You are at it

Randy, I am not in a position to calculate out the math part for you, but if you are running 89' flat cars "TOFC" then I would not recommend going anything less than where you are presently. Personally my layout has a 30" min radius and I do not feel comfortable running long equipment on it. It will run, but it also hangs over so much that it looks really bad, tracking can be an issue on curves and you have to keep the shrubs and trees back from the right of way. In a helix the main issue is you are not pulling a train up the rise 2 1/2" you are pulling the train up 2 1/2" plus the drag compensation of going around a curve. the tighter the curve the larger that compensation has to be. Pulling long cars around a tight circle is going to want to make the long cars stringline and pull to the center and off the layout to the floor.

Look at other solutions or backdate your railroad to 40' boxcar era!! Sorry

First the bad news....

According to a great article written by Joe Fugate back in the issue 1 (January 2009) of MRH. The radius ratio for "most equipment to track reliably if everything is similar length" is 2.5 and for" all equipment should track reliably" is 3.  This means that if a car is 12 inches long (like an 89' TOFC), then the radius should be between (12 X 2.5) 30 and (12 X 3) 36 inches. To look good the radius should be even bigger.

I am assuming that by 2 1/2 inches spacing, you mean from the top of the track to the bottom of the above support.  So the rail to rail height will be about 3 1/4 (2 1/2 + 1/2 plywood + 1/4 for approximate track height).  A 2% grade (the max I would use) would require a (3 1/4 divided by 2%) 162.5 inch run. This would require a (162.5 / 3.1416 / 2) 25.8 inch radius.

Now for more bad news. Your spacing of 2 1/2 inches is very tight.  I would greatly consider 3 1/4 inches minimum. NMRA classic height standard is 3 1/32 and modern height standard is 3 5/32.  Therefore the rail to rail height should be about 4 inches min.  4 inches height would require a (4 / 2%= 200"run / 3.1416 / 2) 31.8 inches radius.

So this basically takes you right back to where your were.  You stated that our inside track has a radius of 29", so your out side track radius should be around 32".  This is what I would stick with.  You can run the longer stuff on the outside, and/or use the out side track for going up and the inside track for going down.

Sorry I wasn't clear on the spacing...

The 2 1/2" spacing is my center to center spacing between tracks.  I forget exactly what my track to track vertical spacing is and my plans are on my home computer, but it is about 4". Moving the furnace is looking better and better. 

thanks

Randy

"Moving the furnace is

Instead of moving the furnace can you shift the helix 4 inches away from it? ........DaveB 

I wish it were that easy

I have an aisle on the other side of the helix, so moving that direction is not good. If it weren't for that, there really wouldn't be much of a problem. My aisle went from being a little tight in the corner, to being really, really tight in the corner. As it is, I should have about 15" back there, which isn't good, but isn't necessarily the end of the world as it is a spot where only one operator would be at a time anyway, but I sure liked it better when it was closer to 25". That siding may become known as Fat Man's Misery.  

Randy

2 tracks?

Randy, can you convert the Helix into a single track?

"I have an aisle on the other

Maybe you should consider how you'll get in there to maintain or replace the furnace when it becomes necessary? Perhaps the helix could be shifted to a less crowded part of the room? or replaced with a train elevator that fits along the wall?  .....DaveB 

2 tracks

I'm open for discussion on the topic, but here's the situation.  I have two railroads, the B&O and the PC, they ran parallel in my area for the most part.  I want the helix to be operationally "invisible" as much as possible, therefore I chose to have an up track and a down track for each railroad, which totals four tracks.  Wait, that's not all, I also have an inner track that gets the B&O from staging to the West end of the layout.  So, I have a five-track helix planned.  There I said it.    

I really don't like the thought of trains waiting for another train to get out of the helix, and it just seems like it could be a huge bottleneck without all those tracks. I may be wrong and like I said, I'm open for discussion.  

Randy

helix plan

Randy, can you can you post a detailed plan of the helix area?

Furnace and elevator

I can get to the furnace from the other side and the front. The water heater is over on that other side, but I could probably move the furnace about 8" fairly easily, some ductwork changes. Moving it farther would be a bigger project. The helix pretty much has to be where it is without a complete re-work of the entire plan, and I don't think it would work out with it any where else. 

The elevator is an intriguing thought, but way too complicated electrically for me to take on. It would have to be big enough to hold about a 20 car train and stop at three different levels reliably. I see derailments in my future down that path, and I hate derailments with a burning, vitriolic passion. I like that outside-the-box thinking though. If I had any confidence in my ability to build one that would work perfectly, and do it in less than a year, I might try it. 

Randy

Helix area...

The furnace is immediately to the right of the monster helix from outer space shown below. The aisle in question is in the corner on the left.   

Lower level staging...

