Let's talk radii

[davefoxx]

@Ed Kapuscinski,

As others have suggested, go as big as possible without killing aisle space and the overall track plan.  Unfortunately, the largest radius curve on my layout is 16".  But, it is noticeably the best place to watch trains circumnavigating curved track on my layout.

I, however, will buck the trend of those who have suggested that sharp N scale curves will not allow body-mounted couplers or long cars to run reliably.  On the Seaboard Central, my minimum mainline radius is 12-3/8", and I have a passing siding with a short section of curve as low as 11".  Sadly, I had no choice on a layout that began its life as a simple HCD layout.  But, you know me, I'm highballing passenger trains with 85' cars and intermodal trains with 89' flatcars through this trackwork that includes superelevation on the mainline curves and #5 and #7 turnouts.  Have you seen the length of my AutoTrain?!  So, conventional and sharp radiused curves can work, but you must be really careful when tracklaying.  Thankfully, you have more room than me, so, again, go as big as you can, without sacrificing other aspects of the layout and the room.

DFF

[C855B]

I'm using 24" minimum on mainlines, 18" on the "back in time" branchline.

Big Boys and DD's are barely acceptable on 24", looks-wise. I'm still at the point where I could rejigger the plan for broader curves, but at the expense of a lot of railroad, and the necessity of access duckunders.

[wm3798]

The line around the Beast was set as a 30" diameter/15" radius, with the scenery providing the necessary mask.



Never had an operational issue, even on a pretty substantial grade with tunnels and switches.

My helix was also 15" r, and worked great, as long as I had the switches properly set down below...

Unless you're planning run long wheelbase steam (which you're not) or a high volume of long cars (TOFC? Auto Racks?) you might want the visual of something wider, but with good easements and a nice scenic costume, 15" should be all you need given the tight quarters you're working in.

Lee

[Chris333]

I got a door so that limits me. My layout is just an inch or two below my eyes so the sharp curves don't look as bad. And I made sure passenger cars can pass each other without touching.

[randgust]

My worst-case scenario was proven when I got Atlas 89' flats with short-shank couplers and body-mounts, not enough swing or shank and they stringlined on the 13" curves anyplace before the middle of a 15-car train, lifted the car right off the outside rail edge under motion.   BLMA flats and Tranworx flats, with longer coupler shanks and body mounts did not stringline and I'm still running those.   Sold the Atlas cars as a solution after accepting I'd finally crossed the line here with what would work in practice.  Bought MT flats and those always work without a hassle, have never had an issue with those.

So....yeah....maybe.... but you're on the ragged edge.

[bbussey]

As large as you can in the visible areas.

[davefoxx]

My worst-case scenario was proven when I got Atlas 89' flats with short-shank couplers and body-mounts, not enough swing or shank and they stringlined on the 13" curves anyplace before the middle of a 15-car train, lifted the car right off the outside rail edge under motion.   BLMA flats and Tranworx flats, with longer coupler shanks and body mounts did not stringline and I'm still running those.   Sold the Atlas cars as a solution after accepting I'd finally crossed the line here with what would work in practice.  Bought MT flats and those always work without a hassle, have never had an issue with those.

@randgust,

What works for me is putting a BLMA flat (with longer couplers) between Atlas cars, so that the short couplers on the Atlas cars don't inhibit operation through sharper radius curves.  It works on curves down to 11".

DFF

[wcfn100]

I don't know when or if I'll ever have another layout, but I always test anything I'm working using a 15" radius. I'm hoping whatever I build won't have to go below that.

Jason

[mark.hinds]

My 25 cents worth, based on my smallish, unfinished layout, is:

1)  Adhere to a minimum operating radius, based on equipment considerations. 
2)  Use a larger radius in visible areas, based on their aesthetic importance. 
3)  A tighter radius is more objectionable on outside curves, and when viewed from above.  Inside curve, and near-eye-level situations are more tolerant of tighter radii.

MH

[Ed Kapuscinski]

Thanks for the great info everyone.

I did 15 and 18 on the NCR shelf (that now lives with @chicken45), and I didn't have any operational issues, but I'm definitely thinking of going bigger on the next thing if I can.

Basically, what I'm planning now is to close the loop on the Windsor St Yard layout so I can get running. Here's what I'm thinking.
[ Guests cannot view attachments ]

The yard is to the bottom, and I want to do a double sided thing. The idea is to simply "close the loop" with a minimum of fuss and muss.
I want to do a double sided thing down the center, and it looks like I can do it with an 18" radius curve going to it and then 22" and 24" to the outer loop. Since those seem to be the sweet spots, I think I can live with them.

[wcfn100]

Something I didn't see mentioned yet is to plan for easements when using smaller radii.  They won't help with the visual, but will definitely aid in operation.

Jason

[basementcalling]

Something I didn't see mentioned yet is to plan for easements when using smaller radii.  They won't help with the visual, but will definitely aid in operation.

Jason

Actually I think they help with visual too, depending on how much of the curve is the spiral vs set radii. The bone jarring gap between cars on the curve vs straight at the start and end of the curved section are the most visually insulting parts of sharp turns to my eye, so the easements help with that. And many times the central portion of a tight curve can be hidden by trees, a cut, or building.

If I were designing again from scratch, I would consider 21 inches as a minimum in visible areas instead of my current 18 with most visible curves at 19.25 or 19.5. Some of my industrial trackage goes down to 15 inches, but while that may work operationally, spotting a 73' centerbeam along a loading dock after it goes around a 15 inch curve still leaves an afterimage of said car overhanging.

In my 2 loops of hidden track I went with Kato UniTrak to ensure reliability. I cut their large radius double track concrete tie sections in 1/2 and got the 18 7/8 radius curve pieces I needed.

I'm very curious to see how N scale evolves in the minimum radius department, as I've noticed that some newer releases with body mounts or larger new engines are stating minimum radius of 11 or 12 inch curves versus the old 9.75 inch standard minimum from snap track days.

[Flagler]

I try to use 28 1/4" Radius on the main, but I mix in some 19" when needed. The track I use is 15 degrees so I need 12 pc's to to turn 180degrees. I might use 6 ,28 1/4" and  6 , 19"

[Rossford Yard]

Someone hinted at broader radius in spots and narrower in others.  On my old layout, I broadened out the visual curves coming out of my tunnel to the yard, and made the non visible part a bit tighter.  The problem is, the train, or certain kinds of cars, like Racks, slows down on the curves, even if hidden, causing some visible change of speed to the visible part of the train.  So, don't make that mistake of a compound curve.

I also used super elevation, and think a small bit of it helps performance and looks great.  Easy to do, just put 0.01 or 0.02 strips under the outside.  Doesn't have to be solid.

On my new layout, I have one Atlas C55 curved turnout in my mainline.  So, I set that curve at the 21"/16" (going from memory) so it flowed.  So, if you have any curved turnouts, it might affect your choice.

My only tips.....

[John]

I have one area thats 15" (Wheeling Jct) and it's signaled for restricted speed (15mph) .. 89" go through there ok, but don't go fast