I have been thinking about making my next layour a multi-level layout.[:)] Some may say that this is jumping the gun for there is no reason to move or tear down what I have but it the day will come when the process of building a new layout will begin. The multi-level layout has been a fascination for a long time due to the possibility of long runs and twice as much scenery in the same space. Modeling in Ho makes this a very attractive method of design.[tup]
With this said I would like to ask the vast knowledge of forum members what their experience with helixes are. What is the grade, radius as well as building methods used? What are the biggest issues in operating a helix, ie operation going up the helix and coming down the helix with 30 to 40 car freights?
I have searched this forum and in my opinion an octagonal helix construction with ready rod will be the way to go with 4 inch seperation between track and uppper underside of plywood of next level. The radius would have to be at least 30" to keep the grade reasonable. [:P]
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:
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.
I’m with you all the way, with twice the modeling afforded by two (or more) levels. I’m sure this can get congested with a number of operators in the isle, but worth it.With that: I’m doing a two level……But I only have the upper level somewhat operational! I do however, have the helix operational and this years construction season will hopefully see trackage on the lower level from the helix to off pike staging. In a quick overview: My layout is an around the walls with a peninsula and the helix takes up the end of the lower level.The helix is a 5-1/2 (close to 6) turn with an “S” coming up through a cut on the upper level of the peninsula. It is of a twin track design with 4” separation (2% grade, give or take a bit) and of 30” radius.The trackage here is the mainline connecting the upper and lower level off pike staging (also has a reversing loop in staging for turning a train or a continues run option) with junctions connecting the short lines. The shortlines have all the activity as peddlers.I can’t address the length of trains you talk of, as even my mainline runs twenty cars max with the shortline running ten and the logging line maxing out with about six.What I can tell you; is I do run trains, using the helix as “lower” staging, on the helix and that
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.
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.
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.
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.
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)
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, you are quite right in that their is a distinct possibility of stringlining (centripetal force) if the bank is increased too much. However, I’m sure you’d agree that banking inward is certainly preferable to banking outward. I have been running 15-20 car freights lately and have never had a stringlining issue on the helix. Still, I’d be interested in hearing what other people have to say on this issue as well.
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
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.
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.
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.
One thing I have noticed with the posted helix designs is they are supported from the ceiling. Not sure I’ll be able to do this. Will this make the all-thread method obsolete?"
