How to measure different types of curves in roads

There are two types of curves in road construction which range from horizontal curve and vertical curve.

Horizontal curve - This type of curve offers a passage among two tangent strips of roadway that facilitates a vehicle to settle a turn at a gradual rate in spite of a sharp cut.

The horizontal curves are categorized as follow : Simple Curve, Compound Curve, Reverse Curve, Transition Curve

Simple Curve - A simple arc is arranged in the road to set a curve among the two straight lines.

Compound Curve - Set of two simple curves which are joined together to curve in the equivalent direction.

Reverse Curve - Set of two simple curves which are joined together to curve in the opposite direction.

Transition Curve - A curve that contains ceaselessly changing radius. It is applied to attach a circular arc to a straight line.

Vertical Curve - A vertical curve offers a passage among two sloped roadways that facilitates a vehicle to settle the elevation rate change at a gradual rate in spite of a sharp cut.

The vertical curve is categorized as follow :- Sag Curve, Crest Curve

Also Read: Building and Road Estimating Sheet

Sag Curve - Sag curve alters the alignment of the road from uphill to downhill.

Crest Curve - It alters the alignment of the road from downhill to uphill.

Length of the circular curve is calculated with the following formula :- L = πRØ / 180

or L = Ø /360 x 2πr
or L = Ø /360 xπD

Here, L stands for the length of a circular curve.
R stands for the radius of a circular curve.
D stands for the diameter of a circular curve.
Ø stands for the central or deflection angle.

Length of the transition curve is calculated with the following formula :-
By definite rate of superelevation
Formula :- L = nh/100 (meters)
By rate of change of radial acceleration
Formula :- L = v3/aR (meters)
By arbitrary gradient
Formula :- L = hv/a (meters)

To get more details, go through the following video tutorial.

Video Source: SL Khan