Turnout radius in yards, both curved and straight vs minimum radius.

[craigolio1]

Ok let's say my minimum mainline radius will be 18" (less on industrial tracks etc. ) having chosen this minimum radius so that my passenger car fleet will looks it's most awesomest.

Now we come to my yard. No way I'm having turnouts with a 18" radius on their diverging route, so obviously I'm going with smaller turnouts. In my case I spent like $200 US on a Fasttracks #6 turnout building kit so I have a feeling I'll settle on this as the turnout I'll have to make like 50 of for my yard.

I don't anticipate that I'll be running many of my passenger trains through complicated yard ladders but I do have a fleet of Red Caboose center beam cars that are pretty long, so I get concerned when I think about the tight curve that results in #6 turn out. Don't get me started on some of the S curves I may have to design out (I'm using a prototype yard as inspiration and hope to stick as close as possible to its layout).

Is this concidered a problem or can pretty much anything negotiate something like a #6?  The Fasttracks website shows curved turnouts that have radiai as low as 12"/9" (planning to use #6 for those too so I can use the point and frog tools). How small can I go before my three unit lash ups of 6 axle diesels pulling my center beams derails in the curved turnouts that may wind up at the yard entrance?  Do I make that one an 18"/12" or a 20"/14"? 

Maybe someone can offer some insight? I have never laid track before.

I'll try to find a diagram of the yard and post it for interest sake.

Thanks.

Craig

[craigolio1]

OK.  I found a good one:



The design will work like so:

The ferry slip and C yard will be separated from the main A and B yards by a 180 deg curve so that if you are facing the main yard, the ferry slip and C yard will be on the wall directly behind you.  By doing this I can commit one entire unobstructed straight wall of my basement to the A and B yards.  This gives me 19.5 ft of length to use including, from left to right, the curve around to the C yard, ladders at both ends,  and the curve required at the "Stockett" end which will be the exit to the rest of the layout.

The entrance at the "Stockett" end will likely have it's first three turnouts on the curve.  Also the turnouts that run to tracks 2/3 in the A yard, and 3/4 in the B yard might be curved ( as would their reciprocals at the other ens) to make the transition into tracks 3(A) and 4(B) more fluid,.  I don't know I'm just throwing it out there.

Yardmasters, please tell me what you think.

Thanks, Craig

Edit:

I may eliminate the C yard, or make it very small and for interest purpose only.  The A and B yards were for assembly and disassembly.  I can unload the ferry into them.  In its use during my modelling period the C yard wasn't really used and the A & B yards were never full. I'm still not sure about what I'll do there.

[wcfn100]

Now we come to my yard. No way I'm having turnouts with a 18" radius on their diverging route, so obviously I'm going with smaller turnouts.

You lost me here a little bit as the diverging radius on a #6 is bigger than 18".   

I'm also not real clear on why you need curved turnouts.


Jason

[craigolio1]

See , well I didn't know that. Thanks for bringing that to my attention.

I had planned curved turnouts where the entrance to the yard is just to save space at the entrance, so I don't have to leave enough length to avoid s turns created by coming in on a left turn and immediately hanging a right on the lead that goes to the run around track. I figured curved turnouts there would smooth things out.

On the other ones I figured it would make a smoother transition into that last track in the ladder but I guess its not needed?

If a number 6 has a radius of more than 18" then I guess this whole post was pointless! Thanks, that makes it easy.

Craig.

[nkalanaga]

As far as operations go, #6 should be fine.  I run passenger cars and 89 ft flats with body mounted couplers through #6 crossovers with no problems, and mine will go through #5 turnouts easily enough.  For curved turnouts, with your cars, I wouldn't go much below 18 inches, as my passenger trains tend to dislike curves below 17.  That could be because most of the cars have 1025 couplers, and if you use 1015, or truck mounted, you might be able to use tighter curves.

[OldEastRR]

Generally cars (whether freight or passenger) moving through a switch ladder are going slowly, not whipping at high speed like on a mainline curve that is too tight to negotiate. S curves are unavoidable on yard ladders and at scissors crossings at terminal throat trackage. The thing is nobody is racing at high speed through these curves so there's usually no problems.

[mmagliaro]

I have Atlas #7 almost exclusively, and all my long steam and 80' passenger cars go through those with no trouble.
There are a couple of spots in a yard where I used the #5, and that's pushing it, at least for the long steam.  They
can just barely make those curves.

I know you didn't say anything about steam locos.  I'm just pointing out that the difference between #7 and #5 is
huge, even when crawling through a yard.  If you are able, avoid anything tighter than a #6 wherever you plan on
running longer cars and engines.

[craigolio1]

Thanks for the interest guys.

My passenger cars also have body mounted couplers so if I have to use curved turnouts I'll be sure to stick with my minimum radius or higher.  Good advice.

I get that trains move through complicated track work slowly, but for our purposes don't we also need to make sure that there is a straight section in the middle of an S (crossover or whatever)?  No matter what the speed if the two cars are on two different curves they'll pull each other off.  Or are you saying that a #6 provides that tangent between curves?

I've got some preliminary track plans I'm going to post for discussion but I'll do that in my Layout Engineering thread if anyone is interested.

https://www.therailwire.net/forum/index.php?topic=35666.0

Thanks again.

Craig

[craigolio1]

I have Atlas #7 almost exclusively, and all my long steam and 80' passenger cars go through those with no trouble.
There are a couple of spots in a yard where I used the #5, and that's pushing it, at least for the long steam.  They
can just barely make those curves.

