A basic question from a newbie re radiuses.. (Radii??)


Skip

Skip

New Member
Just got permission from the boss lady to use a basement room for my new HO layout.
(This is really neat because she's already given up part of our dining room upstairs for a small 027 oval layout!) :D It's an odd shaped basement room as it's under the upstairs bay window so it bows out on one side. Basically it's 11 feet long, and one end is 6+1/4 ft wide while the other end is 9+3/4 ft wide.

As continuous running is important to me (I'm really a toy train guy at heart?) ;) I'm thinking of setting up a snaky around the wall dog bone layout with a reversing loop at each end of the wider sides of the room. Construction won't be complicated, just one level of cut plywood using a bookshelf and some storage cabinets underneath as supports.

My (beginners!) problem is: I'm not really sure how much space (board width) the HO radius's require, so I don't know if my simple plan will fit in the room? Can someone tell me the minimum widths of flat plywood sections I would need to contain an 18", a 22" and a 24" radius reverse loop? -It would be really neat if I could get a double track reverse loop on each wider side of this room!

Much thanks for any suggestions and assistance here,
Skip
 
Just remember that, for a looped design variant, including the dog bone type, you really need to think of the diameter of a 180 degree curve, not just the curve radius. This is because your curve eventually must turn back on itself to take your trains to the other end of the layout, even if the route is sinuous. So, for your really-very-tight HO radius of 18", you need 36" to complete the turnback curve. However, the general consensus is that it is safest to have at least two more inches of layout surface outboard of the curve, all along it, in order to "plant" a retentive hedgerow or fence of some kind, something that will catch a derailed locomotive or item of rolling stock and save it from an expensive and losing altercation with the surface next down.

So, now we're at about 40". You can safely turn back a train on a curve of 18" radius if you have 40" in which to lay the curve AND have some room to spare to catch a tumbling locomotive or car. Note that, the tighter the curve the more overhang some parts of the locomotive will have outboard of the outer rail. So it's good for that reason to have some room to spare outside the curve. That's reason #2.

As you broaden curves to the extent possible without compromising the safety of your rolling stock or your overall layout design, you decrease the likelihood of problems with couplers staying tight on the curves, with tracking, and you'll get less overhang and odd looking trains that could only exist and run on our cramped layouts. You'll also open up your layout to future issues of both locomotives and longer cars, such as 85' passenger cars if your curves are upwards of 26". Some very appealing brass locomotives have 30" radius minimums, as an example.

Plan for a reliable layout today, but think a bit about possible future acquisitions that will also run well without imposing modifications on you.
 
Where is the entry to this room, because that will influence/decide what areas you have for return loops.
 
My first suggestion would be to forget sectional track and consider flex track. The broader the curves the better off you'll be. Trains look so much better on broad curves. You won't be stuck with a fixed radius. Like mentioned in the previous post, you could consider a duck under or possibly a drop down section. I have a three track hidden staging track that allows for continuous running. My layout was built mainly for switching and is primarily a point to point layout, but when the grand kids come over, the drop down section is set into position and around the trains go.
 
The formula I use to determine the space I need is:

Edit: I forgot to add that radius is the measurement to the center of the track.

You will need to add 2" to get the outside dimension.

(radius + 2" x 2) + clearance.

Example: ((24 + 2") x2 )+ 2 = 52 + 2 = 54" for a 24" radius. minimum.
Double the clearance if both edges are the edge of the layout.
 
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Depends on what locomotives and rolling stock you will be running. Big steam, long passenger cars, I'd err toward the long side: 24-32+" radii, If you're going to be running short switchers and 40' cars: 22-24" radii, if you're using switchers only, slow speed operations and just have to because of space concerns: 18-20" radii. Anything less than 18" on HO is asking for trouble. IMHO.
 
Thank for all the replies so far. Some answers:

Yes, I did consider a duck under, but at 77 with bad knees and a tricky back I don't feature ducking under even the almost 4 ft high platform I'm planning! ;>( And I'd rather not use a drop down (or lift up) section as I want to keep things somewhat plain and simple...

The doorway to this room is not a problem at all as the room's 11 ft measurement I gave ends at a closet, and next to that is the entrance way door in an alcove so it doesn't even figure into taking up space. (I would remove the closet door however as it opens into the room.)

And I was really pleased by some of the answers... Because I figure if I have 116" wide space at the bigger end of the room then I think I could use as much as two 48" wide platforms for the reversing dog bone loops at each wall side? I figure this would still leave me a 20" width for an entrance way into the larger middle of the room (and the smaller end) where the trains would hug the wall. So at 48" (trimmed to the actual curves) that should probably leave me enough room for a double track reverse loop of two tracks with a 22" and 25" radius, with 3" space left between the tracks?

