Double Track Helix Question

@BillYo414 posted:

I've been searching for info on the forum on building helixes (helices?) since there's one in my future. Why do I see a recommendation for a double tracked helix all over the place? Nobody seems to really says why you need one but a number of people insist you do. Traffic is the only reason I can see.  Is it that simple?

I'm looking at an 0-72 single tracked helix to travel about 24 inches vertically. The mainline is double tracked but coal drags and passenger service are the only competition I can see for the helix so I feel that double tracking the helix isn't necessary. A train would simply wait until the other passes.

I want to stick to the plan but I know somebody has walked this road before and they might know something that my hubris overlooked.

Susan Deat's layout has Helix's.

I have not built a helix.  The main reason I can see for a double track would be the difficulty in expanding later.  Visually having one going up and one going down at the same time would be impressive.  Sounds like you have a significant plan worked out.

I have @Susan Deats website saved @MartyE haha I have studied her helix work a bit. She's got some clever things going on!

@jhz563 I didn't think of expansion. That's a good point! I won't have much real estate left in the basement for expansion after this though. I also was going to hide my helix. Partially for realism and partially because it will serve as access point and a home for some electronics. Big Boy 4005 had a covered helix similar to what I'm building. His was inside the layout and mine will be concealed by a mountain/coal mine on the layout facing side.

The only reasons I can see for a double-track helix are to be able to go up/down the layout without the need for reversing loops and to save space vs having a 2nd helix. If you just have 1 single-track helix, you need a way to get back to it on both levels, hence the need for reversing loops that might limit your design options,

Beautiful! @DoubleDAZ I have reverse loops covered.

What do you mean by the indexing? @Tom Tee And also the easement. What do you mean by that?

Love the idea of a helix, just can't imagine how I could have fit one in and still had a workshop!

Mine actually fits under the table of the layout. Train goes into the mountain on the top of level and comes out on the lower level. I definitely don't have any space for a helix outside of the layout it would be more convenient but it's not possible.

A helix does not have to be a circle.  It can be oblong thereby allowing smaller curves to a point.  The one in the picture illustrates this idea.  This one was built decades ago and is not a model of good design, but illustrates something other than a circle.

Here's a sample O-72 Helix with a 24" rise and 6" separation done in SCARM. The ovals are offset using 5.5" tracks for clarity and ease of editing.

@DoubleDAZ posted:

Here's a sample O-72 Helix with a 24" rise and 6" separation done in SCARM. The ovals are offset using 5.5" tracks for clarity and ease of editing.

It's easy to draw them in a layout program, it's the building of them that is challenging!

I gotcha @Tom Tee I have plenty of easement built in. I learned not to make a sudden elevation as a kid. No problem.

Bill, here are two reasons my helix is double tracked:  The inside has two sidings for consists.  It's just as easy to build a two track bed in the large space that the 10' diameter outside track required.

The above photo is on my web page, Four Level Track with Helix Access

I think helixes can become a little bit of a bottle neck for operations; especially a single track one. It does take some time to traverse one. I've only seen them on local HO layouts but all of those have been double track. FWIW.   

Jim K

I can see the benefits of the double track. I'm going to see if the track plan can be modified to squeeze a second track on there but the helix is squeezed in there as it is.

Given that my layout focuses on steel mill operations on the top level, the helix is only used to move coal hoppers to and from the mine. But I'm going to be hurting if I want to run mixed freight or passenger service.

@BillYo414 - Have you seen the HO scale Helix platforms for sell on the bay?  I saw one today and immediately thought of you.

I have not. I was planning to just use the wood and threaded rod with nut adjusters. My greatest concern is actually just string-lining the train with a live coal load. That would be damaged equipment AND a mess.

A helix would be super cool, I only wish I had space to do one.

@gunrunnerjohn posted:

A helix would be super cool, I only wish I had space to do one.

You haven't gone down to the floor yet!

@jhz563 posted:

You haven't gone down to the floor yet!

Yeah @gunrunnerjohn, I see your layout has one level haha plenty of room up and down. My helix is actually buried under the table. That's the only way I have the space. It will likely be 0-72.

@jhz563 posted:

You haven't gone down to the floor yet!

I'd run into all the boxes of stuff stored under the layout!

I'm late to the party here, but I do have experience with helixes in a couple of scales.  Things to be careful about are spacing between levels (which in turn determines the grade) and length of run (and thus time the train is in the helix).

