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Classic Atlas HO Layouts with 15-Inch-Radius Sections

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Classic Atlas HO Layouts with 15-Inch-Radius Sections
Posted by Shock Control on Friday, January 12, 2018 11:36 AM

Several of the classic Atlas HO layouts, as included in books such as "Blueprints for Atlas Snap-Track HO Layouts," will incorporate one or two small sections of 15" radius track.  I don't think I've ever even seen 15" track, let alone used any.  

I'm curious how trains perform on these layouts.  Are the sections so brief that they do not hinder the operations?  Is it easy to modify the layouts to avoid the 15"" sections?  (I realize you may need a larger space with this option.)

Thanks!

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Posted by tstage on Friday, January 12, 2018 11:48 AM

I haven't seen R15" curves in a while but it does exist.  The minimum radii for most HO locomotives is either R18" or R22".  Some smaller steam and diesel switchers though could handle curves as low as R15".

IIRC, the majority of layouts in those Atlas track plan books would be considered "spaghetti bowls"; trying to cram as much track as possible in a certain footprint.  I always try to go as large a radii as possible and keep the track plan simple.  It looks more realistic that way.

Tom

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Posted by Atlantic and Hibernia on Friday, January 12, 2018 12:06 PM

I have used 15" radius track in places and with my very small locomotives there was never any problem.

Kevin

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Posted by Doughless on Friday, January 12, 2018 12:14 PM

At the time the plans were published, Atlas sold 15 inch radius sectional track.  I don't know if they still do.

Long cars will not roll well if coupled in long cuts.  I would keep by loco choices to 4 axle diesels and steamers with no more than six drivers.  A 0-8-0 or 2-8-0 might work depending upon the manufacturer.

A couple of sections would generally still cause problems, although not as much stringlining of long cars as would an enitre 15 inch radius loop.

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Posted by 7j43k on Friday, January 12, 2018 12:23 PM

Atlantic and Hibernia

I have used 15" radius track in places and with my very small locomotives there was never any problem.

Kevin

 

 

In my first layout, I used Atlas 15" radius curves on an industrial siding.  Only 40' cars and switchers went there.  It worked fine.

As a bit of further information, a real UP SW10 could take a 15" equivalent curve, without train.  An early Baldwin could best that, at 7" equivalent.  And 16 1/2 WITH train.

 

Ed

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Posted by Lone Wolf and Santa Fe on Friday, January 12, 2018 12:38 PM

It doesn’t matter how short the section of track is, if it is tighter than the minimum radius for a locomotive it will cause a derailment.
You definitely need to alter the track plan to 18 inch curves but it would depend on the actual track plan to say if it would be easy. Even 18 inch curves are too tight for longer cars and locomotives but 4 axle diesels and cars 60 feet and under should be fine.

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Posted by rrinker on Friday, January 12, 2018 1:17 PM

 Smaller equipment will have no problem. At the time of those plans though, many HO cars had talgo trucks with the couplers mounted ont he trucks, not the car body. This enabled them to at least be pulled through some very charp curves. In the early days of HO, 18" was the luxury radius, 15" was fairly normal and common. And the most popular locos were the Mantua 0-4-0 camelback, or the Varney 0-4-0T "Little Joe" Docksider. Either of those could easily negotiate an even smaller than 15" radius curve. Remember, at the tiem there was also Lionel, negitating 27" DIAMETER curves - 13.5" radius - an that was more or less O scale! 

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Posted by Bubbytrains on Friday, January 12, 2018 2:02 PM

I have built a couple of Atlas layouts which specified 15" radius curves. The best one was the famous Morgan Valley RR. The 15" curves were on spurs, not the mainline, so it worked fine with slow switching using an Atlas Alco S4, and 40' cars. 50' cars did not work. Later I modified the layout design to use 18" curves because I wanted to use 50' boxcars for an industry. The other Atlas layout I built was the double-loop "up and over" using a riser set and girder bridges. The plan uses 2 15" curves on two spurs. Right from the start I knew I wanted 18" curves, so I had to modify the plan by shifting the bridge pier locations.

 In summary, yes Atlas 15" curves are still sold, and yes they do work, but you have to accept using diesel switcher locos and 40' or shorter cars at slow speeds.

