# S-Curves



## Bluestem Lady (Jan 6, 2008)

Hello, 

I am in the process of building my layout and have a question about laying track for a s-curve. I'm using two 10' dia. curve pieces and would like to know if you it is best to put a straight piece of track between the two pieces? I will also be laying two other s-curves using 12' dia. curves. If it is essential to have a straight piece, what would be the minimum length? At this point I just have two LGB starter trains, but hope to have a layout that will accommodate most trains people would bring to run. It would be a whole lot easier to make adjustments now than later! /DesktopModules/NTForums/themes/mls/emoticons/whistling.gif Thanks. 

Cindy


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## toddalin (Jan 4, 2008)

You can run a 10' diameter S-curve without problem for most equipment. I run my heavyweights though a back-to-back 8' diameter S-curve without problem (typically). 
However, it would be better to put a straight section between. While any straight piece will help, a 3' piece of straight will render a very nice looking S-curve with fewer problems. 

Do not use a turnout as your straight section unless you put at leat a 6" straight piece piece next to it along the turnout's diverging straight section. Otherwise, as the engine goes through the turn-out then curves away from the turnout, the "talgo" (truck-mounted coupler) will push the heavyweight's talgo toward the curved path resulting in a continual source of derailments! 

After trying other fixes for this problem, I eventually had to go back and add the 6" piece of straight beyond the turnout and this totally cured it.


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## Dr G (Jan 16, 2008)

Cindy, 

Todd is right, you can get away with an s curve if it is large enough, and your rolling stock is small enough (such as LGB starter equipment). A general rule of thumb in track planning is that the straigt section should be at a minimum the length of the longest piece of rolling stock you plan to use, this prevents the end of one car from moving laterally in the opposite direction from the next car. This is what causes derailments. One note on the switch in the straight section--if the diverging route curves the same direction as the curve at the point end of the turnout it will work well. A train comming into or out of the diverging route will just continue in the same curved direction, not reversing the direction of travel. I hope that makes sence. 

Matt


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## Bluestem Lady (Jan 6, 2008)

Thank you Todd and Matt. I appreciate your answers and yes, they make perfect sense to me. I did not plan on using any turnouts in the s-curves, so I'm okay on that point. I'll make the adjustment and add more length in the straight piece of track. Sorry I hadn't replied sooner, my satellite connection has been non-existent most of today. Thanks again. Cindy


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## Dr G (Jan 16, 2008)

No satellite connection? Must be Fay's fault./DesktopModules/NTForums/themes/mls/emoticons/tongue.gif 

Have fun with the new layout, and don't forget to post pictures. 

Matt


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## Greg Elmassian (Jan 3, 2008)

If you run body mounts, you really want the straight section to be the length of your 2 longest cars. Otherwise the cars can still be at a sharp angle when halfway through the S curve. 

Regards, Greg


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## Guest (Aug 24, 2008)

with LGB starter trains even R1(four foot dia) s-curves work ... tecnically. 
it just does not look very nice, when the coaches or wagons change direction so apruptly. 
for one foot long rolling stock even half a foot of straight track between the curves help a lot. 
with your planned 10' dia curves a one foot dia straight section between curves should be enough even for wagons of a foot and a half length.


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## vsmith (Jan 2, 2008)

Cindy, it depends, S curves are funny things 

One thing you havent mentioned is which couplers are you planning on using long term and you mention "visiting trains", well theres the rub, what may work for your trains may derail something a friend brings. If your planning on sticking with the ubiquitous standard LGB hook and loops then you can run pretty much thru anything, but if a vistor has body mounted knuckle couplers they could bind and derail at the S section. On my layout I run very short stock w/ link and pin couplers on the smallest curves R1, and even then found that I needed a striaght transitional section (only 6") to prevent the cars binding and derailing on the two S curves I have. 

I would still suggest planning ahead by _at the least_ using a 12" straight section between the S curves sections, this at least minimizes the possibility of visiting trains suffering from a potential negative effects of the S curves. 

Good luck and dont forget to post progress pics


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## Dave F (Jan 2, 2008)

As stated above, much depends on the radii of the curves. I have two S curves on my layout. One is comprised of two 5' raidus (10' dia) pieces of track... no problems. things run just fine. The other is comprised of two 2.5' radius (5' dia), it's no end of headaches. I'll be fixing that issue in the next week or so (read that as getting rid of the S) .


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## Dean Whipple (Jan 2, 2008)

The general rule when using body mounted couplers is that you should have at least a straight section of track equal to the longest piece of rolling stock you plan on running between the 2 curves.....


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## Bluestem Lady (Jan 6, 2008)

Hello! 

