Vertical Curve Calculator

Form

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Results

Elevation of PVI

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Elevation of EVC

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What is Vertical Curve?

Estimate elevations along a parabolic vertical curve connecting two grades.

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How to Use This Calculator

  1. Enter or select Elevation of BVC, Initial gradient (g1), Final gradient (g2), Length of curve.
  2. Check the unit beside each measurement. For a percentage or rate, use the scale and time period stated in the form.
  3. Choose Calculate, then compare the output with the formula and example below. If you change a value or option, calculate again to update the result.
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Formula Used

Elevation(x) = BVC elevation+g₁x+(g₂−g₁)x²/(2L)
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Variables Explained

InputWhat it means
Elevation of BVCUse the measured or stated value for this item, with the unit or category shown beside the field.
Initial gradient (g1)Use the measured or stated value for this item, with the unit or category shown beside the field.
Final gradient (g2)Use the measured or stated value for this item, with the unit or category shown beside the field.
Length of curveThe measured end-to-end distance of the section being calculated.
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Worked Example

With BVC=100 m, g₁=0.02, g₂=−0.02 and L=100 m, the midpoint elevation is 100.5 m.

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Why Use This Calculator?

Use the result to put measurements on a common basis before comparing them or estimating quantities. The original measurement precision still limits the precision of the answer.

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Common Mistakes

    • Use grades as decimals in the equation; x is measured from the beginning of the curve.
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Frequently Asked Questions

When should I round a measurement?

Carry the measured values and conversion factors through the calculation first. Round the final result to a precision justified by the original measurements.

Why can a supplier’s quantity differ?

Measurement conventions, nominal sizes, density assumptions and purchase rounding can change a practical quantity. Compare the units and assumptions before comparing the numbers.

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Sources & References