Removable roll away bridge between layout sections... Maybe a Double Helix..

[learmoia]

Suppose you were to limit the layout to one or the other room.

I'll pretend you didn't say that...

But I've never been a fan of double deck layouts..

~Ian

[Point353]

I'll pretend you didn't say that...

But I've never been a fan of double deck layouts..

~Ian

That certainly helps narrow down the possibilities.

Would a double drawbridge, pivoted at both ends and joining in the middle, provide a wide enough opening?

[peteski]

Would that make it modeling a fast clock in real time..?

No, even slower than real-time. Snail-clock. 

[learmoia]

Since the double helix would risk tearing the fabric of space time..

No, even slower than real-time. Snail-clock. 

We're back to the bridge idea.
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Suppose you were to limit the layout to one or the other room, but make it a double-decker, with one relatively shorter helix connecting the two levels. Would that give you a sufficiently large layout and/or long enough run?

I'm not a fan of double deck layouts..... but.......
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This is something to think about.. and that would free up the other side of the basement for the wife's rock supplies.

Measuring out the difference in main line run.. I only loose about 150" (12') of main line run between the two designs.. which is the distance of the bridge..

A couple of other layout design pet peeves I'm trying to design around..
-No Duck Unders but reliable swing/draw bridges would be OK
-No points where the train leaves your view and reenters at another point in the layout where you have to walk around the layout to get to it.-
-Minimum Radius 24"
-Minimum Isle width 36".. Ideally wider..

~Ian

[nkalanaga]

If it's a single level bridge, with both "abutments" solidly mounted to concrete walls, then the span will be absolutely fixed.  In that case, I'd make the bridge from a dimensionally stable material, such as aluminum channel or angle, and mount it with pins at both ends, NOT fastened down.  Put electrical switches under both ends to disconnect the power if the bridge isn't fully seated. 

That way, for normal access, the bridge can be lifted off and set aside, with no tools or special skills needed.  In an emergency, the entire bridge can be knocked up and away with one hand, while barely slowing the person going through.  It would likely be damaged when it hits the floor, but under the circumstances, that would be a minor consideration.

[Ed Kapuscinski]

What about building two separate layouts?

One on your main theme, another on a second, for when you get bored with the first.

[nickelplate759]

Probably a wacky idea, but how about modeling a car ferry?   Load it up on one room, sail (probably really on wheels) to the other.

[Point353]

I'm not a fan of double deck layouts..... but.......
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This is something to think about.. and that would free up the other side of the basement for the wife's rock supplies.

Measuring out the difference in main line run.. I only loose about 150" (12') of main line run between the two designs.. which is the distance of the bridge..

The one-room plan looks promising.
The ability to afford your wife her own space is not a trivial advantage of that configuration.

Do you expect to eventually host sessions with multiple operators?
If so, are those 3' wide aisles going to be wide enough for two people to squeeze by each other?

[nkalanaga]

George:  I did that, in our old house, because there was no room in my bedroom for a helix, and I wanted two levels.  Carry the barge from one level to the other.  What made it odd was that I model the Montana Rockies...

Justification?  An earthquake caused a slide, blocking the river, and the resulting lake flooded the mainline.  So, use a barge to cross the lake.  Not out the question in parts of Montana, as Quake Lake shows.

[Lemosteam]

What if the bridge were an accordion in the plan view with fold down legs every other panel:

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[Cajonpassfan]

In my humble opinion, you have an opportunity to build a very nice and respectably sized single deck layout at optimal elevations, tailored to your height, without the need for double decks, a mid-line helix (or two ) or any other artificial ops joy killing nonsense. The only thing keeping you from accomplishing that (well other than actually building the thing ) is the dreaded "gap".

I'd try to keep it simple, and wonder whether one could span the opening with a single "bridge" piece supported by a strong, stable material such as aluminum channel, set it on fixed receiving keyed abutment nubs. To remove, simply lift from its ops position at say 55" and place on similar nubs at say 7'? I'm thinking a short piece of U-shaped channel at each wall, wide enough to receive the "bridge" would work fine. One person, if tall enough, or standing on a low step stool, should be able to perform this in a matter of a few seconds, or two could do it if there were limitations... The challenge would be finding a channel light enough while strong enough to not flex excessively over a span of almost 10'. Or, I'm sure there are other ways without resorting to helices...
Have fun, Otto K.

[nkalanaga]

Otto:  Basically the same as my idea, but you simplified it to a single piece.  Aluminum channel should work.  I know they make 1x2 inch channel, which would be fine for single track, as well as deep enough that derailed trains couldn't fall off.  Supporting only itself and an N scale train it shouldn't sag over that distance.  It wouldn't look like much, but maybe glue plate girders to the side to simulate a series of through girder bridges?

[Cajonpassfan]

..... It wouldn't look like much, but maybe glue plate girders to the side to simulate a series of through girder bridges?

.... Or if desired, one could use the channel simply for structural support, and glue on top of it 6" wide slab of 2" foam for scenery base? Should be light enough without becoming too cumbersome.
I've seen spans like this masquarading as bridges across doorways or isles, hanging in the air, and it never looks right to me, unless it's a large single span structure and this span it just too wide for that.
I do love the idea and simplicity of powering the removable section by gravity; that's brilliant!
Otto K.

[nkalanaga]

If you wanted a "large single span bridge", built on a single piece of aluminum, take a look at the BNSF (BN) Latah Creek Bridge in Spokane.  A few stub piers mounted on the bottom and you have it.  It would be an excellent place for photography, and the fact that the piers didn't reach anything wouldn't show in the pictures.  That bridge actually is a continuous box girder, in a Y shape, and curved girders, no less.  It violates practically every "rule" of modeling a railroad bridge.  On a more ordinary layout it could be modeled with spline roadbed simply by painting the roadbed, and adding a ballasted deck.

[Cajonpassfan]

Nice shot. Spokane has more amazing bridges per capita than any other place I know of... 
Otto K.