Vertical Curve Length Using Passing Sight Distance Calculator

Calculate the Vertical curve length using passing sight distance with our free online tool using the input parameters: Passing Sight Distance, Initial Grade, Final Grade

Determine the minimum length of a vertical curve based on passing sight distance, initial grade, and final grade. Calculate the optimal curve length for safe and efficient road design.

Passing Sight Distance
Initial Grade
Final Grade
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    1 Number of calculations

    Lm = \frac{{S^2 \times (g_2 - g_1)}}{{864}} \quad \text{for } S < Lm
    Lm = 2S - \frac{{864}}{{g_2 - g_1}} \quad \text{for } S \geq Lm


    • Lm: Value of Lm (minimum curve length)
    • S: Value of S (passing sight distance)
    • g1: Value of g1 (initial grade)
    • g2: Value of g2 (final grade)

    The calculator uses the formula for calculating the minimum curve length (Lm) based on the passing sight distance (S), initial grade (g1), and final grade (g2), using the given equation.