A COMPOSITIONAL APPROACH FOR TRAFFIC DISTRIBUTION EVALUATION OF TRIPLE LEFT-TURN LANES FROM AN INDIVIDUAL PERSPECTIVE

Li Li,Gui-Ping Wang,Ping Wang,Dong Zhang,Xiao-Yun Cheng

doi:10.3846/transport.2021.14676

Abstract

This study analysed unbalanced traffic distribution on Triple Left-Turn Lanes (TLTLs) at signalized intersections that is caused by left-turn drivers’ unequal lane preferences. To develop statistical bonding between the multilane traffic flow and individual lane choices, the lane volumes are formatted as compositional data to subject the sum-constant constraint. One-way and two-way Compositional ANalysis Of VAriance (CANOVA) models were formulated respectively to estimate the independent effect of one factor and its joint effects with other factors on the multilane traffic distribution. TLTL volume composition was the dependent variable of the models, while the factors of geometric design and traffic control that could affect left-turn drivers’ lane choice were the independent variables. Results indicate that variance of vehicle turning curve, length of the upstream segment, the location of triple left-turn sign, signal phase / cycle length, could affect the traffic distribution, and its balance could be achieved at specific levels of a factor. The joint effects of some factor couples could improve the unbalanced traffic distribution while others could not work.

Highlights

Turning vehicles merge as one traffic movement or diverge to different destinations at signalized intersections
From the estimated independent effect of signal cycle length F0 on traffic distribution on the Triple Left-Turn Lanes (TLTLs), we find that the increase of cycle length could decrease the average volume ratio of the inside LTL with respect to the whole leftturn traffic, while raising the one of the medians or the outside LTL
From the estimated independent effect of the distance of the TLTLs to its first sign at upstream F3, we find that the unbalanced traffic distribution on the TLTLs could be improved in the red phase or entire cycle time by setting the sign or marking close to the upstream intersection

Summary

Introduction

Turning vehicles merge as one traffic movement or diverge to different destinations at signalized intersections. The traffic with the heavier demand is allocated to more lanes. The capacity of these multiple lanes serving the same traffic is directly related to the saturation flow rate of each lane, so most studies of multilane operation concerned about how to maximize the rate (Bagheri et al 2015; Chen et al 2011; Cooner et al 2011; Yi et al 2012; Zhao et al 2017). Compared with the variation of lane saturation flow rates, another reason of multilane capacity reduction, multilane underutilization, has attracted much less attention previously, which is the main concern of this study

Methods

Findings

Discussion

Conclusion