# O-Gauge track dimensions



## 24forsure (Jan 13, 2015)

Hello everyone! I'm new to the forum, so without searching 33 pages to find a related thread, here is my question. O-Gauge curves are designated as 031, 042, 054, etc. I know this is a designation of the diameter of the curve, but I have never been able to figure out where this is measured from. I've heard center rail to center rail, to the outside edge of the ties, etc. What is the correct answer? Getting ready to retire, and start that layout I 've always wanted. Need this answer to get started on my plan for a 6 x 12. Thanks to anyone who can settle this for me !!


----------



## rkenney (Aug 10, 2013)

Tubular track is the diameter measured from the outside edge of the ties.

See this illustration reprinted for years in the Lionel instruction manuals:










I don't own the other track types so I couldn't positively say where they are measured from.









It was done this way so that you could anticipate the board/space needed to accommodate a particular curve. You already have the largest dimension.


----------



## 24forsure (Jan 13, 2015)

Thanks Bob, that was my conclusion also. Believe it or not, the actual Lionel website told me center rail to center rail, but when I loosely assembled the track, I came up with your answer. Thanks for verifying, now I can start my plans.


----------



## tjcruiser (Jan 10, 2010)

I'm saying this from fuzzy memory, but I think there's an exception or two to Lionel's O diameter reference rule. We've discussed this in prior threads. I'll have a look.


----------



## 24forsure (Jan 13, 2015)

Just realized that Fastrack is center rail to center rail. (036=36")


----------

