Types of curve

TYPES OF CURVES:- 1. HORIZONTAL CURVES

i. Simple circular curve

ii. Compound curves

iii. Reverse curve

2. VERTICAL CURVES

i. Summit curve

ii. Valley curve

HORIZONTAL CURVES:

(i) Simple circular curve

(ii) Compound curve

(iii) Reverse

(i) Simple circular Curve:

A simple curve consists of a single arc of a circle connecting two

straights. It has radius of the same magnitude throughout. In fig. below; T1 D

T2 is the simple curve with T1O as its radius.

2

HORIZONTAL CURVES:

(i) Simple circular curve

(ii) Compound curve

(iii) Reverse

(i) Simple circular Curve:

A simple curve consists of a single arc of a circle connecting two

straights. It has radius of the same magnitude throughout. In fig. below; T1 D

T2 is the simple curve with T1O as its radius.

2

HORIZONTAL CURVES:

(i) Simple circular curve

(ii) Compound curve

(iii) Reverse

(i) Simple circular Curve:

A simple curve consists of a single arc of a circle connecting two

straights. It has radius of the same magnitude throughout. In fig. below; T1 D

T2 is the simple curve with T1O as its radius

T1O is the radius of curve=R

(ii) Compound Curve:

A compound curve consists of two or more simple curves having

different radii bending in the same direction and lying on the same side of

the common tangent. Their centres lie on the same side of the curve. In fig.

below, T1 P T2 is the compound curve with T1O1 and PO2 as its radii.

(iii) Reverse (or Serpentine) Curve:

A reverse or serpentine curve is made up of two arcs having equal or

different radii bending in opposite directions with a common tangent at their

junction. Their centres lie of opposite sides of the curve. In fig. below T1 P

T2 is the reverse curve with T1O1 and PO2 as its radii

Reverse curves are used when the straights are parallel or intersect

at a very small angle. They are commonly used in railway sidings and

sometimes on railway tracks and roads meant for low speeds. They should

be avoided as far as possible on main railway lines and highways where

speeds are necessarily high