Who has a Helix and what are your experiences

Hey Frank.

The multi-level layout sounds like a great idea. My layout varies anywhere from single deck to triple deck, and now I wish I had squeezed out some more room with even more multi-level.

I used the same design that you propose to make my helix. It's a five-turn, single track helix on a 32" radius with 3.5" top-bottom separation. I found this site extremely helpful when I built my helix. Scroll down to KCT Helix and you're all set:

http://www.bnsfchillisub.com/Local%20Layouts.htm

That plan uses wedges that are double layered and staggered to create the subroadbed. This system is quick, uniform, and economizes lumber. My helix structure was done in about a weekend.

Since you want 30-40 car freights, keeping the grade down should be your paramount priority, even if it means increasing the radius by a few inches or reducing clearance. I'm not sure what equipment you are running, so check your rolling stock and see what is the real max height you need. If you are running any double stacks, you will absolutely need those 4". The tallest cars I will be running are thrall autoracks and extended height paper service boxcars, so 3.5" was perfectly fine for me.

Frank:

 Nice link to that helix.

Your plans for the helix are sound.  The club I was previously associated had two helixes with octagonal frameworks and threaded metal rods supporting the plywood roadbed turned out well.  Remember to lay, test and debug your track as you construct the roadbed.  Fixing the track after completing the helix will be tougher.

Keep in mind that, everything else being equal, a multi-deck layout needs wider operator aisles than a single-level layout.  On a multi-deck layout, people may need to step back from the layout edge to view the lower deck.  Also, there are likely to be more operators.  Previous advice to not stack busy areas to avoid operator conflicts is also good.  However, one can design the "town" areas  (places of concentrated trackage) so that operators work mostly from opposite ends of their respective areas and thus minimize the problem.

Mark

Just a thought relating to the helix I had linked earlier and really a minute detail at the conceptual stage but important at the construction stage:

Consider placing the metal support rods on the inside of the trackage. Doing this helped me enormously. Since you are only supporting the track on one side, the subroadbed is likely to bend somewhat in either direction as you go up. Placing the rods on the inside caused the subroadbed to bend inwards, creating a nice superelevation and helping with any tracking issues. Rods inside places the track further out instead of in, increasing radius and thus reducing grade. Also, having the rods inside means that junctions anywhere along the helix are much easier to build without worrying about the rods getting in the way. That was particularly important to me as there are 3 intermediate junctions built into my helix, not including the top and bottom. Anyways, food for thought.

Use rods in pairs, one each on either sides of the roadbed!

Mark

 Hi,

Thank you Railroadyoshi.  Your information is very valuable and greatly appreciated and the Chili sub layout is a wonderful website-thanks.  The only question is how much wider would the wedges have to be to allow for double tracking?  Would you have any idea?  Your information would be greatly appreciated.  Here is a site that I was looking at which is in german but even without a translation program it is easy to understand what is being talked about. http://www.modellbahn-online.de/inhalt/tipps_wendelbau_fertige_berechnungen.php?rubrik=tipps

Just to clarify quickly R stands for Radius and D for Diameter.  It is easy to apply some calculations and get the size of boards needed for any radius and also double tracking.

Thank you colvinbackshop.  Those are great suggestions that you have made.  They will certainly be kept in mind when the building starts.  Information like this is invaluable for layout building and which is what makes this forum so great.

Thank you markpierce.  That is great information. Got to thinking with two rods opposite of one another it might be possible to create superelevation.  Also using threaded rod enables one to change the elevation between tracks and grade quite easily.

Looking forward to being able to start building and correcting the issues from what I have now.  Each layout is a great learning experience.

Thank you

Frank

How about double helices? Do they count?

I use a helix to get trains up and down from hidden staging.

If your helix is going to be hidden, make sure you make the outer scenery removeable so you can access all points. I use velcro strips to hold sections of scenery in place in certain strategic locations.

The only operational problem I've ever had (apart from occasionally getting too ambitious about how many cars can be pulled uphill by one loco) is the rare runaway caused by two couplers letting go of each other.

You want to make sure you have lots of padding below the helix, just in case.

Howdy, Frank,

If you enter helix AND Brunton in the search box and select Model Railroader Forums, the first link that comes up is the Mother of all Helices - six full turns, and up to 4 tracks wide!  Not only that, the builder has provided a link to his site - and a photo clinic on how to build it.

Granted that, as built, it's probably gross overkill for most of us.  The construction techniques are valid in any scale and for any helix configuration.

Chuck (modeling Central Japan in September, 1964 - with two planned single-turn helices)

railroadyoshi

Placing the rods on the inside caused the subroadbed to bend inwards, creating a nice superelevation and helping with any tracking issues.

Intuitively, I don't think you would want to superelevate the helix curves.  Superelevation, or "banking" as we know it from automobile roadways, is designed to counter centrifugal forces which push things to the outside of a curve.  This is mostly of concern at high speed, as the force increases with linear velocity.  At model railroad speeds, superelevation is more a modelling fine point than an important physical consideration.

