Helix inside a helix?...

[Ian MacMillan]

I'm getting ready to build 2 helix on the layout and one is pretty straight forward and the other I am just working in my head as it appears that I will need a helix within a helix. Has anyone here done such an item? Here is an overview of the area:



The black trackage is Conrail mainline and the red trackage is New Hampshire Northcoast. The area for the helix, is 4'x'4 not including the shown "tail" where it connects to the rest of the layout.  The helix will be concealed in a mountain.

Now, the first plan that pops in my head is that the CR main line will have a 2% down helix of 44" diameter and then I would have an inner helix for the NHN trackage. going in the opposite direction.

The other idea I had just thought of, but I need to double check the clearances is to put an "S" inside of the mountain to get the NHN trackage heading the same direction as the CR trackage, and then down the same helix. The NHN trackage wouldn't have any cars longer than 50' and locomotives would be 4 axles.



Ideas? Comments? You're an idiot?

[C855B]

Biggest question... construction and service access? Especially with that yin-yang in the middle. If you're planning on hiding it in a mountain, I guess the mountain can be removable, but I see all sorts of access grief with this.

In the top drawing, are you actually designing opposing concentric helices? You do realize, right?... that if you were planning to do maintenance from the inside, the inner helix will block access to the outer helix.

[PRRATSF]

Bear with me on this, its midnight here. Is it possible to move the crossing and wye to the right at all? Going off of your dimensions, your looking at 11" radii on the S turn. By moving the wye and crossing to the right should allow you to eliminate some if not all of the S. Just a thought

Sam 

[peteski]

Ian,
a helix is a huge time-wasting pit while operating a layout. The train goes into the "mountain" and stays there for a long time, while the crew is twiddling their thumbs instead of enjoying running a train.  With the layout of the size you are designing, have you considered unwinding the helix and  exposing the track climbing around the walls of your layout?  That will give the crew a real sense of distance being traveled while on route to the upper level.

Too bad you didn't make to Mass for Tour de Chooch, to check out Rand Howen's layout.  He unwound his helix.  The URL to his blog (which explains the reasons he unwound the helix) is in https://www.therailwire.net/forum/index.php?topic=30748.msg339286#msg339286

[Ian MacMillan]

Biggest question... construction and service access? Especially with that yin-yang in the middle. If you're planning on hiding it in a mountain, I guess the mountain can be removable, but I see all sorts of access grief with this.

In the top drawing, are you actually designing opposing concentric helices? You do realize, right?... that if you were planning to do maintenance from the inside, the inner helix will block access to the outer helix.

The plan is for the helix be open on the inside allowing for you to crouch(ing tiger, hidden dragon) on the inside of it. The ying yang if done that way would be cut out so you could reach up and fix something if needed. Regardless of design the helix would be open on the outside on 2 sides, although its questionable as to how much will actually be exposed. . The helix needs to drop the lines about 10-12"" to the staging yard. So basically: -2" from main line, to 0 sub roadbed, to -3" to clear lowest part of benchwork, to -5" to get proper clearance and hand room. Maybe even to ~8" below the bottom of the benchwork just for good measure.



And just for reference here is what I am getting so far with just rough measurements.


Yes, the first drawing is of concentric helices. I do realize that one would block the other.

Ian,
a helix is a huge time-wasting pit while operating a layout. The train goes into the "mountain" and stays there for a long time, while the crew is twiddling their thumbs instead of enjoying running a train.  With the layout of the size you are designing, have you considered unwinding the helix and  exposing the track climbing around the walls of your layout?  That will give the crew a real sense of distance being traveled while on route to the upper level.

Too bad you didn't make to Mass for Tour de Chooch, to check out Rand Howen's layout.  He unwound his helix.  The URL to his blog (which explains the reasons he unwound the helix) is in https://www.therailwire.net/forum/index.php?topic=30748.msg339286#msg339286

This would not be part of the run as it is coming from staging; you are not traveling from one modeled deck to another. The lower level is staging only as I do not like multi scenic deck layouts. You only run from the end of one helix to the beginning of the other. Once in a helix the computer or dispatcher takes over. A constant climbing "nolix" does not work in this situation as the layout is a big U connected by a staging yard. I do not want any duck unders and only through a scene once so the layout has a helix on either end that brings you to staging.

