Gradient of Road

-It is defined as the rate of rising or falls along the length of the road w.r.t the horizontal.

-It is expressed as a ratio of 1 in x (1 vertical unit to x horizontal units).

-It is sometimes also expressed as a percentage, n (i.e. n is 100).

Factors affecting gradient

-Characteristic of the traffic.

-Design speed.

-Physical features of the site.

Types of Gradient

-Ruling gradient.

-Limiting gradient.

-Exceptional gradient.

-Minimum gradient.

Ruling Gradient:

Ruling gradient is the maximum gradient within which the designer attempts to design the vertical profile of a toad.

Gradients up to the ruling gradient are adopted as a normal course in the design of vertical alignment and thus the quantities of cut and fill are balanced. Hence ruling gradient is also known as the design gradient.

Limiting Gradient:

Whenever the topography of a place has steeper gradients, then we provide limiting gradient which is more the ruling gradient.

But the length of limiting gradient is limited considering the safety.

Exceptional Gradient:

In some cases it may be unavoidable to provide a steeper gradient at least for short structures and in such cases, an exceptional gradient may be provided. Exceptional gradient should be strictly limited only for short stretches should not exceed about 100 m at a stretch.