Details about curve widening of a road

This civil engineering video tutorial is based on curve widening or pavement widening of a road.

It is noticed that the breadth of pavement and a horizontal curve is retained in excess of the normal breadth of pavement. This method for widening the pavement is called curve widening.

The curve widening plays an important role for creating highway metric design.

The widening of pavement and horizontal curve is done for the following reasons :-

At the starting point of the curve, the drivers generally prefer to follow the exterior edge of the pavement to get better view and more sight distance which require additional width of the road.

If it is found that the vehicle contains a rigid wheel base and it is possible to only turn the front wheels, when the vehicles have turn on horizontal curve, the back wheels fail to follow the similar path as compared to front wheels.

For this purpose, it is necessary to arrange additional widening.

Often, in excess of design speed, the back wheels slip externally and cover more width of road and for this reason, additional width is required.

To determine, how much extra pavement width should be provided on a horizontal curve, the following formula is used :-

Also Read: How to measure different types of curves in roads

Total Widening Of Pavement = Widening because of psychological effect + Widening because of mechanical effect

Total Widening Of Pavement = Ws + Wm. W = V / 9.5√R + nL2 / 2R

Here, W denotes total pavement widening.

R denotes radius of curve in meters.

V denotes design speed of vehicle in KM / Hrs.

N denotes number of traffic lanes.

L denotes length of wheelbase of longest vehicle in meters.

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

Video Source: SL Khan