I know you didn't say anything about steam locos.  I'm just pointing out that the difference between #7 and #5 is
huge, even when crawling through a yard.  If you are able, avoid anything tighter than a #6 wherever you plan on
running longer cars and engines.

I don't have plans for looooong steam but I will have a CPR Royal Hudson and some point and I have more passenger trains than a normal model railroad should so that is very relevant.  That being said, those trains will be set up and run around (I'm planning #10s for the main line), not switched in the yard.  This yard will be designed for 60ft box cars and 70(?)ft center beams as the longest cars to manage in the ladders.

Craig

[nkalanaga]

Yes, numbered turnouts, such as the #6, are straight through and beyond the frog.  So, on a crossover, you have the curve at the points, then a straight section through the two frogs, then another curve.  For ladders, you still have a shorter straight between the frog and the next points.  I suspect that's part of the reason the prototype does it that way. 

The main reasons are that with straight frogs the same frog can be used for left, right, and wye turnouts, and, back when frogs were made from rail, instead of being cast, it was easier to make them straight.  The prototype almost always chooses the simplest and cheapest solution!

[Rossford Yard]

I have all Atlas C55 No. 7 in my yard (see photos in the Layout Engineering Report under "Indiana Harbor Belt of Texas) and have no problems with 89 foot cars while switching.  On my last layout, had the Peco medium radius in my yard, no real problems.

While I have a few curved turnouts, overall I recommend against. Even since my days in HO, curved turnouts seem to give more problems.  Actually, very little on the Peco, but my Atlas curved turnouts seem to get out of gauge some somehow more than others.

I understand it is very tempting, though, and some spots you just can't get away without them.

BTW, I think the gentle bend in the middle of that yard will look great!

[mmagliaro]

...
While I have a few curved turnouts, overall I recommend against. Even since my days in HO, curved turnouts seem to give more problems.  Actually, very little on the Peco, but my Atlas curved turnouts seem to get out of gauge some somehow more than others.

I understand it is very tempting, though, and some spots you just can't get away without them.

BTW, I think the gentle bend in the middle of that yard will look great!

I have exactly one Atlas code 55 curved turnout in my layout.  It was the most troublesome of all the Atlas turnouts.
I had to do a lot of filing and shimming to get it to be all in gauge all the way through the points and all the
in/out routes, and stay put.  It works well now, but it was a pain.  It suffers from all the woes that the other
Atlas turnouts do: point rail gauge too narrow, point rails uneven thickness, rails that flare in or out on gauge because the
tie spike detail isn't strong enough to hold them securely, and then there's the flimsy drawbar, the wonky point
rail hinges, and the electrical jumper bars underneath that are bad on nearly every turnout I've ever gotten.

But... curved turnouts are awesome for gaining extra space in a yard and opening up trackplan possibilities, so
I wouldn't shy away from them.  I'd just shy away from the Atlas ones.  As you point out, when I used Peco code 80
turnouts, I had a number of curved turnouts and they were rock solid.

[robert3985]

Users of Atlas 55 turnouts should be aware that they are ALL built to non-conforming specs, meaning the distance from the point of the frog to the toes of the closure point rails is much shorter than if they were properly proportioned.

What does this mean????  It means the actual effective diverging radius on an Atlas C55 #7 turnout is approximately the same as on a properly configured #6 turnout such as Micro Engineering's C55 #6's.

If you hand-laid your #7's using a Fast Tracks set of jigs & fixtures, you would see a HUGE difference in the appearance of your long cars and engines as they traverse any "true" #7 or combination of #7's...as compared to the improperly proportioned Atlas C55 #7's.

Photo (1) - Here's a direct comparo between Atlas #7 and ME #6's...note the length between the tip of the frog to the toes of the closure points is nearly the same on both turnouts, as is the overall length:


Photo (2) - Here's a diagram of prototype turnouts and a chart of their proportions.  Note in the upper right-hand corner the direct comparo between a correctly proportioned #7 and a #6 and the huge difference in overall length:


All this means is that long cars and engines traversing an Atlas C55 #7 will look and function no better than if they were traversing ME or Fast Tracks #6's.  HOWEVER, long cars and engines will look exponentially better traversing a properly proportioned "real" #7 turnout made from a Fast Tracks fixture or hand-laid using a properly designed paper template.

This proportional problem for Atlas C55 turnouts also applies to their #5's and their #10's, and is one of the main reasons for reliability problems with their #5's, which have a much smaller diverging track radius than a "real" #5 turnout.

Cheerio!
Bob Gilmore

[mmagliaro]

Thanks, Bob.
Indeed, I did some scaling and measuring off your photo and drawing, and you are correct.

The overall length, length of point rails, and distance from the point rail tip to the frog tip should be about 30% more
for a #7 vs a #6.  But measuring off your photo, comparing the Atlas #7 to the ME  #6, those dimensions
on the Atlas turnout are only about 8% longer than the ME.

The Atlas #7 should more appropriately be considered a "#6+".   It is a little longer and shallower than #6, but nowhere near
a #7.

[craigolio1]

I never paid enough attention to notice that they were straight after the frog.  This explains very clearly why a cross over would work well on a properly built turnout, vs my HO days when I tried it with two 18" r Atlas snap switches and achieved catastrophic results!

How about that #20? MMMMMM

Rossford yard, I really like it too and plan to incorporate at least a bit of a curve into it.  It makes it far more interesting.

Craig