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*** I'm going to use this post to chronicle my progress and ask questions***

A little back story - Some may remember when I first joined the forum in the fall of 2018 I was spouting "My Dream Layout - Phase One - Recreate the the competitive run between the 20th Century Limited and the Broadway Limited. Include the scenic run up the Hudson for the 20th and the "Broadway" and Horseshoe Curve of the PRR.  Include the side by side race into Chicago Union Station. Phase Two - Super Chief and the California Zephyr."

After realizing I would need a football-size room I rethought what I wanted and came up with a two layer setup. The top at eye level is a flat surface within a space of 11'x7'. The base is a oval Helix that supports the top and rises from the floor with an inner return back to the floor.

I've worked out the connections using RR-Tack and can use 72 degree curve on both outer and inner track by inserting a half track at the apex of the outer track. The grade works out to be 1.5 and I was getting clearance of 6 inches. Plan below was done over a year ago. I hit a wall when I started adding layers and couldn't master the software to continue. Fine-tuning to be done. Plus because I intend to have the Helix exposed I hadn't come up with a design on how I wanted it to look.

Green line represents the footprint of track at bottom as it spirals around. At the point where track spirals down I shorten the straightway to have clearance for the inner return path. Reversing that action allows connection at bottom.


Fast forward to today.... I've since added more Locomotives and cars from Ebay purchases. Since I don't have a layout set up to test these purchases I recently sent all of them out all to a local hobby store and had them cleaned and tested. 

What inspired me to get back into this was seeing this portable Helix setup - 


AND this -


The construction of this fits my Tinker-Toy skills.


A comment from another forum - "Stop the video at 4:24 and you can get an idea of how the parts are made. The vertical pieces have two cross members in a dado. They are also secured with what looks like a staple. The plywood sections that hold the track have a tab on the bottom that fit's in the opening of the vertical cross members and captures the track board. You'll also notice the number on the table top. They are used to make sure the vertical members are placed in the proper location. It's a very simple design if you take a moment and stop the video at certain points to get a closer view of the set up."


Another forum that gave me ideas with pre-cut risers -


The intent is to have one train going up as as another comes down in a cleanly designed piece of construction. What ever construction method I use I would be satisfied to see  the gleaming Lionel California Zephyr  and the KLine Silver Chief in my dark basement making the run.  

To complete the picture is a much simpler oval within an oval. The intent here is to run the 20TH Century with PRR. I can use  72 degree curves with the added extra track on the outer or use 54 degree curves on the inner oval. That could be a way to add switches so I can do some "railroading".  It would also allow me to add scenery(buildings and other) between tracks. City scene with my Dep56  collection. I have enough stock to to switch it out and have the circus come to town if I want something different. 

Researching  all this some say a Helix can be a daunting project..... My design goes above that....

Because I'm up against a wall I have to allow access inside of the Helix. I'm thin enough and still able to stoop and bend.... The way I've tackled the issue is to shorten the straightaways at the upper levels so the helix steps back from a corner to allow me to step over the bottom runs(hoping to get 3 or 4 levels)into the cavity created, bend down and crawl under the shorten portion. I'll have cutouts in the upper level so I can have access. I might get ones of those ladders that allow you to lean over if I decide I want more surface for buildings. Either way I think it will work. I'll round off the plywood corners at the front so no one pokes their eye out. 

Random construction thoughts(its all in my head) - On the floor a base in the shape of an oval will be wider then Helix(kick-plate). I can peg or notch the risers into this. I'll paint or stain 2x3 studs for risers. Because I need to support a heavy top I'll have a few 2x4's placed around for supporting the top. Thinking of a steep angle cut from top to bottom for a buttress kind of look. 

I'm using fixed lenght tubular track. My understanding from past questions it won't offer much benfit if I use any kind of padding under track for noise production. Haven't decide what thickness for sub-board. Maybe thin underlayment so I keep my clearance.



Will greatly appreciate any and all feedback. 


Images (8)
  • Helix14: Green line represents  the footprint of track at bottom as it spirals around. At the point where track spirals down I shorten the straightway to have clearance for the inner return path. Reversing that action allows connection at bottom.
  • HelixSample: Inspiration for construction that matches oval shape of my layout
  • Helix15: Pre-built risers
  • HelixPlan1: Visual confirmation that a return inner track can work
  • Helix13: Another option to get secure grade
  • Helix12: My assumption on how to cut risers  to get grade. Tricky perhaps but can't I cut a third riser that is used in the middle with groves on both sides?
  • UnionTAR: Pre-made Risers
  • Helix16: This close-up shows how the risers support the cantilevered turns of the helix.
Last edited by SilverChief
Original Post

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It looks like you intend to build this:


If so, I can't imagine where the rest of your layout (one level or two levels) will go or where you plan to connect the rest to the helixes.  Also, not sure I agree with placing each separate helix on a folding table, and wondering how you plan to "scenic" or "disguise" this mass of lumber?  It might also help to have a more 'fleshed out" plan design to look at, even if the two layers are drawn in pencil and attached as photos.

