Bridges between Exterior Helix and Interior Layout

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Thank you fellows for convincing me to move away from that plastic tube idea I was entertaining.

I next went to that 3" square alum tube that I sliced in half lengthwise to produce 3" channels. These are fine for those 'bridges' that only need to be straight track segments.

But there are a few that need to support curved sections of track. I was thinking of cutting multiple short cuts in their sides that would allow them to bend in a curve. Then I paid another visit to my trusty old metal scrap yard and found some 6" alum channel material. So now my helix bridges are going to be a combination of these 2 type alum channels.

So here is a photo of that 6" wide channel material I found (I believe it is also an extrusion that is utilized in the 'screening' industry). The photo shows a stock piece on the right, and a segmented piece I built on the left,...for one of those curved track segments I mentioned needing above.

That segmented channel above is needed for this very upper loop of helix track that snakes between those upright post of the helix circle to enter back into the layout room.

The two tracks under that wider bridge channel on the top are actually two side-by-side 3" channels (one of them carrying that auto-max cars). Those two 3" channels will mate with a single 6" channel once inside the shed. That 6" wide channel will be a 'singular foundation' for the double crossover arrangement just inside,....originally conceptualized here,..


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History of subject,...

I have built my helix structure external to my train shed,...

I am now cutting the holes in the back wall of the shed that will allow the trains to communicate between the inside layout and that external helix.


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...more history....

What if I decided to try to add two loops to the bottom of my planned outdoor helix to take the trains down to the staging level?

Would it really be so difficult to access if I were to have to get inside the 'hollow helix structure', to fix a derailment of whatever?...and yes I know I will have to at times.

I had a 48" circular metal ring that I placed up on the top of three stacked milk cartons. Why milk cartons,...because it brought the staging track level up to approx the level I was thinking of, So the staging access tracks in the helix structure would be at this level.

Even with this 48" circle I had PLENTY of room to get up inside the helix. Now imagine if my circle is closer to a 60" one (30R helix) I plan on. I am now convinced that I will NOT have to play limbo to get at the interior of this lower helix level.

Hello from the helix



Well-Known Member
Building a metal 'christmas tree' in my helix...ha...ha

I continue to tweak my bridges between the interior layout and the exterior helix. I began to inspect one particular vertical tube that supported at least 3 of the connecting bridges. What modifications could I make that would improve the situations??

My thoughts were if I could cut/trim a notch in that vertical tube in such a manner as to allow the track a bit less curve while negotiating around the tube it would all be beneficial. Rather than cut/trim that tube, how about a combination of L brackets that might provide the 'notch' in the vertical tube? I played around with a number of combinations of configurations utilizing any number of 4, 5, & 6” L brackets. It became a real jig-saw puzzle. I was getting confused with my multiple combinations. I was just about ready to make one particular combination the defining one, when I decided to give it one more inspection.
(didn't take photos of those 'experiments')

On my final inspection I noticed that I had NOT taken into consideration re-bolting the upper and lower connections of the tube itself (stupid me),...bolt that vertical tube to the outside of its support ring, rather than the inside. Then make a pair of those L brackets (actually 2 pair now) the intervening members of the 'continuous' vertical tube.

I have effectively moved that vertical support tube outboard enough to make both the double curves feed the dbl-track helix tracks more gentle in curvature. The single track that branches off one of the helix loop tracks that feeds the center peninsula is more gentle in curvature. The very upper helix loop track is also more gentle.

PLUS, I have discovered a way to make a new bridge structure for the 3-turnout feeding the lower staging area, out of that 6” wide alum material. It will also snake around this latest vertical tube in a more effective manner. I'm building that today.


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I was just looking back at the 'evolution' of this particular bridge feeding the staging tracks.

It started out with these images,..

Then went to this plywood version,..

Wood Roadbed

Tue, 2018-08-21 10:05 — railandsail

Yesterday I cut the entrance hole to the shed a bit wider, then cut out my wood roadbed piece (Its hidden under the paper pattern). I also cut out a square hole for the two Peco under-switch machines/controls to be housed in (not shown yet)

And now it is built of 2 different sections of alum channel,

This bridge deck is now much improved in stiffness and weatherability over the wooden one, and it has guard rails on each side. It also is a much thinner design that makes the underdeck control motors more accessible.

I'm happy with the way this has turned out.


Well-Known Member
Metal Christmas Tree, once again

Back a page ago I posted,...

Building a metal 'christmas tree' in my helix...ha...ha
I continue to tweak my bridges between the interior layout and the exterior helix. I began to inspect one particular vertical tube that supported at least 3 of the connecting bridges. What modifications could I make that would improve the situations??​

I've since made a few other little changes to what I refer to as my metal christmas tree, just trying to 'fine tune' these junctions to the helix curves so as to foolproof them as much as possible. I figure the time to 'get it right' is while I have this greater access prior to installing the circular roadbed and tracks.

latest, larger L- brackets



Well-Known Member
The helix track serving the subterranean staging areas is the larger circle in the helix. There is also a level circular loop of track that begins on that same level, that is inboard of the staging track. The L-brackets that support that diving staging feeder track can not be used to support the level loop of track, so I had to come up with something that would attach to the vertical sidewall post and hold up the inner level loop of track.

At first I thought I might have to affix something to the 'floor piece' of plywood I eventually plan on putting in the helix structure. But the I arrived at a different type of support fixture that would attach to those vertical post and support BOTH the inner and outer tracks,...those white rectangular cutouts glued in place in the photos,...

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