(-And I would really appreciate someone checking my figuring here? ;>})

As far as the philosophy of planning for bigger trains later goes I don't feel the need to think that way at all... All the locomotives I have now, GP9's, F2 and F7's, SW switchers and a few small Connie and Mike steamers, I made sure they were rated for 18" radius operation before I bought them. And if I do feel the need to run a Big Boy type later then I always have my MRR club? Also I don't mind passenger cars looking unrealistic on tight curves as I'm also a tinplate guy; have you ever seen 6" Marx lithographed tin cars zipping around 027 curves behind a smoothed down blunt looking Commodore Vanderbilt? Realism? -Are you kidding? .... ;>})

But anyway thanks again to all for the assistance! -And please let me know if my concept of 48" wide panels for double tracked 22" and 25" inch radius reverse loops is feasible?
Skip
 
48" wide will not work with 25"radii. 22" will be fine. Go as large as possible as stated earlier. You may have small engines now but every model railroader sooner or later starts to drool over a big boy or an sd40 or dd40 etc.
can you sketch up a drawing of your room with dimensions. We can help guide you more in the right direction and explore more possibilities of a functional layout and functional room.
Steve
 
choops said:
48" wide will not work with 25"radii. 22" will be fine. Go as large as possible as stated earlier. You may have small engines now but every model railroader sooner or later starts to drool over a big boy or an sd40 or dd40 etc.
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No, I can guarantee I will not do this! I've been involved with various aspects of mrr'ing for a long time, mostly with Lionel as a kid and now with Marx 027 tinplate and some HO. Any further HO ambitions now are just to have something big enough (and lightly scenery'ed enough) to run some moderately sized trains round and round and to have an interesting operating and test/program track layout to DCC-program MU consists of my smaller engines for running at my mrr club. For example I did own some larger Lionel "O" scale steamers recently but sold them so I could go with the much lighter and smaller (and less expensive?) Marx 027, which is basically 3-rail "S" or 3/16th scale. At my club I see guys alla time with giant steam articulated boomers and cab forwards and UP diesel Verandas (both in O and HO), and they do not float my boat at all! (I suspect my club buddies think I'm a bit 'weird', what with all my Marx and RMT shorty engines?) So generally with mrr'ing and locomotives my credo is mostly 'less is more...' :)
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can you sketch up a drawing of your room with dimensions. We can help guide you more in the right direction and explore more possibilities of a functional layout and functional room.
Steve
Click to expand...
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I will attempt to do a drawing, although it will not be true to scale...
Meanwhile the replies I've received here have already been very helpful and encouraging, and what I'm now planning on doing is to set up my two 48" wide plywood panels at the end of my dog bone, placing edge fences on the sides not against a wall, and then running an outside radius loop of flex track as close to the fence as possible. Then I'll just move in 3" to lay another parallel track loop, and what runs on it, does! (And what doesn't, goes on the o/s run!) :rolleyes:
Thanks All,
Skip
 
A drop down bridge may be what you want. I was a bit younger when I started my layout. 68 now and I did find out that I don't seem to bend as easy as I used to. The average bench level is around 48 inches and the drop down bridge was a simple solution. A piece of plywood, a piano hinge and a couple of latches to hold it in place when it is up. If you're interested, I'll take a couple of pictures and post them. My layout room is fairly large but by using the drop down bridge I managed to keep my minimum radius to 32 inches. I do run a few passenger trains and they look so much better running on a broad radius as do long trains.
 
Skip,
Is this the room shape, or does it does it go the other way? These dimensions are from your first post.
Skip1_zpszjnlnopc.png


Its 11' long, 9-3/4'at widest, and 6-1/4 at narrowest. Where's the closet door and entrance door.

Or am I just barking up the wrong tree here,(woof, woof).
 
Cjcrescent said:
Skip,
Is this the room shape, or does it does it go the other way? These dimensions are from your first post.
Skip1_zpszjnlnopc.png


Its 11' long, 9-3/4'at widest, and 6-1/4 at narrowest. Where's the closet door and entrance door.

Or am I just barking up the wrong tree here,(woof, woof).
Click to expand...

Thanks for taking the time to do this! The closet would be flush within the white stuff at the left, and the entrance door would be in the bottom white area beneath it. I'll have to draw a sketch tho because one of the walls is not flat but bulges out (under an upstairs bay window), and this wall is 9+3/4 feet only at the widest part of the bulge. it's hard to explain. I'll try to draw something. But you do have the basic measurements w/o the odd stuff included....
Thanks,
Skip
 
My_HO Room floor plan.jpg

Okay, here's the floor plan for my HO room. As you can see it's irregular in size. The scale I used is 1/2" equals 1'.
It's not an exact precise scale, but fairly close...
Thanks,
Skip
 
Looks like a decent space Skip. If you were to have a removable or drop down bridge at the door, you could easily have a continuous run around the room twice with broader radius curves at least twice around the room. Trying to have a "folded dog bone" type of layout would eat up real estate in a heartbeat.
 
I drew up your room in autocad and tried to layout a folded dog bone. There is really not enough room to do it. I agree with Montanan that a shelf layout around the perimeter is your best solution.
Steve
 
choops said:
c840f4315912f6b3101cabcb7c76169e.jpg
Click to expand...

That's a great looking plan! Looks like there's even room for a small storage yard in a central area there. Only things I might like to add to it would be perhaps some sidings for passing and for a station or two. Also I'd connect my parallel main lines with a crossover...

Okay, since you guys are obviously more knowledgeable than me in this you're starting to convince me about going with an around the room drop-down shelf layout. Only thing is I'm not a tool master (not too bad but no expert?) and constructing a drop down shelf I can easily use and still have trains run flawlessly over it scares me some?
-But I'm willing to bet next someone here will post me some good instructions and descriptions about this?:D -This is a great asset, this forum! -Thanks guys!
Skip
 
I'll try to take some pictures of my Polish engineering drop bridge for you when I get home if you're interested.
 
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