# Types of curves found in Roads? A curve simply belongs to an arc that attaches two straight lines. These lines are segregated with some angle known as deflection angle. It happens under the condition where the alignment of a road way or rail way alters its direction due to uncontrollable objects or conditions.

The object ranges from a hill or a lake or a temple etc. Therefore, a curve is essential for the smooth running of the vehicles at this point.

Types of Curves in Alignment of Highways: Normally, the following types of curves are mostly found:

a. Horizontal curves and b. Vertical curves

Horizontal Curves: The curve arranged in the horizontal plane of earth is known as horizontal curve. In adjoins two straight lines which situate same level but contains various directions.

The following types of horizontal curves are available :-

1. Simple circular curve, 2. Compound curve, 3. Simple circular curve, 4. Compound curve, 5. Reverse curve, 6. Transition curve, 7. Spiral, 8. Lemniscate

Simple Circular Curve: Simple circular curve stands for normal horizontal curve that attaches two straight lines through constant radius.

Compound Curve: By amalgamating two or more simple circular curves having dissimilar radii, a compound curve is formed. Under this situation, both or all the curves remain on the equivalent side of the common tangent.

Reverse Curve: If two simple circular curves which twist in opposite directions and meet at a point, the reverse curve is developed. This point is known as point of reverse curvature. The center of both the curves is situated on the opposite sides of the common tangent. The radii of both the curves are equivalent or different.

Transition Curve: A curve that contains inconsistent radius is known as transition curve.

It is normally arranged on the sides of circular curve or among the tangent and circular curve as well as two curves of compound curve or reverse curve etc. It’s radius differ from infinity to the radius given for the circular curve.

Transition curve allows ongoing introduction of centrifugal force with gradual super elevation which arranges comfort for the passengers in the vehicle devoid of sudden jerking.