Implementation - Profile Grade

There are three options for inputting vertical profile: input PI and curve K factor; input PI and curve length; input profile points for curve fitting. For pavement drainage design, normally a minimum of 5 PI points and three curve data are required to describe a vertical curve which contains a sag point and two crest points. The curve data can be input as K factor or curve length or points on curve.

When user input points on curve, program will use least square method to fit a second order polynomial curve. Points on curve can be classified into point on straight slope (ID=1) and point on curve (ID=2). The first point on curve will assigned as PVC and the last point on curve will be assigned as PVT. If only a curve is specified, the first point should have ID of 1.

PI points should be arranged from lower station to higher station. Each PI point requires station and elevation data. The K factor of vertical curve is the length of the vertical curve divided by the algebraic difference of the slope of the tangents on each side of the curve divided by 100.

  K = L/(100*A)
where:
  L=Vertical curve length
  A=Algebra difference of the slope of the tangents of the curve