What is the overall meaning of Radius?

[quryous]

When your company list track as, say, 22" radius, to where are they measuring that? -
From the center of the circle to the inside edge of the roadbed, to the innermost rail, the center between the rails, the outermost rail, or the outermost edge of the roadbed? Thank you.

[ABC]

22" radius means 22" inches from the exact center of the circle to the midline of the track.