Capacity Analysis Of Roundabouts

1869 Words4 Pages

Capacity is the main determinant of analysing the traffic performance of roundabouts. The movements of the vehicles were observed at 2 roundabouts in Varanasi. Gap acceptance and follow up time were estimated for cars for one hour analysis. The relation between a roundabout performance measure and capacity is expressed in terms of degree of saturation (volume – Capacity ratio). The capacity analysis is done based on gap acceptance method that is adopted by Tanner based on the HCM 2010. The traffic movement data with vehicle characteristics were collected from 2 roundabouts in Varanasi. These 2 roundabouts are directly related to their approach leg numbers.Approach entry capacity has been analysed for all 2 roundabouts at their legs. Effective capacity verses entry flow relationship have been developed in order to find out the causes of their over Saturation (v/c ratio greater than 0.85) And the result indicates; number of entry lanes, number of circulatory lanes and high traffic flow are the major causes of their over saturation.
Key words: Roundabouts, capacity, vehicles.

Introduction

A roundabout is an alternative form of intersection traffic control. Roundabouts are generally circular in shape, characterized by yield on entry and circulation around a central island. Roundabouts …show more content…

It is also mentioned that the left lane will be served at a faster rate than the right lane and because of this travel time minimization would be a better predictor. Akcelik’s use of dominant and subdominant lanes .so this is problem from a different angle. Fisk and Akcelik both recommend using a different critical gap and follow uptime for each lane. In Akcelik’s model lane utilization ratio is determined by the degrees of saturation of the lanes. Lane group capacity is then calculated and flow rate for each lane is

Open Document