1. Curves
During the survey of the alignment of the project involving roads or railwayes,the direction of the line may change due to sum unavoidable cercumstance.For this reason the posibility of vichele to run easily among the road or track,the two stright line are connected by an arc ,which is known as curve.

2. CURVE Horizontal curve Verticle curve Simple curve Compound curve
Revarse curve
Transition curve
Lemniscate curve

3. DEGREE OF CURVE The angle a unit chord of length 30m subtends at the centre of the circle formed by the curve is known as the degree of the curve.When the angle is 1 degree ,it is called one degree curve.When the angle is 2 degree it is called two degree curve.it is calculated that the radius of one degree curve is 1719m. A B R D
Unit chord

4. Relation Between Radius And Degree Of Curve
R = 1719/D

5. superelevation
When a particle moves in a circular path ,then a force acts upon it ,and tends to push it away from the centre.Similarly,when a vehicle moves in a circular path, then a force acts upon it ,and tends to push it away from the centre.This force is known as centrifugal force. In order to solve this problem ,the outer edge of the road or rail is raised is known as superelevation.

6. Equation of Superelevation
P= wv²/Rg h
W sinµ
b or G
W cosµ W

7. Simple circular curve: When a curve consist of a single arc with a constsnt radius is called simple ircular curve

8. Compound curve: When a curve consist of two or more arces with different radius is called compound curve.

9. Reverse curve:When a curve consist of two arc bending in opposite direction is called reverse curve.There radious may equal or different

10. Transition curve:A curve of variable radious is called transition curve. In railwayes such a curve is provided on both sides of a circular curve to minimise superelevation.

11. Lemniscate curve: Lemniscate curve is similer to a transition curve
Lemniscate curve: Lemniscate curve is similer to a transition curve.And it is generally adopted in city roads where deflection angle is very large.