I often hear 18" bandied about (with 22" given as a better alternative), but is this the true limit? Or just for modern (or semi-modern) mainline operations? I'm a big fan of the Small Layout Scrapbook website, and given that I live in a none-too large apartment, and that all my power/rolling stock is mid-70s 4 axle stuff (Geeps, etc.), I was kicking around alternatives to a simple 2 x 6' Inglenook, and attempting something... uh... riskier.
One concept I was considering was the 'Wood End' point-to-point design, possibly constructed on a 30" width hollow core wood door. Here are some (grainy) photos of the real thing to give you an idea of what I am talking about:
Now, obviously, that isn't HO (I don't think it's N, either, but the British use a lot of intermediate scales that North American modelers don't generally touch), and it's pretty clearly designed for 2-axle steam-era rolling stock.
However, the question here is not so much if something could be done and look good, but simply if it could be done at all. So is 18" the smallest true radius for NA stuff, or can you go smaller but restrict what you run?
Shrike Arghast ...So is 18" the smallest true radius for NA stuff, or can you go smaller but restrict what you run?
...So is 18" the smallest true radius for NA stuff, or can you go smaller but restrict what you run?
In a word, yes, although I don't really know what you mean by "...true radius..." Eighteen inches is the de-facto minimum radius for all but the tiniest of rolling stock and locomotives with two close-set trucks or only two driver axles if steam. For the most part it is a function of the engineering of the scale models provided to us, or made by us, but there are always outliers. Some ore cars, some trams, some interurbans, and the docksiders are examples of the latter.
Everything is a compromise for those of us modelling or playing with mainline rolling stock. If you want to do a subway, a rapid transit system that runs on an elevated roadbed (Sky Train in Vancouver, BC), or a small mining/logging operation, you can always get down to whatever practical limits those items have. It might even be as low as 10".
Shrike ArghastOne concept I was considering was the 'Wood End' point-to-point design, possibly constructed on a 30" width hollow core wood door.
I believe that Wood End is an OO9 layout, what we in the US call HOn30.
I think that this is clearly stated on the Carl Arendt web page where you may have found the photos -- scroll down about halfway.
HOn30 is narrow gauge HO models on essentially N scale track and mechanisms. For this reason, HOn30 can typically go around much tighter curves than standard gauge HO.
Some HO standard gauge layouts have been built at 15" minimum radius and even tighter, but even modest cars and locos may need some modifications to work reliably. Since radius is measured to the center of the curve, a 30" wide hollow-core-door won't be adequate for a 15" radius turnback curve, although a 36"-wide one would -- barely.
Good luck with your layout.
Byron
Layout Design GalleryLayout Design Special Interest Group
This will be a ratio, not a number.
Lower limit = 2.5 x length of average car. Recommended minimum =3x length of average car. 'Comfortable' radius = 4x length of average car.
Looking at an HO forty foot box car, approximately six inches long, this gives a lower limit 15 inch radius, a recommended minimum of 18 inches and a comfortable radius of 24 inches. For sixty foot cars, increase by 50 percent. For Minnesota ore cars and short locomotives, decrease proportionally.
In my own modeling, I have one railroad, allegedly located by following a mountain goat up the high end of the Tomikawa Valley, which has 350mm (sub -14 inch) radius curves (and stretches of 4% grade) operated with very short or very flexible cars and locomotives.
Flexible? The Mantua 2-6-6-2T, that now resembles a JNR E10 on steroids, can handle a 12 inch radius thanks to blind drivers and really short rigid wheelbase. I also run a four truck machinery flat which actually has the wheel geometry of a pair of very short cars connected by a bridge.
So, how about the JNR route that sees longer cars, longer locomotives and higher speeds? 610 mm (24 inch) radii with long spiral easements and generous side clearances. Most of that rolling stock is embargoed from the short line - and has no reason to ever go there.
Chuck (Modeling Central Japan in September, 1964)
Hello I was in the process of building a 30inch by 80inch HO scale layout be we had to move I used 15 inch radius curves #4 switches all code 100. I used the Bachmann GP7 for power which had no problem with the curves and did not look bad. I used Athearn and Atlas 50' boxcars with no problems plus 40 foot cars. Some of the older Ribbon Rails 50' boxcar derailed.
Hello all,
To throw the proverbial "spanner in the works"...With the American, HO standard gauge, 15-inch radius the minimum available in sectional track.
On John Allen's famous Gorre & Dapheted he hand-laid curves equivalent to 12-inch radius in some sections.
You can manipulate flex track to tighter curves than that.
Many people purport that 18-inch sectional track is the "minimum" allowable radius.
On my pike in incorporate both 15-inch curves and #2 Turnouts.
The largest motive power I run are 4-axle GP's, RS-units and F-units along with various switchers, all with no problems.
My longest consist is 4 MU'd GP40's and they have no problems negotiating the #4 & #2 turnouts.
The maximum car length on my pike is limited to 56-feet or articulated depressed-center flat cars.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
When i got started, 15" radius was regarded as the smallest commercial track radius (I have some recollection that Flesichmann had 14" radius, or am I thinking of Maerklin?). Of course back then the most popular locomotive was Varney's Dockside B&O 0-4-0T which could probably take 10" radius, depending on what it was coupled to. Also back then, the popular flex track was Atlas's fiber tie/brass rail which was difficult to bend to a radius tighter than 18 inches.
