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Calcimator

Vertical Curve Calculator

Calculate parabolic vertical curve elevations, K-value, high/low point, and minimum length for crest and sag curves using AASHTO standards.

Inputs

%
%
ft
ft
ft
mph

Results

Curve Type

Crest

K-Value

120

Grade Difference (A)5%
Min. Length (AASHTO)557 ft
Length Adequate?Yes — meets AASHTO minimum
BVC Station4,700 ft
BVC Elevation491 ft
EVC Station5,300 ft
EVC Elevation494 ft
High/Low Point Station4,880 ft
High/Low Elevation493.7 ft
R-0.01
How to Use This Calculator
  1. Enter the incoming grade (G1) and outgoing grade (G2) as percentages.
  2. Set the length of the vertical curve L in stations (100 ft each).
  3. Input the PVI elevation and station.
  4. Review the BVC and EVC stations and elevations, and the High or Low Point location.
  5. Use the Elevation at each station table to set grade stakes in the field.

What each input means

Incoming Grade (g₁)
Grade of the approaching tangent in percent. Positive = uphill, negative = downhill.
Outgoing Grade (g₂)
Grade of the departing tangent in percent.
Curve Length (L)
Total length of the vertical curve.
PVI Station
Station of the Point of Vertical Intersection (PVI).
PVI Elevation
Elevation at the PVI.
Design Speed
Design speed for minimum curve length calculation per AASHTO.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Incoming Grade (g₁) = 3, Outgoing Grade (g₂) = -2, Curve Length (L) = 600, PVI Station = 5000 = 6 input(s) provided
  2. Calculate Curve Type
    Curve Type
    Crest = Crest
  3. Calculate K-Value
    K-Value = K
    120 = 120
  4. Calculate Grade Difference
    Grade Difference = A
    5 = 5
  5. Calculate Min. Length
    Min. Length
    557 = 557

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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