Curb Return Design - Plane Method

[raydefan]

I am looking at the County of Riverside "Plane Method Curb Return Design" worksheet, and think I have found an error in it. Does anyone have a reference that explains in detail how the plane method formulas are derived? A website link would be nice, but I'll take a book reference as well.

Thanks,

Jeff

 

[RWF7437]

Why not ask Riverside County ?