Why does the Czech Cubic Parabola report a leading transition value a few hundredths greater than what was inputted?

Holly Herring — Fri, 14 Jul 2017 15:44:45 GMT

Current Revision posted to OpenRoads | OpenSite Wiki by Holly Herring on 7/14/2017 3:44:45 PM

Product(s):	Rail Track
Version(s):	08.11.07+
Area:	Geometry
Original Author:	Holly Herring, Bentley Technical Support Group

Question:

When I create a Czech Cubic Parabola, and assign the leading transition as a whole number (for example 40-m), why does the Review Horizontal Alignment report list my Length a few centimeters greater than the whole number with the whole number listed in parentheses to the right of it (for example 40.018 (40.000))?

Assign leading transition as 40-m

Reports 40.018 (40.000)

Answer:

The user defines the length of the Czech Cubic Parabola as the length along the tangent (40-m). The primary difference in the Czech Cubic Parabola to others is that it is defined by the length along the spiral's tangent, rather than the length along the centerline. The software computes and reports the length along the axis (40.018-m), and puts the length along the tangent to the right in parentheses.