Bear with me on this, its midnight here. Is it possible to move the crossing and wye to the right at all? Going off of your dimensions, your looking at 11" radii on the S turn. By moving the wye and crossing to the right should allow you to eliminate some if not all of the S. Just a thought

Sam

It can. But the orientation needs to remain the same.

[Ian MacMillan]

I guess also the easiest way out of this would be to loop the NHN trackage in the mountain at 0% until it touches itself and dead end the track. I only really need to stage one small train 

[Ed Kapuscinski]

Yes, do that. KISS.

[conrail98]

Or it could rise up over the CR main as that line goes down to staging so you'd have an extra turn on the helix but it would be the shortline going "up". The other option, is an inverted wedding cake design. Start with the CR main on 20" and the NH line on 22"R and have the CR main go down 1.25" in R per turn. It should take about 5 turns to get down your heigh so lowest level is at 15" radius and would make for slightly easier construction as you'd just spiral out the cuts from one 4x4 sheet of plywood and not have to worry about it's thickness for clearance,

Phil

[packers#1]

Since you only need one train, the KISS method looks like it'd be the best bet; I would assume you would back the train out between each operating session to restage it?

[davefoxx]

Since you only need one train, the KISS method looks like it'd be the best bet; I would assume you would back the train out between each operating session to restage it?

...and the wye is there conveniently to turn trains.  If you need more capacity during ops, perhaps you could add a second stub in staging.

DFF

[mark dance]

I second (and triple) the comment about nasty, long, hidden helix runs to staging even if they are controlled by a dedicated operator.  I favor staging tracks just out of sight and then use helixes to "restage" the staging tracks between sessions ideally from a central storage/fiddle yard location.  This gives the crews the opportunity to finish their jobs by tying the trains up (at a division point for example) just out of sight.  I wrote a sidebar about that in an MRP article a couple of years ago.

A suggestion would therefore be to try and squeeze in as many stub-ended tracks as you can fit at the top of the helix.

md

[cv_acr]

I'm getting ready to build 2 helix on the layout and one is pretty straight forward and the other I am just working in my head as it appears that I will need a helix within a helix. Has anyone here done such an item? Here is an overview of the area:

We have a couple of such scary things at my HO club:



This one gets really scary and somehow manages to have the double track helix that's only half the height of the whole complex end up on the inside:



It also has a couple of other hidden tracks use the same space to make a turnaround. (Since it uses so much space, the philosophy is to put as many as you can in the same spot.) The track the train cars are sitting on isn't technically part of the actual helix.

[kelticsylk]

I know I had seen something like what you are talking about. Trains running on these helixi climb up and go down without leaving the spiral.. This is the only photograph I could find...
http://zscalehobo.com/website/noch/helix.html

Not sure how it was built, but as you can see Koch sells them.

[Cajonpassfan]

http://zscalehobo.com/website/noch/helix.html

Not sure how it was built, but as you can see Koch sells them.

....yeah, one could connect it at the bottom, too, and NEVER come out of the helix, just skip the rest of the layout
Seriously, I'm with Peteski on this, helices are boooooring! I unwound mine and gained a lot of open trackage. I would really think hard about avoiding or at least minimizing the number of turns....
Otto K.

[basementcalling]

When planning my semi double decked layout I chose to stretch the helix out. Instead of a 3 loop helix in one place, I separated the loops. Each is now located at a John Armstrong" blob location. 1 is completely hidden. A second will be 1/3 visible with some tricky backdrop engineering and scenery to avoid tunnels. The third loop is directly above the first, but totally open and will bear some resemblance to Williams Loop on the old WP.

Each is designed so either the front or rear of a typical train will always be in sight, though short locals may vanish for a short time. Even with just a few test runs I can tell I made a wise decision to eliminate the continuous section of hidden track a helix creates. I sacrificed some upper deck locations to do so, but I don't think I will miss them as I have more than enough railroad to keep me happy.

If you have to have a helix, you should strongly consider trying to herniate the beast to leave part of a loop open or use sensors to show train progress through imaginary towns in the hidden portion of the line so throttle creep doesn't become an issue.