The Southern Railway Memphis division circa 1975

[Specter3]

Either reverse the door(open out) or barn door sliders.

[Specter3]

Getting close enough to start working on deck heights. Rigged up these stands and built some modular benchwork to figure out what my deck heights will be. Prior plans used a partial nolix which drove the deck heights. This plan is purely reliant on the helix for travel between decks. So deck heights are up for personal preference. Separation has been suggested to be in the 16 inch range. Here is 60 and 44. I am 6’1” and in looking at it it “looked” good. But once I tried to reach into the top deck it felt really awkward. This made me remember a video I saw on the tube that suggested top deck height be max the height of your armpit. Otherwise you have to elevate your elbow higher than your shoulder to reach in. It said, and after some actual actual experience I believe it, that doing so is uncomfortable and will eventually be painful. So I will be dropping the deck heights some.
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The layout will be built in “modular” sections. We don’t intend to move again(lived in our first house, which is 5 miles away for 20 years) but in the event of who knows what that would force a move, the layout can be taken apart in sections.

So dropping the top deck to 56 inches based on armpit height looks like this:
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Dropping the lower deck to maintain 16 inches looks like this:
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Then placing what will be the staging level(which will only be the on opposite side of room. At 28 inches looks like this.
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Which gives plenty of reach in clearance and makes the staging level and lower level chair accessible. Will rolling chairs be regularly used? IDK, just figuring this stuff out. But I am sure during construction they will be. Floor will be luxury vinyl plank as it is waterproof(remember basement) easy to put in and, so far in rest of basement, very durable. Places of long term standing can have standing pads like in the grocery stores for the checkers.

[GaryHinshaw]

Looking good.  Given the style of your plan, with a fair amount of switching on the upper deck, I would probably go with the 40/56" choice, which seems to be what you're leaning towards.   I would avoid the smaller deck 12" deck separation - the lower deck will seem dark and cramped once the upper deck is covered.

My upper deck ranges from ~57" - 67", but it is mostly mainline running (at close to eye level - I'm 6'-0"), which I've been very happy with.  I use step stools to access the one switching area there: a cement plant at ~65".  But since you have a lot of switching areas around your plan, a bunch of stools would be less practical, so the lower height is probably better.

For staging, a 12" separation is probably fine, unless you expect to be doing a lot of train re-staging there, which often means dealing with cars that won't couple or uncouple properly in places where you can't see them very well.   But if you're just going to be turning trains around without much switching, it should be fine.

One other thing to consider for a multi-deck plan: think about how much infrastructure work needs to be done underneath each deck.  This might dictate the order in which you build things, so that you keep construction access relatively easy.  You'd be surprised how often you want to drill a pilot hole for something, only to realize that, once you're farther along, you can't get a drill in there...

[MDW]

Following up on Gary’s comments......
Now is a good time to  figure out how you are going to light the lower decks.  It the lights are going to sit below the benchwork modules, that will effect the actual clear space you have between decks and it’s better to plan for that now.

I used 60”/ 42” as base heights and assumed 3.5” minimum for benchwork and LED tape light + another .5” to cover the tape light.  That Results in 14” clearance, which feels right for me.

Looking forward to watching your progress.
Michel

[Specter3]

Basic wall colors up. There will be a lighting valence over the top deck. The meeting point of the colors will be covered by benchwork. Base of the helix started. It will be open in the center for the capability of crawling up inside it for Maintenence. With crawling being the operative word.

[MDW]

Looks like you are off to a good start - congratulations!
Michel

[Specter3]

Thanks Michel!

Helix base up on temp legs at 28 inches. [ Guests cannot view attachments ]

[GaryHinshaw]

Great progress!

Now try crawling into the helix opening to make sure that you can.  (And imagine doing so 10 years from now.)  You might decide you want to raise every level by 4" or so.

[Steveruger45]

Yes, great  progress.   FYI, I find one of those mechanics creapers from harbor freight quite useful for sliding in under the layout as well as for changing the oil and filters on the cars.

[MDW]

Great progress!

Now try crawling into the helix opening to make sure that you can.  (And imagine doing so 10 years from now.)  You might decide you want to raise every level by 4" or so.

Yep.  This post had me running to the basement for a test climb into my helix!  I’m safe with about 42” clearance off the floor, but not sure how I’d do at 24”...... it’s worth a check before you go to far down this road.
I’m sure you’ll figure it out.

