Unsymmetrical Parabolic Curve Solver

Enter the back tangent grade, forward tangent grade, total curve length, and distance x from PVC to PVI. Select the known point as PVC, PVI, or PVT, then enter its station and elevation.

Inputs

g1 back tangent (%)

g2 forward tangent (%)

L (m)

Known station (m)

Known elevation (m)

Distance L1 from PVC to PVI (m)

Distance from PVC to point for elevation (m)

PVC--

PVI--

PVT--

L1, L2, and g3--

Elevation at distance from PVC--

Maximum/minimum point--

Selected known pointPVC

Grades are percent grades. Click a point on the figure to use that point as the station/elevation input anchor.

High/low point--

External ordinate H--

Grade change rates--

Summary of Formulas

L = L1 + L2

H = (g1 - g2) L1 L2 / (2L)

g3 = g1 - 2H / L1 = g2 + 2H / L2

Here L1 is the PVI location measured from PVC, and L2 = L - L1. Use grade values as decimal grades in formulas; the input boxes accept percent grades and convert them automatically.