Curves and its type

Curves and its type

Curves are the geometrical arcs provided at the change in gradient for alignment of road.

 Necessity of providing curves

1.  To lay the road according to topography of the country.
2.  To avoid costly land.
3.  To avoid excessive cutting and filling.
4.  To avoid certain important structures.
5.  To make use of the existing Road bridges etc.
6.  To provide access to the particular place.

 Types of curve

1) Horizontal curve
2) Vertical curve

   A horizontal curve is a curve in plane to provide change in direction to the central line of road. The minimum radius of horizontal curve depends on the permissible design speed for the road. The values of minimum radii for various categories of roads in different areas, recommended by IRC.

   Vertical curves are the curves provided at the intersections of different grades in the vertical alignment of highway. This is introduced to smoothen out the vertical profile and thus to  ease off the changes in gradient for the fast moving vehicles.