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Posted by wjstix on Friday, January 12, 2018 2:59 PM

According to the Walthers website, Atlas and Bachmann (EZ Track) still make 15"R HO track sections. Kato makes track with 16-7/8" radius; I believe one of the European HO manufacturers makes 14"R track.

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Posted by IRONROOSTER on Friday, January 12, 2018 3:35 PM

I have operated the Bachmann 4-4-0 with 5 cars (40 ft or less, body mounted couplers) around an oval with Atlas 15" radius curves with no problem.

This was a test setup to see how the 4-4-0 worked, so I didn't try larger locomotives. 

Paul

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Posted by Shock Control on Friday, January 12, 2018 4:16 PM

Thanks all for the replies.  I am considering doing the Up and Over in 4' x 6', but on a 5' x 7' table to allow for more scenery along the perimeter.  It sounds like I can modify the 15" sections on the spurs, and I may move the one that goes under the bridge to another location.

I run all mid-century trains, so I'm sure they will have no trouble around the 18" radius.

By the way, Atlas sells all of these older layouts as packages, with a code 83 or code 100 option.   

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Posted by dknelson on Friday, January 12, 2018 5:12 PM

I was surprised to see that Atlas is still selling 15" radius snap track (in fact it is currently on sale at Walthers).  And I sure remember when you'd see plenty of layouts, even some ambitious ones, that had at least some 15" radius track - in an era which emphasized appropriate rolling stock such as an SW switcher or F7, 40' freight cars, shorty passenger cars with talgo type trucks, and so on.  

Speaking of appropriate rolling stock, some of the big AHM/Rivarossi articulateds were recommended were advertised as being able to run on 18" radius, and more than a few guys learned that they could even handle Atlas 15" radius curves.  And in the article "The Mostest Track in the Leastest Space" in the January 1965 MR, Eugene Platt wrote how his big brass Akane 2-8-8-4, rated at 20" radius, took his 18" radius curves with ease.  One photo in the article shows at least 16 brass locomotives of various sizes, but some quite large, on his 4x6 layout.  It has to be seen to be believed.

Dave Nelson

 

 

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Posted by rrinker on Friday, January 12, 2018 7:10 PM

If you expand it to 5x7, you'll have reach issues to the middle, but also you can probably repalce all the 18" radius with 22" and the 15" with 18". And still add some extra straights to make it wider.

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Posted by Shock Control on Friday, January 12, 2018 8:10 PM

rrinker

If you expand it to 5x7, you'll have reach issues to the middle, but also you can probably repalce all the 18" radius with 22" and the 15" with 18". And still add some extra straights to make it wider.

                                    --Randy

I will be able to walk around the table. I want to keep the track the same size so I can fit more scenery.

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Posted by BRAKIE on Friday, January 12, 2018 8:50 PM

Shock Control
I run all mid-century trains, so I'm sure they will have no trouble around the 18" radius.

You should have no problems with engines and cars from that era. Just remember nothing longer then a 2-8-0 or 4-6-0 or no diesel longer then a 6 axle SD7/9  or Alco RSD 4/5. These engines look at home on 18" curves.

Larry

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Posted by SeeYou190 on Friday, January 12, 2018 9:46 PM

wjstix
Kato makes track with 16-7/8" radius;

.

Kato actually offers HO scale UniTrack all the way down to 14 9/16" radius!

.

-Kevin

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Posted by Shock Control on Saturday, January 13, 2018 9:43 AM

BRAKIE

 

 
Shock Control
I run all mid-century trains, so I'm sure they will have no trouble around the 18" radius.

 

You should have no problems with engines and cars from that era. Just remember nothing longer then a 2-8-0 or 4-6-0 or no diesel longer then a 6 axle SD7/9  or Alco RSD 4/5. These engines look at home on 18" curves.

Yes, I have mostly F3s and F7s.  The only steams I have are 0-4-0 shifters. Mostly 40' cars with a few 50' thrown in for variety. 

The only troublesome car is a crane and boom tender, but I will probably just park that one on a siding. 