It sounds like (based on the train names) that your are roughly modeling Chicago Union Station as the center of your empire, with 2 trains running east and 2 trains running west.  AND, you want to model the east bound trains in two of their most famous locations (Horseshoe Curve & Hudson River).  Unless you have a lot more room than your pictures reveal, you're just going to have 2 ovals, one on top of your helixes and one running around the bottom of them?  Is that what you're proposing?

With the space you seem to have, there are alternatives to helixes.  You could do a double track folded dog-bone with one dog-bone end being elevated gradually to be placed above the other (tunneled) dog-bone end on the same side of the layout.  Each track at each of the dog-bone ends could also be made into a reversing loop with a couple of switches and one crossing, allowing trains to loop-to-loop or loop-to-reverse as you choose.

Last comment; are you ready to tear this down if you can no longer physically access the parts of the layout that will need reaching over or climbing under?  Plan ahead and this could be your one and only permanent layout.

All of this is just my 2 cents, so please don't be offended.



Not offended, thanks for the reply. No tables for me, that's a N-Gauge Helix. One big oval only within the 7x11 foot space. Exposed lumber is not an issue for me, its the feature of the bottom half. No scenery other then the look of the helix.  The first run of track will start 2 inches off the floor. The height of Helix will be determined by the Track. Expecting 6 feet or so. Envision it as a table for the upper level. That's were I can play with scenery. I did think of trying to connect top to bottom, That thought will come later after I do more planing. It would give me more operational options. Having two separate is fine.  Not intended to be prototypical. 

Hi Silverchief

When I saw the photos above of those huge helixes, I was reminded of a feature I saw in the modeling media, on a guy who built an N-scale layout in his dining room in the form of a sceniced helix going around the walls something crazy like nine times....much was said about the benefits of having a very supportive wife!  Even in a room of just 7x11 feet, a 2% grade gives a separation of 8" - not much when working in O-scale, but maybe enough if you just want to watch long trains race by.

***It Has A Name - September 25, 2020*** 

I did this a couple of weeks ago. Using cardboard and rosin paper I made this template and laid track down. I found it very helpful to do this. My software plans were off when I started connecting. Taking out the half-straight on the outer track and removing and replacing a few curves on the inside track allows me to fit the layout within  the space I'm able to use. I should be able to get at least 6 levels rising to about five feet before the track turns inward to start the climb down.


In order to create a space that I can crawl into to access the interior of helix I shorten the track from 60" to 45" at about 3 feet. Tight but doable.


Here is how I start the inward curve at top to start the inside spiral to the bottom. Changing a few 72 curve with 54 and adding one 10 inch straight allows me to meet the inner track.


This shows by adding and subtracting track(I have to cut and shorten one curve) I can get the inner track to meet with the outer track at the bottom and start the climb back up.


I could create a staging area within the helix by adding some switches.


The background pasted to wall is about the height of the second level. Flat surface that covers the helix with two  oval tracks and my Dept56 city buildings filling the space. The support post will have an eye-level TV mount at the top portion and where the helix space is I'll mount shelves to hold transformer and other equipment. 



While waiting for plans to be finished I'm doing wall preparation. Scrapping, sealing and painting(white). Purchased a bendable suspended curtain rail that I'll shape to match the oval.  Hoping this will keep dust and cats away...

I have thoughts of painting the support beam to look like a steel beam? Haven't concluding what color to paint the wood for helix yet? Thinking about how to hid the joists and pipes in the ceiling? Perhaps a dark blue sheet stretched over area with lights to depict a starry night? Wiring???

Even though all this helps me visualize I'm still having the plans professional drawn. On the lower half of this layout I'll be using all new Menards tubular track. 


Images (6)
  • AvaTAR_UnionRailRoadOval1
  • AvaTAR-UnionRailRoadGap
  • AvaTAR_UnionRailRoadDownFromTop
  • AvaTAR_UnionRailRoadFromTopAtBottom
  • AvaTAR_UnionRailRoadStaging
  • AvaTAR_UnionRailRoadCity
Last edited by SilverChief

***Super-elevation and My Oval Helix - 27 Sep., 2020***

Because my helix is exposed appearance of the layout is important. The look of super-elevation intrigues me. I've search here and other sites and gleamed enough information that I want to incorporate this into the layout. People have used stiff clothesline or wire which appeals to my budget. I plan on running 6 15-inch aluminium cars with ABA locomotives. The longest stretch between the 72 degree curves is 60 inches. The expected grade will be less than 2 percent.

I'm not looking to run these super fast. My unknowns are where to start the elevation of the outer track. 6 inches back from the approaching curve? 10 inches? With a corresponding lenght at the exit of the curve? Would it be best to compressed the wire or cord at the beginning to ease into the rise?

Any insight is appreciated.

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