In your case, an O72 helix will have a run of 226 inches.  For 6 inches of separation (railhead to railhead), the grade works out to 2.65% which is not too bad.  It will seem like a 3% grade or even slightly more to the locomotives, since the entire train will be on the O72 curve.  The 6 inches is top of rail to top of rail.  If you use 1/2" plywood with Gargraves, Ross or Atlas track on top, the clearance from top of rail to bottom of plywood overhead is more like 5 inches.

A 4-turn O72 helix has a run of 904.8 inches or almost 75 and a half feet.  At 10 to 20 scale mph (good helix speed), a train should take between 2 and 4 minutes to run the helix (again not too bad for a train waiting its turn).

Our Train club has a 4 track HO Helix.  It's about 6 feet across at the minimum and rises 6 feet.  Circles over itself about 7 times to get the elevation.   The people who made it at the club used plywood cut in arcs and used long pieces of 5/8 threaded rod as supports.  Probably around 20.  That way they didn't have to be exact with their starting level and the finished level.  Used a nut under the plywood arc and on top.  To fine tune for the elevation drop and raise they adjusted the nuts up or down to get everything smooth.

@Bob I have mine coming out to a grade at 2.4% according to AnyRail I think. I haven't messed with this in a while since the helix won't be underway for a while yet (like a year). But I'm not overly concerned about time in the helix since there won't be a ton of traffic between levels. Coal drags will be the main traffic. Perhaps I'll grow to regret this opinion? I do plan to have a window in the side so I can see what's going on.

I was actually planning on using tubular track to save some money. Any reason not to? I was going to split the rails on the bottom and crimp the wires between it to make darn sure the continuity will be good.

4 turns would get me the height I'm considering so less than five minutes is perfect for me.

@Dan65train this sounds very similar to the design I was to use. I'm only concerned about making sure I don't clip the rods with locomotive and long car overhang.

Here are some photos I took of a helix at Roundhouse South in 2016.  Check their track supports.  Charlie

I was actually planning on using tubular track to save some money.

I wouldn't use tubular track. Too many joints that can cause electrical problems in the future. Thats the last thing you need is a poor electrical connection in the helix and then try and fix it. I would use Gargraves flex track, you would probably cut down about 2/3rds the number of connections you would have.

Now, that's a HELIX!   The blue lights are interesting...

@Yardmaster that's a good point. I didn't think of it like that. You don't think making the extra connections under the tracks would help?

@Dan65train that's almost exactly what I plan to do. Thank you for sharing!

You will still need extra power feed lines in the helix, but what you are eliminating are future headaches by using flex track.

Dan,

How does the club reach anything if there's a problem on that helix?

@gunrunnerjohn  The lights almost look like "black" lights.

@cpowell The bottom level is about 4 feet off the floor. You just lift up a curtain section and crawl into the center.  You can stand up inside without a problem. 

Also,  at the bottom of the helix where a train usually descends there is a long straight away @ 20 feet long. I know that a helix is a very good test for long trains for finding that weak coupler you never knew you had. Watching 15 freight cars cycling faster and faster to the bottom with the loco still gradually ascending to the top is something you don't forget.

Admittedly, I have been away from the forum for a while, but read it at least weekly.

This thread caught my eye, and reminded me of Elliott aka Big_Boy_4005 fantastic layout:

Alex

This was a display I did a few years back with my helix.  A few months later our club lost our space.  I was able to keep the double helix but the one in front was trashed. ( only the lumber)

@BillYo414 - You need to think big and do something different from all the helices that have come before.  Why not do a double helix or even a triple helix?

@Ingeniero No1 posted:

Admittedly, I have been away from the forum for a while, but read it at least weekly.

This thread caught my eye, and reminded me of Elliott aka Big_Boy_4005 fantastic layout:

Alex

His layout is a major reason I think I can pull off the helix just fine. He has a bigger helix than what I'm aiming for PLUS entry and exit points along the way. I'm just looking for a single track helix between 16" and 24" high. If he can accomplish that, then I can accomplish what I'm setting out to do. Susan Deats is another source of inspiration. I think I'm going to do just fine when I get there.

@boomer0622 how often do you have operating trouble with that double helix? I keep hearing how inconsistent trains are in helices but I have my doubts about that because they're still used.

@A. Wells I'm considering upgrading to a double helix. It's just a matter of space. I have it pretty cramped on the top approach.

@BillYo414 - Just to clarify, I don't mean two separate helices.  I mean a real double helix (think DNA).

@A. Wells posted:

@BillYo414 - Just to clarify, I don't mean two separate helices.  I mean a real double helix (think DNA).

You're killin me smallz haha

The only operating problems I have had is trying to run large steam engines and that was only because of uneven track.