This is how trains get from the lower level staging area up to the second deck, via the innermost track of the helix.  

concider oval to keep grade down and keep isles space

I made a test helix in HO useing two tracks ,outside 29'' dedicated to uphill inside 26 1/2 " is down , 3 turns  to second level BUT not round made it OVAL using 12' straites on each side ( one side incorporated rerailers) code 100 sodered NO turnouts, transitioned back to code 83 at entrance/exit., thumb- tacked down to allow movement (screws and washers would be prefered )

     Tested with wathers passenger cars ,went so well I put a wrapper a round it (masonitte sides) and and called it done , I have never had an issue in the helix except for rare coupler seperations due to kadee look alikes , ... gradent is mild at a tad over 2%  ... NOTE ; I use 1 long and 1 medium " whisker "at every connection point on my 85 ' walther cars,  30 " is the default radi on rest of railroad, and car spacing looks OK ..

       I continued the grade outside the helix for what would of been another turn to get my deck seperation and to reduce the the disappearing act . I would not have a problem doing again, though I would use better construction technics ,but mine started as a test and the old" if it ain't broke why fix it "thing came into play .. jerr

Curves add drag

Oval is a good idea...

Making it oval would be a good idea, except that I have a peninsula about 34" away from the top of this helix, so I can't stretch it that direction. If there is an open spot in this room, it already has tracks planned for it. That's why I thought about trying to shrink the helix in size, or perhaps in number of tracks.  Thanks for the idea though. 

Randy

reduce your track count

reduce your track count too three, 1 for each railroad plus the one up the middle, and you should regain all of the space you are missing. Yes I means no passing in the helix unless you put crossovers in the helix to allow each railroad to use either side of the helix. I can see the collisions already

Seriously consider 1 track in the helix for B&O and 1 for the PC with no crossovers.

If you go from 2.5 inches

If you go from 2.5 inches center to center to 2.25 you will pick up some additional room. I would also go with fewer tracks. Even if a train has to wait to go down the helix or up. A signal causing the train to wait would surely be justified, and lots of trains had to wait on the real railroads as well.

Your smallest radius is 29 inches which is tight for long equipment and long trains. Using your 2.5 spacing, you end up with 31.5, 34, 36.5 and 39. If you find a way to use 2 tracks to accomplish your transit from one level to the others and used 34, and 31.75, you end up with better grades and can widen the isle by about ten inches. 25 inches is still tight but better than your 15 by a huge amount. Also on another thread one individual claimed to use a smaller radius with negative super elevation and that it was trouble free. That would mean making the inner rail a bit higher than the outer rail in the helix.

Going with 2 tracks instead of 5 will save you lots of money on track and turn outs as well as looking better where they go into the mountain. Think of each lap in your helix needing 5 sections of flex track and at least 4 layers between layers not counting turnouts or crossings. You just saved at least 60 sections of flex track and likely more like 75 by going to 2 tracks, track that likely would all be hidden. Tunnels are expensive in the prototype and I do not recall seeing 4 track tunnels or 5 track tunnels in the prototype, two different lines with single track tunnels, one each would look better as well.

The only place I can think of where I saw lots of trains and multiple tunnels for up to 4 tracks in close proximity was the area of horse shoe curve, but I think in your era it was cut down to three tracks and one of the former double tracked locations was turned to single track so as to gain vertical clearance.

"reduce your track count"    

I like the idea of fewer tracks...

I would surely like to reduce the number of tracks for a variety of reasons, but I've been worried about waits at the helix.  I think of a helix as sort of a necessary evil, and wanted to make it as unobtrusive as possible to operations.  I hear horror stories of people complaining about how long it takes to get through a helix, and then to add waiting for another train on top of that just really made me nervous.  

One track for each railroad, eh?  

Randy

How many turns is the helix?

One track for each direction

How about one track for each direction.  Outside track (larger radius) up and inside track down.  Joint trackage rights and trains from both lines could queue up behind each other for the trek to the next level.  The occasional wait for crossover opposing traffic (at an interlock) at the entrance/exit should be tolerable.

Dave

One for each direction

This is a good idea. the tracks could converge just out of sight, if you don't like the appearance of shared trackage, and then you only need to wait until a train is 1/2 way down before you could follow it in.

 "the tracks could converge

"the tracks could converge just out of sight, if you don't like the appearance of shared trackage, and then you only need to wait until a train is 1/2 way down before you could follow it in."

Yeah, Since a helix is off scene anyway the shared trackage should be out of mind. A little waiting for trains to clear is good for operations since layouts don't have long enough runs anyway. I'd also examine the track density of the whole room since having no other possible place for the helix implies too much track everywhere else? ....DaveB

Some answers...

Deck separation from lower staging to the first deck is 12", between the two visible decks is 18", but I have room to do some climbing outside of the helix so both helices will be about three turns. 

Having shared trackage with one track being up and the other down doesn't sound too bad.  You can't really just follow a train once its half way up or down though, because the two railroads will have to cross over each other at the top and bottom of the helix.  So you would have to let a train in front of you traverse about half the helix AND make sure no train from the other railroad was going to be in those crossings.  That bothers me a bit because it is totally non-prototypical for these railroads.  They didn't have to worry about each other. Should I be worried about that?  

As far as track density, and not being able to move the helix, a helix is a big chunk of real estate and unless you're working with a huge basement, you're not going to have a lot of options as to where to put it. If my plan left an unused spot big enough for a 5' helix and room to walk around it, I would rework it. That wouldn't be very efficient use of the limited space that I have, in my opinion.  

Randy