Okay, I am a returning Nscaler, but this applies to all of us when we are designing/building our layouts. We have the innate desire to have as much track possible on our railroad to show off our cars and especially our locomotives. However, the radii that most cars will traverse is ridiculously tight compared to what looks good. Sure we can run 85' passenger cars and 6 axle PA/PB Super Chief on a 9 3/4" radius, but the overhang is ridiculous and can even cause your cars to sideswipe scenery, buildings and other trains. And it makes our layouts seem "toylike" to our viewers/guests. Solutions? Well, first off [sounding like Barstow Rick here, but he is right], sacrifice a bit of track to use as large a radius as you can actually fit on a layout. In building my N scale Gorre & Dapetid, I was blessed with a ton of good advice on how to make it better running. If I used old J.A.'s plan as designed, it would have 7" radius turns on it. Instead, by going to N scale, I was able to make the minimum radius on my mainline an 11", which makes all of the cars look better, and also by adding the length was able to go from a 4% grade to a 2%. But even with that my 85' passenger consist looks wrong. So what else can you do? Shorter cars & engines help. By picking up the older Model Power and Bachmann passenger cars which are 65' and 60' respectively, the image and clearance problems are helped. Even these, behind a 4-6-2 are pushing good clearance limits, but by using view blocks on most of my curves, this can be minimized. The rest of the rolling stock is limited to small 2-8-2s and 40' cars on the layout. So sadly, I decided to limit my big passenger trains to when we have T Trak shows, but then those long cars and engines really do get to show off and look good on the 13 1/2" curves. Below is a bird's eye view of some 70' passenger cars on a 11" radius curve, yes, they fit, but don't look very good doing it.
You can also limit the number of places where longer cars look out of place by making an oval more like an ellipse, with broader curve entrance/exits and sharper apexes. This works even with sectional track. It takes some length out of the straights, but is usually a good trade. The shorter, sharper apexes can then be hidden or disguised by view-blocking scenery more easily. And of course, raising the layout to nearer eye level when in use (consider whether you will typically be seated or standing) helps hide the sharp curves and their effects on trains with long cars. You may want to be able to lower the layout when working on it, and raise it while running/watching trains. One of those motorized seated/standing desks or work tables would be handy for small layouts. Check your local used office supply resellers to see if they have any deals on them.
I like the comment about raising the layout to eye level inhibiting the visibility of shorter curves. I'm an HO-er, but I think equating the radii 2:1 is valid, since both HO and N are largely about "real" scale. IMHO, the shorty cars on the 11-inch equate to 22-inch radii in HO - and the photo doesn't look too bad from my perspective. I've seen much worse, like my Rivarossi Big Boy running around 18-inch curves on the layout I built as a teenager. Honestly, even 18/N and 36/HO radii curves are still woefully smaller than anything in real life. Yet, most of us have to live with them if we want the trains to enjoy continuous running or have any sort of travel distance. Curves should be shoved to the background by using much longer straight runs. You're better off with a giant, around-the-room oval and hiding the curves with view blocks and/or scenery. It lets the straights take center stage with the most visibility. At the same time, maybe you can use those 11/N or 22/HO curves and not worry about it if they're largely hidden or in the background. That said, most large HO locos and HO rolling stock these days recommend 24 inch minimum, which would equate to 12 inch radii in N.
Heck, if you want a Unitrack single-crossover between two straight tracks, that's 19R in N. Good points... It's important to consider the scale distance of the viewer from the train/track as well. There are relatively few 1:1 scenic lookouts from which you can see as much train and track as we typically show on our layouts. Perhaps that also has a lot to do with selective compression on our layouts. Also, HO:N is actually ~1.84:1, so a 24R HO curve is a hair over 13R in N. Most rolling stock looks a lot better on 13R (or 13.75R in Unitrack) than on the minimum radius of 9.75R recommended by the manufacturer(s). To be fair, the mfg recommendations are for operability, not appearance! Still, that could give us an idea of how low we could go with the radius at the apex of a curve, to give us room to broaden the radius of the rest of the curve (i.e. a continuous easement from end to apex, and vice versa).
