Chimer

I've allowed for the station being on the level, the brown, pink and green bits are flat .....

To illustrate using the simplest example - a folded eight single line where brown track is on the level at the lowest point, suitable for a station, rising both ways to the bridge in the top left corner. Here the gradient is 0.9% (just better than 1 in 100) on the outer loop and 1.3% (1 in 75ish) on the inner to give an elevation of 3" at the bridge. To arrange things so both gradients flatten out to cross the doorway at the same elevation (making a lift out arrangement as easy as possible) should be do-able, but would obviously make the grades steeper. Edit to add - with a 2'6" wide "bridge" across the doorway, both tracks at an elevation of 1.64" (!), and the track coming off the bridge behind the station staying at 3" until the curve, the worst gradient is 1.4% ....

Is that not just caused by you using Streamline geometry (2" centres") for the main lines and R3 & R4 curves (2.625" difference) for the helix?

I've just twigged that we were here about a year ago, with the main differences being that the terminus now exists and a helix has come into the equation - one of the issues then and now is getting trains that leave the terminus home again. How about a double junction on the left-hand side, branching tracks falling inside the main circuit at the top edge of the bottom baseboard to a balloon loop in the bottom right-hand corner? You could take dead-end storage sidings off the loop if really necessary, but you've got a lot of MU siding space already - how much do you need? Any train starting from low-level storage sidings would still need to reverse to get back there, so if these were your main line fast trains you would have to bring them into the terminus platforms, or stop in the through platform 2 and reverse from there ..... I've used 22.5" (R4) and 24.5" radius on the "big bends" to maintain 2" (Streamline) spacing as you're using Streamline points. The gradients are steep, but I guess OK for MUs.

Missed that, sorry ...

It would help with the big picture to know what you're thinking of doing at the bottom of the helix. Just a series of dead-end sidings, or storage loops with a balloon reversing loop at the far end? Or what? Either way, with just one helix, whether single or double track, trains are going to go down from one circuit (the outer clockwise circuit as per your latest drawing) and come back and shift to the other one going the other way round. There is then no way back to the storage sidings without reversing in the visible section, which is an interesting manoeuvre (described by Harlequin above) for loco-hauled passenger trains, and next to impossible for freights with a brake van. And as DCB points out, it works better if a train leaving your terminus can get to the storage sidings without a visible reverse, which isn't possible as presently drawn. As it's a given that the terminus isn't changing, moving the helix to the bottom right corner, with the junction leading to it situated somewhere top-leftish, would perhaps be better (though I can see the temptation to keep part of the helix in that bottom left recess). If there was some way of making the "to be developed" station a junction, such that a train from the terminus could branch off there to get to the helix, this could be operationally very interesting. I can't see any way to make that work, starting from your current "givens". But I'll keep watching and thinking .....

Which means it's the power clip, not the controller, surely?

That means descending trains going anti-clockwise in a British "keep left" scenario, so the entry and exit to the top right helix would have to be switched, which in turn would mean a tight right turn in the visible section on leaving the station. Given the 28"/30" radii used for the helix, hopefully conforming to "standard practice" might not be as necessary as if using R3 and R4 ........

No - if this is a plan for actually building something, you just need to see what happens when you actually put the track pieces together - there may be enough wriggle room for the gap to be unnoticeable. So just leave it for now. But if you need it to be "perfect" without gaps for a simulation, try this - which works in XTrackCad, so might in Anyrail. Close the circled gap by moving the crossing and the SL-100 to its right to their right, so the gap now appears between the crossing and the SL-89 to its left. XTC will not do a "join two tracks" across the gap (it sees the tracks as parallel but misaligned), but if you start a bit of flexi from one side of the gap and make it the right length, it will let you "connect" it on the other side (although in close up you can still see the misalignment). This won't work across the circled gap, as the misalignment there is too great for the "forced connect" to cope with. Best of luck ....

I got this far, noting the OP was inspired by helices, here using 28" and 30" radii and needing access manholes ...... Junction station needs a lot of work, branch terminus on the end of the green line rising from the junction, storage loops inside radius 30".

Those circles look about 5 foot in diameter to me ...

Additional semi-random additional thoughts (before Robin notices and tells me off 🙂) - a double-track dogbone would need a second helix, otherwise everything would end up on the same (outer) circuit with no way back. And with a helix at A and another at C, you could do away with helix junctions and have a visible double track main line joining the tops, and the storage loops/fiddle yard joining the bottoms. Which would leave lots of room for a decent junction station on the AB wall to spring the branch from.

Without leaping into a detailed design, your runaround mainline could perhaps be a mid-level dogbone with the loops in corners A and C. A branch could lead to a (higher level??) terminus along CD, and another branch to a helix in corner A. From the bottom of the helix, you could run at low level to another dogbone loop at C, with storage loops along the wall BC. The mainline dogbone could be single track (which would look double where visible), or double track throughout (which would give much more visible running but might cramp things up too much). The junctions to terminus and helix might possibly be incorporated into a mainline station, but open junctions "out in the country" would be much simpler, if you were prepared to do without a mainline station. The only duck-unders would be to get to emergency manholes in the centres of the loops in corners A and C. And having written that, I've re-read your OP and realised that conforms pretty well to your para starting "One idea I had" except that I'm only thinking of one helix, which would serve as an out and back to the storage loops. Any good?