If anything, a helix will have the opposite problem.  Here, you're pulling a lot of dragging weight behind the engine, going around a curve.  The typical failure mode here is "clotheslining."  The forward pull of the engines combines with the reverse gravitational pull of the back of the train, and the cars in the middle tip inwards and fall off the track to the inside.  Since superelevation also tilts the cars inward, you're setting yourself up for this kind of accident.

Having never built a helix myself, what do experienced modellers think?

MisterBeasley

railroadyoshi

Placing the rods on the inside caused the subroadbed to bend inwards, creating a nice superelevation and helping with any tracking issues.

Intuitively, I don't think you would want to superelevate the helix curves.  Superelevation, or "banking" as we know it from automobile roadways, is designed to counter centrifugal forces which push things to the outside of a curve.  This is mostly of concern at high speed, as the force increases with linear velocity.  At model railroad speeds, superelevation is more a modelling fine point than an important physical consideration.

If anything, a helix will have the opposite problem.  Here, you're pulling a lot of dragging weight behind the engine, going around a curve.  The typical failure mode here is "clotheslining."  The forward pull of the engines combines with the reverse gravitational pull of the back of the train, and the cars in the middle tip inwards and fall off the track to the inside.  Since superelevation also tilts the cars inward, you're setting yourself up for this kind of accident.

Having never built a helix myself, what do experienced modellers think?

  I have been involved in a number of helix construction projects.  The current one was 2 years ago for our club.  A 5 turn/double track helix in HO.  It uses 3/8" threaded rods and plywood with a constant 2% grade.  The double track is Atlas code 100 with  33" and a 36" radius curves.  The helix works fine, but like all helixes:

• You need 'power' to get a train up them(even on large radius/low grade ones).  3 Atlas/Genesis/Kato engines will handle a 25 car train of NMRA weighted cars up the 'hill'. 
• Going down the helix is the tricky part.  The train really 'pushes' the engines and if they have any slop in the worm gear, you will set up a 'surging' action. 
• Also, operation must be slow and deliberate when decending. 
• I cannot imagine operating on a 20" or 24" radius helix that I have seen in some track plans.  The grades and the compensation for the sharp curves will really limit what can be operated.
• Another thing is the amount of track in the helix - many times there is more distance in the helix than in the 'on stage' part of the layout!

  I do not want to sound negative, but unless you have the space to construct a big helix you are better off thinking/designing on a single level track plan.  I have a 20' by 25' layout space and can afford to build a helix - but did not due to the above issues.  A friend had a complete single level(entire basement) layout he tore down and planed to build a two layer layout with a helix.  After constructing/operating on the club layout, he wound up with a two layer layout that is not connected.  He has modern trains on the upper level and 'transition era' trains/bldg's on the lower level(both have staging).  In his case, he wanted to model two different era's and the space to put in the helix was not justified in his view.  An alternative to a helix is the 'nolix' that wraps around the entire layout to get between the levels.  The 'nolix' seems to work very well with 'mushroom' style track plans.

Jim Bernier

Having built a nolix to connect lower and upper decks over 40 years ago, I say "go nolix."  However, it is easier to construct if only a part of the layout is multiple deck.

Mark

Good points Jim.

I too had a helix on my last layout and now will never do it again for the all the reasons you listed.  Most important among these was that there was twice as much track in the helix as visible on the layout.  I quickly grew weary of waiting (and waiting and waiting) for the train to come out of either end of the helix.  My recommondation would be that unless you are going to gain so much layout that the ratio of visible to helix is 4:1 to 8:1 I would give it a miss.

 Dwayne A

da1

I quickly grew weary of waiting (and waiting and waiting) for the train to come out of either end of the helix

Don't forget that you can lessen the pain by "herniating" a loop or two of the helix. Still, a helix should only be used on larger layouts.

Karl

Here's the helix on my layout that Chuck (tomikawaTT) referred to earlier:

Here's a link to my construction description on my website: http://www.thecbandqinwyoming.com/CM%20-%20Behemoth%20Helix.htm

I recently did a clinic at the NMRA Mid-Eastern Region Convention, where I talked about major helix design considerations, including stringlining, time the train is out of sight, grades and radii, footprint, etc. I also have a formula regarding comensated grades (grades on a curve). It's a Powerpoint presentation - I hope I'll be able to get it posted on my website in the next month or two so anyone with Powerpoint viewer can see it.

I built my helix during the 1987-88 period and would not replace it for anything.  The layotu is 35ft by 28 ft, and is three decks.  The helix leaves the top deck and carries a single mainline around 2 looks of 38" radius main to emerge  behind a hilly area on the middle deck.  The main then winds around the middle deck, dropping slightly as it moves to the major terminal on the middle deck.  The helix roadbed and track were laid to be bullet proof and here in 2008, they still are.  I had one derailment in all that time.  There is an opening in the facia that allows a crew to check progress of the ascent/descent.

The middle deck then goes down to the bottom deck on a long, descending grade that is hidden from normal view, and arrives on the bottom deck from between some structures.

I like the helix and recommend it.  The helix sits under the Oklahoma City/Flynn yard complex on the top deck and has very good access.  that is my exprience, and if I were to rebuild/build a new layout, it would very likely have a helix as part of it.

