I have a plan!
I've been through a great many potential plans as I've tried to decide if I really want to take the time to build a significant layout in this basement. Because of the shape of the room, the majority of them were large ovals with steady grades that allowed it to loop under itself and continue to staging under the main layout. I was trying to avoid the complexity of a helix since I have a double-track mainline, plus an extra single-tracked branchline. I'd like all staging from all three directions.
Recently, it occurred to me that if I move a door, then I'll have a small side room available as well. More space is a good thing, but the placement isn't great. But it did open the possibility of placing some staging there.
The other factor is that all of the plans would require a duck-under (more likely a crawl-under) or a section that could be opened since there would be multiple levels of track.
The current layout is a literal dogbone. It's a double-track main, and the line loops back onl itself, so the right track becomes the left track. This arrangement basically allows one 20' wall for modeling, along with the two 10' walls.
With the extra space from the side room, though, I can push one or both of those loops outside of the room and still have decent aisle space. The problem once again, though becomes staging.
Then the obvious struck me. Instead of a loop, build a helix at each end.
The helixes would be simple spirals, no turnouts and go down to a lower level of staging. It would also complete a loop of the entire layout if I want to have continuous running. Since the Hartford trains go through to Waterbury, each train will have it's own dedicated staging track, it would just return to the one it left from , but from the opposite direction. This reduces the number of staging tracks in half when compared to a point-to-point arrangement. Better still, the aisle will be a continous S-shaped aisle - no duck-unders. This is especially important since the basement also happens to be where I need to store my guitar amp, and I wasn't looking forward to duckunders, etc. with a 50 lb amp.
The Berlin staging will only need a small stub-ended staging, really only two tracks. There is only one train scheduled during a given session from this direction (and will head toward Waterbury, so it needs a track in the main staging as well).
The other great thing this will do is extend the Hartford side of the Highland line, leading to the station. There were a number of industries here, and also the long siding where the through freights drop off cars. So this will extend the mainline run nicely and will focus attention on the Highland Line.
Other than potentially limiting the length of trains, the helixes won't affect the operation of the layout at all. The trains will only use the helixes the enter and exit the layout. I could even use serial staging in the helix for the inbound trains, since it's a double track main.
Another nice feature of this design is that the staging and main decks will be level. It makes the construction much easier, with the exception of building the helixes. I'd like to use the masonite spline construction for the helix, but the thickness of the spline might be two tall for helixes with a small radius.
And ironically, there may still be a good amount of space in the middle of the room with this design, so it may allow some use of the basement for other activities.
I'll be taking some measurements when I get home today, and Bill will be over to check it out in about a week as well so I'll be able to see what he thinks. But I think I have a winner.