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In 3-rail lingo you're using O81 for your through track, so to match up with Atlas O metrics, you would use O72 (or 36" radius) for the turnout portion to maintain Atlas customary track separation.  You could obviously go much narrower with the turnout radius (34", 32", etc.) with the attendant equipment problems.  I'm just not sure how much wider you could go (37", 38", etc.) without creating custom switch construction problems?  I bet somehow this has to be determined by curved frog design.


Chuck, understood.  Brad can make the turnouts to fit, I'm trying to determine how larger he can make the diverging route, other than what we see commercially as a standard.  I hope he can go larger than 36" radius even though most of the engine that will be using this piece of track are 2-8-0 types and can run on 36" radius, I sure don't want to go below that.

Being I run 3-rail equipment (BPRC of course) on code 148 track there's always something to look out for, but the 2 dozen or so #5 switches Brad has made me so far have worked perfectly, so I don't see him having a problem coming up with something I can use.

I would try making them myself but my last (and final) attempt was a dismal failure in the end, especially when I got my 1st Signature Switch turnout.  No looking back after that.

Thanks guys!!!

Problem is I already have the siding in place, using 2 #5 switches which use up a lot of the space on the siding.  If I could replace them with 1 lefthand and 1 righthand curved switches back to back it would free up some space.

The area I'm talking about is in the lower left corner of this diagram.  The current siding track there is Atlas 40.5" sectional.  Pulling out the 2 #5 switches and replacing them with 2 curved switches should do what I want without having to redesign the whole corner.  Even if I have to rip up the entire siding it'll still give me a better result I believe.

Now that I look at the plan, the final result doesn't quite match it anyway but it's close enough for you guys to understand what I'm talking about (I hope!).

PLAN H 2019


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  • PLAN H 2019

I can't say I understand what your trying for exactly that you don't already have for the most part. But bare in mind that these curved switches take up a fair amount of space that may end up being to much for that situation. For  example one of mine is about 23" long, and even at that overall length the separation is not wide enough to let a train safely pass for several more inches. But I will keep watching your postings on this situation, and the lightbulb moment may happen...or may not


Bob, I think what I'm aiming for is to move the present switch at the top left farther away from the main in order to give me more track between the main and the spur.  The #5 switches are approx 21" long.  I'm hoping that 2 curved switches will give me more options of where they go in the siding.

Now that I look at the plan and what I actually have, I realize I had made significant changes a while back.  The switches currently used are at the ends of an almost 90 degree piece of curved track.  Using curved switches in place of the 90 degree section of curve will give me what I want.  Here's a photo of what it looks like now.  Sorry for the long shot but you can see the ground throws denoting the ends of the switches on either side of the depot:


Once I hear from Brad I'll see.  I wonder if he would send me a template or drawing of the curved switches so I could see if they would do what I want, or at least give me the dimensions so I could plot them out???


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Bob, after looking at your plan and your explanation, I'm feeling a lot like flanger above.  So, I used SCARM and Atlas track (a few pieces of O81 and a few pieces of O72 overlaid) to "create" a very poor replica of a custom curve switch, and then I imported two Ross curved switches into the same work table.  My work seems to show that the length of the switch will have to be much longer than expected to achieve track (and train) separation when the two switch radii are nearer to each other in size.  Further, I can see how a custom curve might be helpful for the siding at the lower end, but I really don't see all that much benefit for the siding at the upper end.

So, I too will be waiting to see just how you do this and how much the benefits are.  Please note that you can use SCARM for free up to 50 pieces of track.  I would really like to see a before and after plan for that lower left corner to truly understand your goal.


Curved Switch Comparisons-2

AND, your new post just before mine now has me really confused.  On your plan, the station is outside the trackwork, but in your picture, it seems to be inside the trackwork.  Does this mean switch locations have also changed from the "plan?"