Wouldn't dream of calling it bizarre! Here's one I did for myself some moons ago which uses the same basic peninsula idea but without the bother of handling reverse polarity ...... it's an end-to-end from one side of the fY to the other. Some people (e.g. Phil) have probably seen it before ..... Apologies ITG for the hijack! The station is at high level, the Fy low, and the linking gradients are the tracks round the edges (behind backscenes). And I do have clear access from above the top edge.

Not too difficult, and I quite like the staggering of the platforms ..... I've edited yesterday's post with this version as well .....

I know I over-complicated things (as well as making the mistake!), but I was trying to make the station look like two double track main lines coming together and diverging again. So I doubled the reversing section to try to maintain the illusion ....

First statement correct - oops! Second statement - we'll have to see!!

As promised .... mostly for my own enjoyment ... Here you have a low-level double track roundy-roundy dogbone (brown) with a double junction top right leading via a gradient (green) to a high-level terminus (add own design from point marked T). A 1.8% grade will get you high enough to clear the low-level tracks by the intersection point near T, you could carry on climbing for a while to increase the vertical separation between terminus and the storage loops, which can be added as desired between points A and B. Return to terminus is achieved by using the purple tracks through the station area which act as reversing loops. Using DC you would stop a train in the platform and switch over so power comes from the other end, driving on in the same direction with the controller reversed. With DCC, I believe you would use an auto-reverse module, but I've never investigated how that works or how to wire it. I have used 22" and 24" radius to from the ends of the dogbone. In practice I would probably use R3 set-track curves with little fiddles to increase the clearance as necessary to avoid conflicts, but these take ages to draw accurately ..... Cheers, Chris

If you feed in the tracks from a terminus to a double track roundy-roundy (dumbbell or oval), you either need to set up your storage roads so trains can reverse there and change tracks (which in an era featuring steam engines and brake vans almost always involves lifting and turning stock by hand) or contrive a reversing loop. For an oval setup, a reversing loop usually involves a line cutting the operating well in half. For a dogbone, I think I can see a tidier way of doing it but don't know whether what I'm thinking of can fit. Will have a play later for the sheer joy of it ....... Meanwhile, the single track out and back pretending to be a double track presents no reversing problems - unless you are going to fret about the first class section of the train being next to the engine on both outward and return journeys ..... Cheers, Chris

Have to admit my original design didn't have any goods facilities in it at all, though a goods yard could be fitted in bottom left instead of loco stabling. Whatever .... This pic has my flying/burrowing junction replaced by a conventional double junction using a diamond - the track shown in pale blue is there purely to make things look like a standard double track main line with a double track branch, anything circulating on the low level continuous run would stay on the brown tracks. I'm assuming the scenic area stops at the vertical line to the left of where the blue line ends. I've also brought the storage roads forward and pushed the terminus approach back as you prefer it that way. The bridge over the visible storage roads would be tricky to make look good!

I'm not sure you've gained anything by doubling the top right loop (OK, you can go round it in either direction, but so what?) , and because tracks cross in the top right corner you've halved the length available to gain the necessary separation between the levels. My design was mimicking double track throughout - I'll draw it again over the weekend with a conventional double junction instead of the flying one, to try to show what I'm getting at.

Yep, I reckoned with mine a helix probably wasn't necessary. But if one did go in, it would need to be bigger than the 3rd/4th radius shown. 360 degrees @ 24" radius about 150", so a 3" gain would be a 2% grade. And the tighter the bend, the greater the drag.

You're right about it being a single track out and back, but with an extra loop (brown dumbbell top right) to provide a continuous run on the lower level (for running-in etc, or just to have something running while you shunt the terminus). So the green gradient comes down into the middle of the dumbbell on the bottom level. The line that goes nowhere (which you've correctly identified) is just there to give the impression of a double flying junction in the middle of this area which might be modelled as open country, where there would otherwise just be the single point which would look a bit strange. Besides, I've always liked the look of flying junctions ..... Edit to say by "flying junction" (or "burrowing junction") I mean a double-track junction where one of the branching line tracks crosses under or over the main line on a bridge, instead of on the level using a diamond crossing. Which takes up a huge amount of space ......

Yes. I can't (now) see any reason not to put the terminus approach on a viaduct behind the storage yards and bring the yard forward a bit. Would help with emergency access bottom right too. Whether I'll remember a reason for doing what I did when I try to change it around, who knows?

I think this is not too dissimilar to Phil's thinking ...... not fully developed, obviously. Brown - dumbbell with storage loops on lower level Blue - terminus (one I made earlier) at higher level. Probably with loco stabling in the bottom left corner rather than the goods yard I had in the original. Green incline joining the two (something around 20 feet total length, so 4'5" (ish) at 2% grade. Dotted green - helix if required for greater separation. The brown line that goes nowhere is hinting at a flying double junction, though the point that actually leads to the lower level dumbbell is the one immediately after the storage yard throat. You would need a couple of emergency access manholes bottom left and top right (and maybe top left). Big enough to get a head and one arm through! Third radius minimum. Food for thought? Cheers, Chris