Bob

Don't despair.  The rod hangers can be supported by vertical framework rising inside the helix.  I've seen it done twice first-hand.

Mark

Here's proof for your eyes.  There is probably more track in this helix then the total of most home layouts.  This helix serves three deck levels.

Mark

Loco,

  The helix at our club layout uses 3/8" threaded rods that start at the bottom of the helix.  They do not tie into the ceiling.  We used 3/4" plywood for the base of the helix, and a double layer of 1/2" plywood for each 'turn' of the helix.  Nuts/washers hold up each of the turns(5 of them).  I am sure the helix is 'over-built', but we had the materials and it is complete.  No problems with it other than new engineers stopping in the middle of the helix when decending.  We now have a 'rule' that there is a complete 'lineup' of the turnouts from the junction wyes at the top - all the way into staging, before a train starts it's decent.

Jim

We have several helices at my club connecting sections of our very large club layout over multiple levels. (ie, why stop at two?)

 Our general construction method is to build a solid, level base with 3/4 plywood, and build the helix using 1/2 inch plywood for the turns and wood blocks as spacers. We've found it much easier to get consistent spacing using wood blocks cut to indentical sizes than to fiddle with the threaded rods.

Also, in several cases, there are tracks heading in opposite directions around the helix - since helices do take up space, we try to economize by putting more than one into the same space, and sometimes they turn in opposite directions, which slightly complicates things, as below:

http://www.wrmrc.ca/layout16.html

http://www.wrmrc.ca/layout11.html

http://www.wrmrc.ca/construction17.html

 Hello everybody,

thank you for taking your time to reply to this post.

R.T.Poteet,-a double helix would count as well.  That is what I will build,a  double tracked helix.

Craig Cooper-your suggestion of scenery that is easy to remove is great and will be kept in mind for the future.  Great suggestion.

timikawaTT-yes the first thing I done was search for helix on this forum and read the posts and seen the beauty from Mr. Brunton.  What a beauty.

MisterBeasley-you have a very valid point.  It would be an idea to superelevate the tracks inward used by the trains going down hill and the superelevate the tracks outward going up the grade.

Yoshi-thank you for the input.  What grade and radius do you have and what kind of power do you need to pull a 20 car freight up the helix?

jrbernier-thank you for the valuable information.  It gives me a lot to think about regarding the Pros and Cons of a helix.  Since I am operating in DC I would have to install some light sensors that would switch diodes into the circuit to decrease the track voltage by .7volt to slow trains down going down the elevation.  

markpierce-what is a nolix, an oval helix?

Dwayne A-interesting experience, will have to look up some clubs that have a helix and talk to the members.  There is the http://www.wrmrc.ca/links.html that I should talk to before building.  Their layout is on 5 different levels.

Karl-great point and will look into it as well.

Brunton-love your helix and also the re-railers are a great idea.  How is it working out for you?

Pastorbob-interesting experience.  It seems like it depends on the persons perception if the advantages and disadvantages of the helix.   The plan is to build the helix in such a manner that it can be re-used on future layouts.  Out of curiosity what are the elevations of your layout?

Loco- I have seen the rod hangers support the helix from up above and below.  If you use 3/8 rod it should be fairly sturdy either way.

cv-acr-You guys rock.  Seen your layout a few times when you have open house and loved it each time.  Hoping that the next time you have an open house my work schedule will allow me to come for a visit.  Have a number of questions for your guys.

Loco-when there is the next self guided layout tour in 2009 it is a real treat to see the http://www.wrmrc.ca/links.html layout in operation.  It is the Double Header self guided layout tour in the Kitchener, Waterloo, Guelph, Cambridge and surrounding area.  Well worth a visit and worth the tank of fuel and low admission.

Thank you everybody for the replies.  Hoping that by summer next year the construction of a helix can begin.

Frank 

Frank,  Imagine a helix stretched out straight, with the grade. Thats a nolix. It would be a track that goes up/down grade a long enough distance that its able to join onto the upper/lower deck.

Mike

Here are two construction photos of a nolix. It does curve around to the left at the far end (of the lower image) and makes a five foot diameter loop at the near end. Over twenty feet long all in all. Addl. photo at bottom of this page, and from another angle here (scroll down).

It came out really nice once the scenery at all three levels was complete.

Karl

Iarak: beautiful "nolix". 

Another advanatage to the "nolix" -- its prototypical.  The old interchange track between the old (former? ex?) Rock Island and the old (former? ex?) Illinois Central in LaSalle, Illinois is still used by IAIS to move carload cement to and from the two-track yard in the east end of LaSalle.  (The cement company's un-numbered GE 80-tonner then moves the cars across the Illinois River, to and from the cement plant in Oglesby, Illinois).  One example of hundreds of such "nolixes" in existance and in usage today. 

Iarak: Thanks for sharing your great layout.

wccobb

Iarak: beautiful "nolix". 

Thanks for sharing your great layout.

My pleasure. It's a work of passion (and a work in progress) like most of our layouts. I have learned a lot from these forums (still do) and am happy to pass it along.

Karl