Last edited by PRR1950

A #5 definitely does not need to be 21" long. Back to back like that you can trim the tail ends til theres not much more than a rail joiner between the tips of the moving points (or if you hand lay it, next to nothing).  I think the minimum length you can get out of a #5 is around 16". Once you clear the frog, nothing stops you from immediately bending a 36" radius right into the diverging leg. I suspect a curved switch will be even longer than a straight one, and you will eat a lot of space before the clearance point (of note though, that a number 5 is a 50" radius equivalent). If its really just a siding, a #4.5 would be a little sharper of a frog, but the length savings isnt all that much.

Last edited by Boilermaker1

I had a discussion with Atlas at York (4 years ago) about additional track sections.  I didn't make the next Yorks due to Hurricane Michael and Covid.

They were looking at #4 turnout, O90/O72 curved switch, O63 switch, and a #5 double crossover.  The curved switch would be my highest priority.

I would love Atlas to comment on these.


Sorry for the confusion folks, I forgot I made changes after the plan was drawn (using the old Atlas software which I can’t get to work anymore).

My purpose is I want to try to get more distance between the switch (that you see just to the bottom of that horizontal black bar [wall])  and the switch going to the Portsmouth Lumber Company. I need more track there or I have to do a run around or leave part of the train on the mainline when switching. I may have to take out the siding going to the Seaboard Team track but that is a last resort.

It never occurred to me that a curved switch may be too long, I hate it when that happens!

Custom curved turnouts have made difficult jobs work out for me many times.  The short answer is to shut down your computer and disregard your track planning systems.

I have laid out many junctures of right of ways with total disregard to any fixed available turnouts.

I fix the track as to how I need it to run then get some brown wrapping paper and a big brown crayon and trace the location.  I then roll it up and send it to Brad.  Brad spends some time on his keyboard and creates a CAD which he sends me.  I in turn email it to FedEx which prints it out 1:1.

Then I position it in place over my staged track to confirm fit.  Then Brad gets the go ahead to make the plan.

Brad  can build anything.  Period.  He has no limits.  For example I needed a 76" radius curved turnout throat that went straight at a #5 frog.   Below, lower left.

Junction 001

We also needed a diverging track to come off a 72" radius curve, cross an east bound track then join a west bound track all in one piece.  Shown below.

Junction 007

On another occasion a 4 track staging yard needed a ladder track to fully develop in under 90 degrees of  72" radius.  This meant that the points had to be positioned to less than 1/2" from the frog.  Brad made a custom arrangement of half turnouts which were much like the early Roco switches.  Shown below.

72 inch 60 inch curved ladder 00372 inch 60 inch curved ladder 004IMG_6929

There was a need for an asymmetrical wye where a sharp curve had to leave a wide radius curve to serve a coal ramp.  Again below:


One of Brad's specialties is a curved crossing on a curve.  My most recent peninsula required crossing a curved outside track to gain connection with an inside curved track. which required a double curved diamond joining a asymmetrical wye turnout with  both curves on a spiral easement.

WBrad x-ing 3What I neededBrad crossing 4Brad's CADBrad x-ing 2FedEx deliveryBrad X-ingInitial install

As far as curved turnouts go, Brad can make anything.  He works outside the box.

lift out overall 005


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  • Junction 001
  • Junction 007
  • 72 inch 60 inch curved ladder 003
  • 72 inch 60 inch curved ladder 004
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  • IMG_9001
  • Brad x-ing 3
  • Brad crossing 4
  • Brad x-ing 2
  • Brad X-ing
  • lift out overall 005
Last edited by Tom Tee

Bob, if I may suggest.  Remove all #5 turnouts in the lower quadrant.  After coming across what may be the stair case come off the main line and go into a three way wye.  Left leg goes back to the main, the middle and right leg feeds the mill and foundry.  Coming off the tail of the three way points, a LH curved turnout will give you a track into the Seaboard team track and a connecting track back into the main line.  Consider NOT using the full size 20" Atlas #5 for rejoining the main.  That one product uses a lot of real estate.

I would suggest to install a curved turnout in the five o'clock position of the curve on the bottom right hand of your track plan above.  Understand the Atlas #5 is sized for newby's to use the Atlas track planner which replaces two 10" pieces of snap track.  Only the far right hand #5 below is original full size.  A full size #5 can be clumsy.