Michel

[Specter3]

Funny you guys should bring that up. In my former life I ran an aircraft cleaning company(think auto detailer and Lear jets) I still have one of my ultra cush creepers left over from that and I had already had the thought. As I set it up and looked at it at the first time I did consider that it was low and crawling under would be a task later in life. But to keep the upper deck at a reachable level it could be raised maybe 4 inches. Any more and you are talking lots of step stools for building and operating if you keep deck spacing at 16. So you could lose an inch or two of the staging deck(at exit of helix, it could decend a bit before the actual yard maybe?)and an inch or two between and raise it an inch. That is definitely something to think about. As many people that do the stool thing I am hesitant to practically mandate it from the start. But it is something to consider. I last built a helix when I was in high school for an HO layout I had in my parents basement. It worked reliably as long as speed was kept low. But alas, no pictures have been found of that layout. Suffice to say it was structurally scary having been entirely constructed of spruce furring strips. Yes you read that correctly. Level? plumb? Never heard of em! But it did run and before it was torn down after my second year in college, the upper deck did get scenery. That was one track and grade be damned. This will be three from the bottom level going up and grade should stay below 2 based on calculations. The outside measurement of the helix is 50 inches so that should allow for a 24in, 22.5, and 21in radius tracks.

I built some modular benchwork pieces with ripped plywood as the material. Around the walls I am going to use lag screws to attach the 12in wide decks to the wall. I believe that will be enough to support them. The one wall with 18in deck will have angled supports on the bottom(no staging under this deck in current plans, but as I think about it it could change). And the upper deck will have some metal L brackets for that section. Or larger lagg screws with a load spreading metal plate.

On the peninsula is where my next engineering thoughts are needed. The current plan has staging occupying the entire bottom of the peninsula. Support for the middle deck can be on the outside of the staging deck if needed. But between the mid and upper deck my first thought was to run all the way to the ceiling with strong enough members to cantilever the 24 in wide area from the center(12in to either side, like the pic below) but the plan has a decidedly different use of space between the two decks. The mid deck has the space unevenly shared to one side and the upper deck has it skewed the other way. It is 24 inches across plus the vertical support in the middle. The mid deck uses 18 inch on the right side and 6 inch on left. The upper deck uses 6 inch on the right and 18 on the left. Gotta think about it.

[MDW]

Interesting challenge.....
If you can create enough strength, rigidity, & stability through the staging and lower decks, then you should have the freedom to shift the upper deck off center.

I had a similar problem with a single, mountain ravine scene sitting on top of a typical 2 sided lower deck peninsula.  Used a tall plywood girder through the center of the peninsula to save depth - my basement is just 9’ wide so every inch counts -  but a traditional 2x stub wall that ends at the upper deck would probably work better if you can spare the extra few inches.

I’m sure you’ll sort this out.
Michel

[Specter3]

Large update. Went to my mothers for 10 days to help her with some things. Fixed a rotten place in the roof. This was caused by a seriously crappy flashing and underlayment job. I have gotten to the point where I believe roofing companies do just enough to make it last about 7-10 years betting that the current homeowner will have moved by then and it will be the next owners problem. Flashing is not rocket science. There are all kinds of books and online resources. Please use them.

Back to the layout. I continue to build modular benchwork sections. Since the floor has yet to be put down all benchwork is simply tacked up.
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The biggest thing I needed to firm up was  the design of how I was going to support the upper deck on the freestanding section. Based on this work I believe I can build it the way I have in the pictures. The staging level will be supported on the outside with legs that run just inside the benchwork sections. These will continue up and support the lower scenic level as well. I layed out the track plan 1 to 1 using printer paper and figured out where the backdrops would be.
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Where the backdrop is I ran 2x4s vertically up to where the level of the top deck is. The reason this is such an issue is that the scenes on the two decks are not the same depth above and below each other. The lower deck is 8 inches on the south side and about 20 inches on the north side. The top deck is the reverse. The backdrop on the top deck will be thinner and have supports that run into the ceiling that will attach to the rafters in multiple places. 
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The neat thing that I am discovering as I roll out the plans in 1 to 1 on paper is that it is not as cramped as it feels on the plan page. In multiple places I have been able to spread some things out as they have taken up less space in full size than I thought they would on paper. Now that is unusual for this hobby.

Next big complexity question. I can make the IC interchange at Haleyville live. I have plenty of space to do a single track helix down to the lower deck and would dedicate a track or two in staging for the IC freights in either direction. Since the IC had trackage rights from Haleyville into Birmingham to model it would be a pretty big step up in complexity and capability. But the run would be very short on the actual layout. It could have reversing loop with a couple of tracks on the level to allow a couple of IC trains to be used. Both options would require a decent amount of hidden trackage. But a cheap spy cam and Chinese tablet would help that. Something to think about. 

[MDW]

Nice structural solution to offsetting the deck centers.   The upper deck seems stable enough?
Michel

[Specter3]

Without being attached to the wall and only having one run up to the ceiling it is very stable. Once it is tied to the wall and has the full set of vertical supports it will be solid.