Horizontal Curve Calculator

Calculate horizontal curve parameters for road design and surveying applications. Enter any two parameters to compute the remaining values.

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Calculation Results

Radius (R):
Degree of Curve (D):
Central Angle (Δ):
Tangent Length (T):
Chord Length (C):
Arc Length (L):
External Distance (E):
Middle Ordinate (M):

Horizontal Curve Diagram

Frequently Asked Questions

What is a horizontal curve in road design?

A horizontal curve is a circular arc that provides a transition between two straight sections of a road or railway. It allows the path to change direction smoothly rather than at an abrupt angle.

How do you calculate the degree of a horizontal curve?

The degree of curve (D) is calculated using the formula: D = 5729.578/R, where R is the radius of the curve in feet. For metric units, the formula becomes D = 1746.38/R where R is in meters.

What is the difference between a simple curve and a compound curve?

A simple curve is a single circular arc with constant radius, while a compound curve consists of two or more simple curves with different radii that join together in the same direction.

When should I use a horizontal curve calculator?

This calculator is useful for civil engineers, surveyors, and road designers who need to determine curve parameters for highway design, railway alignment, or any project requiring smooth directional changes.