one side of a backdrop, and reappear on the other side of the back drop at a lower or higher elevation of 4"-5".
Even when I built a double deck layout, which I would never do again, I did not use a helix to get from level to level. I used progressive staggered levels and hidden track behind the scenery.
So I feel like I need more info to understand your idea.
And in any case, I would never recommend a helix of less than 36" radius - forreasons of grade mainly.
Gidday Tom, a helix is a space gobbler, and especially in a small area, having it completely hidden is, IMO a bit of a waste of viewing availability. I think what you’re proposing is completely “doable.”
The only questions I have is whereabouts in your layout space would the helix be positioned, and can it be viewed from all sides?
I say this because if there is part of the helix that can’t be viewed, then I’d be considering stacking the tracks in that area above each other, like in a conventional helix. While the “circle” would be elliptical, it would allow you a slightly larger radius and or a little more edge distance, and while I fundamentally agree with Sheldon as in a large radius, sometimes we must compromise and do the best with the area available.
I know I enter into the realms of heresy, and would be far more generous with the radius and use less of a grade on my own future layout, than this 4%, 18-inch minimum radius helix, but it has the “Look” I’d like to capture.
I think what OP is proposing is a wedding cake style layered helix. The radius gets smaller as it ascends each layer. I don’t see the advantage. My previous layout had a double track (37.5", 40") helix and I had no trouble getting access to or maintaining the helix track/traffic.
I was at the doctor’s office this morning and tried to post the following diagram. Unfortunately, I couldn’t access the photos on my website from my smartpho
The open helix would be directly beneath the upper mainline level so you would only see it from within the upper open area. With 2.5" CTC track spacing, it would be a bit tight for any backdrop and not really serve much purpose.
Thank goodness for ffolkes with a clearer vision than the Bear! [banghead]
Am I to take it Tom, that the helix will not have any scenery as such, just open bench/trackwork? Hence your proposed use of a plexiglass guard, if the clearances are right.
Bottom line, provided that the construction is top notch, I see no good reason why your helix should not work satisfactorily.
Correct, Bear. No scenery - just like a strip mine. [;)]
The only “tight” accessibility would be the 12" wide isthmus - i.e. between the top of the +9" elevation and the bottom side of the upper layout where the mainline is located, prior to the track emerging into the opening. On further consideration, I might need to come up with a way to remove (slide) both sets of #6 turnouts - or the mainline directly above it - should I need to access the turnouts for maintenance purposes.
A very good question, Scott. My initial thought would be a swing gate (shown below), which would require the side with the latch to angle outward for clearance. (Same for the track) I’m not sure how feasible that would be to implement. Sheldon should have some good insight in that regard.
It is a bit of a quandry. I don’t have helix but I do have a semi-circle train elevator that requires crawling under the 40" lower benchwork[%-)] Getting harder and harder to do that and since your helix has is quite solid like my elevator, i’m curious to see what your solution will be.
I guess I would like to see the rest of the track plan and have some better understanding of its scenic and operational goals.
From a simple logistics standpoint what you have on the drawing works.
10 x 18? Is that the total available space including aisle space?
I am considering a swing gate, if built correctly they work fine, there ars a number of well tested examples. But having room for it to swing is the issue I might be having with my layout plan.
Not sure if it isd worth the complexity.
Would getting inside the helix only be a maintenance thing? If so I would skip the gate or a lift out and crawl under.
I am not able to do that at the moment, Sheldon, but at some point I will. What I was primarily interested in is whether there was some inherent problem with an open helix design. Thanks for confirming that the design should work.
Correct. It’s 1/2 a finished basement and it’s nearly twice as long as it is wide. I’m merely trying to utilize the area within the confines of what I have to work with - without turning it into a “spaghetti bowl”.
The maximum height of the basement ceiling in my 75-year old house is < than 7’ (82"), leaving me about 6" of head room. The upper level mainline would be 42 - 48" high. The drop to the staging yard would be ~12" below that, making the lower level 30 - 36" above the basement floor.
I’d like to have access to the inside of the upper portion for maintenance, modeling, and operation purposes. Crawling under the layout is not a problem per say…but it could get old real fast.
The lift outs are very important because my dear wife (and I) need to access the laundry room and there is but one doorway to that. (See above diagram) Therefore, a duck under is out of the question - especi
Then I take it you would never have any hidden staging on your layout? On some layouts the train would and could be out of view as long as (or longer than) a helix.
With the open helix that I’m describing, the trains are visible; it just isn’t visible with scenery. You could also liken it to a gradual grade up a narrow shelf layout; the grade is just concentrated more over one area vs the entire layout - again, w/o scenery.
The upper level will be the showcase for continual running on a double-main and follow the flattish, prototype “waterlevel route” of the NYC. It will also allow the outside & inside mains to interchange with one another at two separate locations; one requiring a interlocking tower.
The open helix also allows movement of locomotives, rolling stock, and passenger cars from the lower staging area up to the mainline. Otherwise, I would need a large yard on the upper level to store my nearly 250 pieces of rolling stock. Given the dimensional confines of my 1/2 basement, I want the upper level to have more of an open feel, with scenery and prototypical structures as the highlights.
I agree that a helix (and a swing gate) would be a learning curve and require precison, as well as the need for fine tuning and adjustment. But experience is only gained by doing it. If I took that approach to my music earlier in my life, I would not have gotten as far as I did.
I think that in Tom’s case, the “helix” makes perfect sense. Given the dimensions of the space and the need to store trains, the OP has no other choice. I would also point out that Tom’s solution to the problem isn’t really a helix, at least in the classic sense of a stand alone spiral. It is more of a gradually rise from under the layout, using the perimeters of a long but narrow space.
