Free Web Tool

Vertical Curve

Compute crest or sag vertical curve geometry — A, K, BVC/EVC, high/low point, and minimum L for design stopping sight distance.

Inputs

Curve Type

Length L (m)

Grade g₁ (%)

Grade g₂ (%)

PVI station (m)

PVI elev. (m)

Design SSD (m)

Method (AASHTO)

A = |g₁ − g₂| (% algebraic difference).
K = L/A; high/low point at x = (g₁/A)·L from BVC.
Crest min L for SSD: L = A·S²/100·[2·√h₁+ √h₂]² (or simplified L = A·S²/658).
Sag (headlight): L = A·S²/(120 + 3.5·S).

Results

A = |g₁−g₂|—

K-value—

BVC station / elev.—

EVC station / elev.—

High/Low point at x—

Min L for SSD—

Status—