Turn Radius

[AGSB]

When reading a track plan and also seeing curved track marked with a radius of 18", 22" or whatever dimension, just where do you measure the radius from? I am laying flex track on a cork roadbed and want draw out the curve using a tramel. So does the drawn arc indicate the inside rail, the centre of the rail (centre line of the 2 cork halves) or the outside rail?

I have been all over the web and can't find any mention of this.

[mhampton]

Track radius is measured at the center line of the track.

[AGSB]

Thanks, that's what I thought I had read somewhere, but just wanted to check and make sure.  You can always cut something shorter but you can't cut it longer once it's cut.

[GG1onFordsDTandI]

The safer answer is, even if new, that it depends on track type, gauge, and manufacturer. Some old ones were even measured at the roadbed/tie edges. 150yrs of model rr's yielded a wide variety!

[jward]

that just confuses the issue. at least in HO and N scales, the convention has been radius is determined at the track center, and it's been this way for at least 50 years. in many layout plan books they tell you to checque your radii by measuring from the centerline where the nail holes are.

[GG1onFordsDTandI]

that just confuses the issue. at least in HO and N scales, the convention has been radius is determined at the track center, and it's been this way for at least 50 years. in many layout plan books they tell you to checque your radii by measuring from the centerline where the nail holes are.

No scale was specified, this is the general forum, what I wrote was not wrong, or misleading. N and HO are not the only two scales.
P.S. I also thank you for the response. I will take note of your advice on N and HO measuring. 

[NarrowMinded]

The key is in the questions  "reading a Trackplan" and "laying flex track"

Center line of track.

NM-Jeff