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Posted by jjdamnit on Saturday, January 13, 2018 6:18 PM

Hello all,

Yes, 15-inch radius sectional track is still available- -in code 100 and 83 from Atlas. Be it on back order status from their website.

On my pike I have asymmetrical curves of sectional track. Two are 18- to 22-inch while the others are 15- to 18-inch curves.

I could have used flex track but for the expedience of time; read I'm lazy, I went with sectional track.

With these tight curves I only run four-axle or smaller diesels and 0-6-0 or 0-4-0 steamers.

I also have sidings and a Wye made up of PECO #2 turnouts. All the GP's have no problem negotiating these. 

The coal drags are 12 to 24 cars long of vintage Tyco 34-foot operating hoppers, upgraded with body mounted couplers and new trucks. 

A 4 unit set of GP40's with 24 of these cars negotiate the loading siding made up of #2 PECOs.

The center piece of my layout is a spiral trestle made up entirely of 15-inch sectional track.

One modification that has been discussed on other posts is using longer shank couplers on locomotives to negotiate the smaller curves and/or turnouts.

With few exceptions I use Kadee medium-shank center-set couplers with no problems. The exceptions are due to conversion constraints.

One M.O.W. 60' flat car uses the same couplers as the rest of the rolling stock with no problems negotiating the cross-over made with Atlas Snap Switches.

I tried an SD locomotive. It worked but looked awkward on the tighter curves.

Hope this helps.

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Posted by wojosa31 on Saturday, January 13, 2018 6:42 PM

Yes, 15" radius curves are still sold. back in the 1960s when I started out, they were quite commonly used, by people with space limitations, and Interurban Modelers. Back then, 24" radius was considered a broad curve.

FWIW, there were numerous tight radius industrial sidings on the prototype railroads at the same time. Very little freight equiment exceeded 50' in length.

Today, most of these obsolete sidings are gone, along with the 40' cars that used them, however, if one was modeling Urban Industrial Lines in the 1960s or earlier, 15" radius curved sections and 18" radius "Snap switches" are quite useful, in certain applications. Just don't expect your favorite SD70 to run over them.

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Posted by WVWoodman on Sunday, January 14, 2018 2:48 PM

I have a return circle which has about 4 different 1/2 sections of 15 in radius spaced out between 18 inch radius full pieces.  My Bachmann Spectrum 2-8-0's have not had any problems in that area.  

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Posted by SeeYou190 on Sunday, January 14, 2018 7:10 PM

jjdamnit
Two are 18- to 22-inch while the others are 15- to 18-inch curves. I could have used flex track but for the expedience of time; read I'm lazy, I went with sectional track.

.

I prefer to use sectional track for curves of 18, 22, or 24 inch radius. I use flex track for larger curves.

.

Using sectional curved sections assures me that the curves are smooth with no kinks. I find this much easier.

.

-Kevin

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Posted by jjdamnit on Sunday, January 14, 2018 7:47 PM

Hello all,

SeeYou190
Using sectional curved sections assures me that the curves are smooth with no kinks. I find this much easier.

To clarify; I used three sections of each radii to form a full quarter-round then added a 2-inch section of straight track for a transition from one radii to the next.

Knowing full well that the beginning point of one side of the asymmetrical curve will be unequal at the other end, with no kinks in the track. 

I also built trammels- -in the different radii- -then noted when the tangent points of the differing curves met and added those small pieces of transitional straight sections.

That's how I decided that a 2-inch section was the "Goldilocks" cure for my situation.

Sorry for the confusion.

Hope this helps.

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Posted by cedarwoodron on Monday, January 15, 2018 7:27 AM

I looked at some of the old Atlas track plans published in the 1960s and it seems that the 4x6 plans used segments of 15 degree curved track to keep the rails in from the edge of the layout or to fit a siding inside an 18 degree curve. The larger plans-4x8 and up, don't use the 15 degree curved sections, although that old classic "Ho Railroad that Grows" by Linn Wescott uses the smaller radius sections to shoehorn in more track on the 4x8 surface. Those of us who relish the old days and have smaller steam and diesel units  as well as shorter rolling stock can still enjoy the flexibility of mixing 15 and 18 degree curved sections. These days, the use of flex track allows for much more variation in curve geometry.

Cedarwoodron

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