I know about twice arounds really well truth be told it was the first layout ive ever had, but my next door neighbor built it and sold it to my parents when i was about six. Anyway’s i was looking in to building one “i know i have been through so many plans its rediculous” but i really like this design and would like to stick with it. My question is on a 5x9 foot space maybe 10 if i can talk my dad into it what would be my curve limitations i want my minimum radius to be 22’'. Also would it be possible to climb over one track instead of having a grade crossing? Any help would be greatly appreciated!
I think I made one on top of some SOFT Cover books…
smaller layouts than 5x9 have done twice around over N under. Yeppers. 22 inch radius is fine you can go 24" if desired. 3 percent grade is about 1 inch in 3 feet, that would actually be 3 inches up in 100 inches, I use the 3 ft to 1 inch as a close guess, so in 9 feet you can have a decent grade and get high enough for an over N under.
If you feel that your preferred track plan doesn’t really allow you to get the barest minimum clearance over another part, where one passes overhead of another, you can split the difference. Have the bottom track go into a dip and then rise out the other side of the overpass. Lots of guys do that, still getting the clearance they need, but each grade on the top and bottom is now about half of what it would have had to be. You can even get your trains longer as a result.
Does that help?
I have a twice around, what we call a folded loop, and it gave me twice as much visible railfanning trackage as my first layout as a result. I learned, applied the learning, and am the better and happier for it. If twice around/folded loop is important, then try the over and under rises and dips.
Now thats what i wanted to hear 24’’ radius curves with the big engines i have i dont want to put too much stress on them with tight curves and steep grades!
SD60M–
My Yuba River Sub is a rather extended 24x24’ ‘twice around’ disguised as non-parallel double trackage. Actually an extended folded ‘Dogbone’. I have two areas where the track crosses itself, both of the upper tracks being on a 2% gradient, while the lower track stays level for a time. The clearance is sufficient for my rolling stock (1940’s, so no double-stacks here, LOL!). But no matter what your layout size, ‘twice around’ offers a lot of running space, and if you plan it right, a lot of operational possibilities.
Tom [:)]
Here is a big question is it possible to double track it in such a small space? I say this because i want to run more than one train even though im about to switch to dcc and do plan on having a small yard and engine terminal.
Probably not without going to 15"-18" curves. (6’x10’, maybe) You could put cross overs or bypass tracks in that would allow you to run it as a twice around or two separate loops.
Selector-That’s a good idea about making half the grade below table level. I never thought about that.
My first N scale layout was a variation on this Atlas plan:
This plan had very sharp curves and 3% grades, both of which significantly reduced my enjoyment of the layout. It now sits stripped bare in my garage, pending an upcoming yard sale.
You get twice as long a run in the same space with a twice around (obviously), but you pay for it with grades and possibly with sharp curves. Also, while it’s neat at first (as the train comes round the mountain, each time it’s on a different track), you realize having the train pass through the same scene twice but at different levels isn’t all that realistic.
Oh, I know, there are a whole host of situations where that happens in real life (like on the Clinchfield a few hours west of me), but the point is, it’s not common enough to look natural.
My current layout has less track in the same space, and just looks more realistic. Plus, I opened up the curves and I have no grades. Thus, longer trains and larger steam engines can now ply my rails.
Consider that the maximum radius you could use would be the same as if you had a simple double track oval. Essentially, that is what a twice around is with the tracks crossing over on one side of the oval. You have 60 inches of width. You’ll want a minimum of 2 inches (3 would be better) between the track and the edge of the layout on both sides so the width of your outter oval is 56 inches maximum giving you a maximum radius of 28 inches on the outside. You could probably get by with a 26 inch radius on the inner loop although 25 1/2 might be safer depending on the length of equipment you are running.
Now a double track twice around is going to look like a 4 track main on the non crossing side. With a clearance of 2 1/2 inches between tracks, the inner most of the four loops would have maximum radius of 20 1/2 inches.
All this assumes your loops are parallel with the layout edge which can be boring scenicly. If you wanted to angle the loops slightly so the mains rain slightly diagonally to the layout edge, you would have to reduce your radii accordingly.
