Study on impact of Gradient on capacity of two Lane Undivided National Highways

Abstract

In India the major part of highways are falls under two lane undivided category. These lanes attains its greatest limits very soon and hence requires periodic upgradation, to do it is required to estimate capacity on selected roads. For determining the capacity it is important to study the behaviour of traffic flow. There are various factors which affect the capacity are geometry of roadway, behaviour of driver, traffic and environmental conditions.

The main objective of the present study is to know the effect of roadway geometry such as gradients on the Passenger car units of vehicles, and capacity of the selected stretches on the different national highways.Data has been collected at 12 different sites of NH-207 and NH-209 using both manual and videography technique for a period of 12 hours.

It is observed that PCU values are decreasing with the increase in gradient, since the speed ratio is directly proportional to the PCU values also developed linear regression equation to estimate the capacity of two lane highways under varying gradients and found capacity of the lane reduces as the gradient increases.