Lateral placement of U-turns at median openings on six-lane divided urban roads

Abstract

Study on lateral placement of U-turning vehicle is carried out by collecting data at 13 different median openings of six-lane divided roads. It was found that the lateral placement of “all the vehicles” taking U-turn at median opening may be unimodal or bimodal. The unimodal distribution was described by normal distribution, whereas bimodal distribution was described separately by two different normal distributions; one for “only 2-W” and other for “all the vehicles excluding 2-W.” Equations were developed and parameters were calculated to describe a bimodal placement distribution curve. The issue of bimodality in placement was investigated statistically and the separation factor (S(r)) and placement factor (PF) were used to describe the issue. This study on the lateral placement of U-turning vehicles holds significance in the better estimation of conflicting traffic volume, which is essential for the correct estimation of the capacity of U-turns at median openings in mixed traffic condition.