I really appreciate everyone taking time to answer my question. When I built my raised bed, I mis- marked on my layout where my hubby pulled the electric through. I was marking the layout for contouring and realized I was off five feet and I had tracks going right through where the line came up. That is what brought up the 10' diameter s-curve. I had already planned on the two s-curves using 12' dia. track. I redid my layout on paper and can allow 36" straight track on all the s-curves. I think I will proceed with that when I can finally start laying track. I have finished building my tunnel and now trying to build the mountain, stream and pond. I will post pictures when I finish that part, but it will be a couple of weeks since we are leaving on vacation next week. 

Cindy 
Bluestem and Doga Creek Railroad


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## vsmith (Jan 2, 2008)

If you can fit a 36" straight inbetween the s curves, then you shouldn't have any problems at all, good luck with it.


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## cmjdisanto (Jan 6, 2008)

In my opinion, sometimes, those pesky "S's" are un avoidable but also offer a sort of character to things. Maybe most look at them as Taboo, yet there are examples of them in real life as well. Like I said just unavoidable. 
In our new layout we have a couple. Nothing that uses track smaller than 10 and usually/always a straight of some sort thrown in between. 
The pics I provided show the example of our "S" curves. You'll see Martha's Narrow Gauge Euro stuff running on them without issue. I have more modern SD-45's and longer rolling stock in the form of modern tankers from USAT. I can honestly say that I have no issues getting a MU with consist through the layout. Yeah if I don't keep up on maintenance and just run trains with-out checking things I have issues but that can be said for any layout, with or without "S" curves. 
































So to echo what a couple have mentioned already......you should have no problems.


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## CliffyJ (Apr 29, 2009)

I was wondering about s-curves myself, and just read this post -- so glad I did, very instructive! I'm now reworking my plans for inserting 2' straights. 

Question: wqhat about yards, i.e., close-proximity parallel sidings? I'm planning on 8" track separation, and my switches of choice (Train Li R3's, 3'-11" radius) don't allow for much of a straight there. Is there an exception to the "rule" in this situation, that is, chance of fewer derailments with slower speeds? 

Cliff


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## BodsRailRoad (Jul 26, 2008)

Posted By CliffyJ on 07 Sep 2010 03:35 PM 
I was wondering about s-curves myself, and just read this post -- so glad I did, very instructive! I'm now reworking my plans for inserting 2' straights. 

Question: wqhat about yards, i.e., close-proximity parallel sidings? I'm planning on 8" track separation, and my switches of choice (Train Li R3's, 3'-11" radius) don't allow for much of a straight there. Is there an exception to the "rule" in this situation, that is, chance of fewer derailments with slower speeds? 

Cliff 

I use 4 Train-Li R3's back to back on each end to make up my 3 track rail yard. 
The inner and outer most rail any equipment can run through with no issue, (USA Aluminum Streamliners 38" long go through with no problems). The center rail can only be use by trains with normal rolling stock, meening boxcars, coal cars ect. If I try to run my USA aluminum streamliners through the ends off the cars actually hit and knock each other off the track.


I also have S curves and once I added the 40" straights between the transitions everything was smooth, without it my long cars would force each other off the tracks at the transition points. 

Ron
 Uploaded with ImageShack.us


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## George Schreyer (Jan 16, 2009)

I run 8' diameter track and have several places with S-curves, sometimes turnouts are part of the curves. I knew from the start that body mounts would not work well in these conditions so I stuck with truck mounted Kadee couplers. 

I also have some S curves at R1 on the indoor layout, but it has all smaller equipment, a 40' boxcar is about as big as anything gets. I use truck mounted LGB couplers there and I haven't detected any S curve related derailment problems. Some of the shorter 4 wheel cars (Aristo and Bachmann cabooses) as well as the shorter 4 wheel locos, have body mounted couplers and they work too, but only because they are so short.


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## Greg Elmassian (Jan 3, 2008)

What's not to like about S curves? (s curve by 2 back to back Aristo WR switches in crossover, just out of sight on the right.











Seriously, there are yard designs that minimize S curves...


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## caferacer (Jul 22, 2010)

Thanks I was going to ask the same questions with my 10 foot curves with a 4 foot straight between them and 14 foot curves that run back to back which should be ok hopefully caferacer


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## Totalwrecker (Feb 26, 2009)

Prototypical Railroading!










While I'm at it I think I found a pic of you with your first loco!










Have a great day.

John


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## Greg Elmassian (Jan 3, 2008)

Yep, sure looks like Santa Fe FT A unit #107, although the nose looks really flat in the picture! 

Greg


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## aceinspp (Jan 2, 2008)

Yep that's them European train folks. Try to run two tracks at once. Later RJD


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