My concern with a double track twice around is that a lot of your layout space will be eaten up by mainline track. This doesn’t allow much for yards, industrial spurs, or non railroad scenery.
Ok im going to stick to single track. That will hopefully give the room for a small yard, industial spurs, and everything else. So if i use 24’’ curves for the outside oval and 22’’ curves for the inner oval i should be ok? My largest loco’s and cars are SD70MAC’s and double stack well cars would this present a problem down the road with the curves. Should i go with 26’’ curves?
In 5x9 that should be very easy.
Would it be ok to run intermodal equipment with 24" and 22" radius curves and 3% grades? Also would any of my big engines have problems on a curved grade like this my biggest loco’s are SD70MAC’s and Dash9’s. Im started to get really excited and i hope i can get all the details right before i rush into this and screw up something!
Before you commit to 22" and 24" radii, you might want to check that your longest equipment can negotiate those curves without sideswiping a train on the parallel track. It has been a long time since I built a layout with curves that sharp and I’m not positive 2" between track centers is sufficient on the curves. It seems to me I’ve read somewhere that 2.5" or even 3" is a safer spacing.
My last layout was a twice around, it was set up so that trains could run on just the outside loop, or go thru a pair of no.6 turnouts and a 12-1/2 degree grade crossing to go around both the inside and outside loops. The outside was basically an oval, but the inside one was more of a peanut shape, giving the layout a little less of a symetrical look. (Also the inside loop was elevated about an inch compared to the outside loop.)
I had a reverse track going from one side of the inner loop to the other, to allow trains to reverse direction; I also had a small yard inside the inner loop, using part of the inner loop of the twice around as a yard lead. That way, I could switch cars in the yard while a train ran on the outside loop without them interfering with each other.
Total layout size was 6’ at the ends narrowing to 5’ in the middle, and 16’ long in HO.
My first Bear Creek and South Jackson was a twice around in 4x8 (but not on a flat sheet of plywood! Lots of vertical). Here’s a link 4x8 BC&SJ
It had 18" minimum radius in it’s 4x8 space so in a 5x9 the plan could be expanded to a 22" radius (but it wasn’t designed with snap track in mind). It had two (scratch built) diamonds but neither were on the main line. The track was ME code 83 flex and turnouts were the old-style Walthers/Shinohara #5s (#6s would have taken too much space). There was a single town,one run around track, and a short branchline. No place to turn a engine (wye or turntable) and a very rudimentary engine track in the town. It was the first layout I’d finished to any real degree of completion. I went a bit overboard with the plaster rock castings - 120+ of 'em on a 4x8 layout (using homemade molds). One thing it did have was a LOT of different vignettes as you’ll see if you follow the link and look at the various pictures.
Here’s one of my favorite scenes…
Regards,
Charlie Comstock
My layout is basically a twice around, but only if I set the turnouts to route the trains that way. This is also a temporary arrangement until I can get more of the layout built. As you can see below, I’m currently sharing the space with my son until I get another bedroom in the house renovated.
The areas that are grey haven’t been built, and the red lines indicate the temporary trackage. The twice around is located on the main body of the layout in the lower left side of the image.
It’s really pretty basic, a folded oval intertwined with a figure 8. The overall dimension of the L is about 12’ x 6’, with the long end being 3’ deep and the short end 4’. The track that circles the room by way of the yard connects the main body of the layout with the staging yard hidden underneath.
I’m hoping that sometime in the near future I’ll be able to put up the rest of the benchwork and build my “real” yards. The scenery on what’s now the peninsula will be replaced with more and bigger mountains, and will be served by the Chaffee Branch. You can see the greyed out section is part of Cumberland.
I currently can set the switches to run several trains in the same direction over a continuous route (DCC makes this possible with less headaches) or run one in each direction simultaneously (Impossible without DCC) using the passing sidings for running meets. When the layout is done, the Thomas Sub (the figure 8) will be broken and run as a point to point from Maryland Jct. to Elkins, which will be located over my son’s bed…
Here’s the “Final System Plan”…
Hopefully I’ll make it that point… Then it’s on to the next room!!