Types of curves provided on hill road are as follow:

(1) Hair pin bend curve: The curve in a hill road which changes its direction through an angle of 180$^\circ$ or so, down the hill on the same side is known as hair pin bend curve. This type of curve should be located on a hill side having the minimum slope and maximum stability. It must also be safe from view point of landslides and ground water. Hair pin bends with long arms and farther spacing are always preferred.They reduce construction problems and expensive protection works.

(2) Salient curve: The curves having their convexity on the outer edges of a hill road are called salient curves. The centre of curvature of a salient curve lies towards the hill side. This type of curve occurs in the road length constructed on the ridge of a hill. The bend so formed at the salient curve in a hill road is known as corner bend. Salient curves are very dangerous for fast moving traffic. At such a curve or at corner bend, the portion of projecting hill side is usually cut down to improve the visibility

(3) Re-entrant curve: The curves having their convexity on the inner edge of a hill road are called re-entrant curves. The centre of curvature of a re-entrant curve lies away from the hill side. This type of curve occurs in the road length constructed in the valley of a hill. These curves are less dangerous as they provide adequate visibility to the fast moving traffic. At such curves, the parapet wall is provided only for safety of fast moving traffic.