Hi,

I am a beginner railroad modeler. I have a very basic question.  When using 22'' curved tracks,  is the inner radius 22" or is it the outer radius that is 22"?

I am trying to layout my tracks on a 4' X 8' board. Should I use a 22" track or 18" track? I plan on doing some scenery so I am trying to estimate how room I will have to work with on either side of the outer edges.

Thanks for your help

- SC