Spectra Precision Survey Pro v4.6 Ranger Reference Manual - Manual (Page 409)

Curve Menu
R-401
Spiral
Curve Spiral .
The Spiral screen will compute the details of a spiral curve, given the
spiral length and radius.
Spiral length: is the length of the spiral curve.
Radius: is the circular curve radius.
Solve : computes the details of the spiral
curve.
Layout… : opens the Spiral Layout screen
(Page R-402) where the location of stations on
the spiral curve can be computed.
Traverse… : opens the Traverse on Spiral
screen (Page R-403).
Results
X of Throw: is the distance along the tangent where a perpendicular
line intersects with the radius point.
Y of Throw: is the minimum distance between the tangent and the
extended circular curve.
X: is the distance from the TS to the SC along the tangent.
Y: is distance from the SC to the tangent.
Delta: is the angle between the tangent, and the line between the PI
and SC.