IMG_0084Check out the surgery


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  • IMG_0084
Last edited by Tom Tee

I think Tom's suggestions above are based on the 2019 version of your plan.  The old Atlas track software was just re-branded SCARM software, so if you'd like to post an updated view of that lower left hand corner as it's now implemented, you can use SCARM for free (up to 50 pieces of track).  Probably only important to place the critical pieces like switches if you hit the 50 piece limit before completion.  Please remember to export your newer version as a .bmp file (so those without SCARM can follow along) and then attach both the SCARM file and the .bmp file to your post.


@Tom Tee posted:

Custom curved turnouts have made difficult jobs work out for me many times.  The short answer is to shut down your computer and disregard your track planning systems.

I have laid out many junctures of right of ways with total disregard to any fixed available turnouts.

I fix the track as to how I need it to run then get some brown wrapping paper and a big brown crayon and trace the location.  I then roll it up and send it to Brad.  Brad spends some time on his keyboard and creates a CAD which he sends me.  I in turn email it to FedEx which prints it out 1:1.

Good planning!!!

I'll have to download SCARM...again.

I did freehand what the current plan looks like, not to scale but close enough to show what is currently there.  49.5" radius on the single mainline and 40.5" radius on the inner track, #5 switches throughout:

using curved switches20210725_10354558

The blue is the outer edge of the layout, the black is the current track location, the circle is my problem area.

I need to lengthen the problem area, otherwise I have to leave part of the train on the mainline when switching the Portsmouth Lumber Yard (lower spur), the Seaboard Team Track (upper spur) isn't an issue.

Looking at it further, I think a single righthand curved switch is what I need, located at the end of the switch for the Team Track.

I wanted to base my layout on the Seaboard Portsmouth Sub-Division, this is VERY, VERY loosely based on that (and I mean very!).  It was dark territory, using train orders I believe with only a couple of trains each day.  Being I'm the sole operator and run only 1 train at a time, leaving cars on the mainline is all good in my mind (it is my RR after all), but I would like to be a little more prototypical in operating the layout, that's why I want to put a curved switch in place.

It wouldn't HAVE to be placed at the end of the Team Track switch, but that would give me the maximum length in that circled area.


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  • using curved switches20210725_10354558

Lenz makes a curved turnout with a 40.5" inner radius That is fully compatible with Atlas track.

You should be able to make it fit your application.

If that doesn't work I strongly recommend Brad at Signature Switch.  He has done several specials for me that

I just could not get right when handlaying on my own.  I'm fine with simple turnouts but curved crossovers,

crossings and complex trackage are Brad's strong points.

Last edited by Jim Scorse

Thanks Jim and Tom!

Tom, thanks but don't need anymore #5s, the 2 dozen I had Brad make me are doing the job nicely.  Not sure I could use them anyway being all my equipment uses 3-rail wheels.  Brad made the switches specifically for 3-rail wheels, I have tried converting some of my rolling stock to 2-rail but with the deeper/wider/longer flangeways in the switches they just don't work.  It may be some of my trucks are not designed as well as others but at this point I don't feel like experimenting anymore and know the 3-rail wheels/truck combos work fine on the code 148 2-rail track.

A single righthand curved switch that matches Atlas 40.5" radius track should be all I need if the diverging track isn't too tight a radius.  Hopefully I'll hear from Brad this week.

I'm just thinking out loud here, but it seems to me that the problem for which you are seeking a fix is a combination of train length, proximity of lumber yard switch location to the passing siding entrance/exit switch, and, perhaps the fact that the passing siding does not parallel the main line better, making a lesser use of available real estate.  Wouldn't a simpler (and cheaper) solution be to just put both #5 switches back-to-back (one facing point and one trailing point) in the straight section of your passing siding?  Then you would have 3 curves heading down/up the right hand side (mainline, passing siding and lumber "branch") with about an equal amount of space between the industry switches and the passing siding switches.  I can see that fitting 2 #5 switches on the short side of your plan might be a problem, but as Tom Tee suggested, they can be cut quite a bit and just might fit then.


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