Dave Nelson
dknelson When i got started, 15" radius was regarded as the smallest commercial track radius (I have some recollection that Flesichmann had 14" radius, or am I thinking of Maerklin?).
When i got started, 15" radius was regarded as the smallest commercial track radius (I have some recollection that Flesichmann had 14" radius, or am I thinking of Maerklin?).
Roco actually makes 358 mm Radius track which converts to 14 3/32" inches in code 83. (I have two 15 degree sections on a sanding tower track.)
I'm still undecided on the matter. I have the space (barely) in our basement for a 4x8, but that is a rather large commitment. The last time I built a railroad that size was over 15 years ago and in N-Scale, and I found it totally unmovable when the time came.
However, in the intervening decade and a half, I've definitely honed my craft - swapping out heavy benchwork and plaster for plywood (or no) base and foam-only scenery. I do believe that, using these methods, I could actually make a 4x8' portable... the question is whether or not to commit. I know a lot of people view such railroads as small fy but, to me, it seems like a huge undertaking.
Shrike Arghast......but, to me, it seems like a huge undertaking.
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
Your era makes a difference too.
For example I found that while 53 foot well cars will go over 18" curves for a modern pike they overhang terribly (in fact even on 22" curves.). Hence the SIW is limited to 40' well cars.
(This was the inputus for my earlier thread about shortening well cars).
If your era is older and not completely freelanced like mine 40 or shorter cars that can handle tighter curves might be appropriate.
Joe Staten Island West
Shrike ArghastI'm still undecided on the matter. I have the space (barely) in our basement for a 4x8, but that is a rather large commitment. The last time I built a railroad that size was over 15 years ago and in N-Scale, and I found it totally unmovable when the time came.
How about building the 4x8 in 3 sections? Make two sections 2x6 and arrange them back to back on opposite sides of a double sided backdrop. Then connect them with a 2x4 section that has a 180-degree curve of about 20" radius.
Make the two 2x6 sections reusable and the 2x4 disposable. If you move into a more generous space, you won't build a new layout with tight curves so just have the tight curve on a small disposable section of the layout and put all your serious effort into the 2x6 sections.
You could also reduce the impact on your current space by cutting off the corners of the 2x4. Or, if you want to save more space, you could make this section a drop-leaf.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
For the record, my Bachmann Spectrum Ten Wheeler (3 axles and double lead truck) and my Spectrum Shay run fine over 15 inch radius curves. 15" is a necessity on my 4X8 if I'm to run multiple trains!
Shrike Arghast I'm still undecided on the matter. I have the space (barely) in our basement for a 4x8, but that is a rather large commitment. The last time I built a railroad that size was over 15 years ago and in N-Scale, and I found it totally unmovable when the time came. However, in the intervening decade and a half, I've definitely honed my craft - swapping out heavy benchwork and plaster for plywood (or no) base and foam-only scenery. I do believe that, using these methods, I could actually make a 4x8' portable... the question is whether or not to commit. I know a lot of people view such railroads as small fy but, to me, it seems like a huge undertaking.
As was mentioned above, a 30" door will not allow for 15" curves in ho. a 36" door and the use of flex track would allow you to get up to 16 or 16.5 inch curves with a bit of space left over, A 17" radius would put the track at the edge of the door, something you probably don't want to do.
You can bend flex track as tight as you like. Running a train on it is another matter. A little goat engine, and 20' cars can do it and even look good. LION has 15" curves (not by design) on the layout of him (they were supposed to be 26" go figure) but this is not an issue with 50' subway cars.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Your first sentence pretty much says it all. Yes, 15" radius has been used successfully, and there was even a time when 15" sectional track was offered commercially. Operation on 15" radius with anything larger than an 0-4-0t and a few ore cars was an iffy proposition. Eighteen inch radius usually requires small equipment and care in track laying to be sure the curve is smooth and consistent. Twenty two inch radius is more forgiving. In general, six axle diesels and most passenger cars will look and operate better on larger radius.
Mostly, it depends on your equipment, your operating scheme, the precision with which you lay your track, and the visual impact of trains operating on those tight curves. However, you do what you can in your available space.
Tom
ACYthere was even a time when 15" sectional track was offered commercially.
That time is today.
Atlas, Bachmann, Hornby, and Kato all still sell sectional track of 15" (or less) radius.
I'm not endorsing it's use, just noting that it's still available.
I have found that 15" will work with 40' and shorter cars behind the Bachmann 4-4-0. Years ago, I had some 12" radius track that could handle my MDC boxcab diesel and 36' cars. Accurail says they are releasing some 36' cars this summer.
For really tight curves, you can use talgo trucks (couplers mounted on the trucks vs the carbody) from Kadee.
Good luck
Paul
BroadwayLion You can bend flex track as tight as you like. Running a train on it is another matter. A little goat engine, and 20' cars can do it and even look good. LION has 15" curves (not by design) on the layout of him (they were supposed to be 26" go figure) but this is not an issue with 50' subway cars. ROAR
Lion:
Subways are a different animal (Pun Intented)from other railroads in that one would see curves do to the lack of availiable space for easements so I would think that 15" curves would be okay.