Degree of curvature

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This article is about the measure of curvature. For other uses, see degree (angle).

Degree of curve or degree of curvature is a measure of curvature of a circular arc used in civil engineering for its easy use in layout surveying.

A n-degree curve turns the forward direction by n degrees over some agreed-upon distance. The usual distance in US road work is 100 ft (30.48 m) of arc.[1] US railroad work traditionally used 100 ft of chord and this may be used in other places for road work. Other lengths may be used—such as 100 metres where SI is favoured, or a shorter length for sharper curves. Where degree is based on 100 units of length, the conversion between degree and radius is DR = 5729.57795, where D is degree and R is radius.

Since rail routes have very large radii, they are laid out in chords, as the difference to the arc is inconsequential and this made work easier before electronic calculators.

The 100 ft (30.48 m) is called a station, used to define length along a road or other alignment, annotated as stations plus feet 1+00, 2+00 etc. Metric work may use similar notation, such as kilometers plus meters 1+000.

See also[edit]


  1. ^ Davis, Foote, and Kelly. Surveying Theory and Practice, 1966

External links[edit]

Note the variation in usage among these samples.