Just as a matter of interest......or not.
A "sweeping 72" radius curve, in HO, is a 10.5 degree curve in "prototype".
A "not so sweeping 16.6" radius curve, in HO, is a 45 degree curve in "prototype".
The Uintah Railway, 3' gauge, in Baxter Pass, had a 66 degree curve.
*Degree of curve is...