A Little Help with Radius Dimensions

Model Railroader Layouts and layout building
1

If I have a 28" radius…what is

1.) My outside dimension if I lay a track 180 degrees?

2.) What would that outside radius be with cork roadbed included?

I’m trying to figure if the dimensions I read in the books is centerline, I.D., or O.D…

Thanks for helping an obvious ‘idjet’. :))

Mike

2

The dimensions on plans are the centerline radius.

3

Since you didn’t specify scale, I am going to assume HO (based on your stated radius, which is far larger than usual for N.)

  1. 28" radius times 2, plus 28mm (length of HO ties - honest,) or 57 3/32 inches.
  2. Assuming the cork is 2 inches wide, 58 inches to the edge of the cork.

Not included in the above was the additional width required for a proper spiral easement at each end of the curve - which would add from 3/4 inch to 1 inch to the total width required for a 180 degree “turn back at the end of the table” curve. OTOH, most rolling stock would be happier with a 26 inch radius with proper easements than with an un-eased (AKA jerk-whiplash) 28 inch radius. Looks better, too.

Chuck (modeling Central Japan in September, 1964)