Traffic Performance Analysis of Uncontrolled Intersections under Heterogeneous Traffic Mix

Abstract

The traffic flow in an urban environment of the sub-continent region varies significantly from that of the western world. Such a traffic flow is characterized by heterogeneity having an amalgam of slow and fast-moving vehicles, aggressive drivers’ behavior, lack of lane discipline, and noncompliance to the priority rule. Most of the intersections operate under uncontrolled (devoid of stop/yield sign and signalization) conditions. Several studies have been conducted around the globe to investigate traffic performance at intersections where traffic flow is homogeneous and lane discipline is followed however, the literature on uncontrolled intersections with heterogeneous traffic conditions is rather limited. The developed models are not completely analogous to heterogeneous conditions and yield erroneous results. This study attempts to analyze traffic performance (operational and safety) and provide a simplified and systematic approach to estimate different traffic performance measures at uncontrolled intersections for traffic operating in an urban environment under heterogeneous traffic mix. It presents a case study of an urban uncontrolled T-intersection located in the city of Multan, Pakistan. The videography technique is used to obtain traffic data and extract basic traffic parameters. Traffic operational performance measures such as level of service, queue length, travel time delay, critical gap, and the number of conflicts for safety analysis are estimated. Simulation technique is also introduced to estimate surrogate safety measures such as post-encroachment time (PET) and time-to-collision (TA) to determine conflict severity. In the end, a scenario (signalization) is considered to determine whether the intersection understudy would experience improved traffic performance if traffic signal control is introduced at the intersection. The present effort aims to serve as a guide to practicing traffic engineers to analyze traffic operational and safety performance at uncontrolled intersections where traffic conditions are mixed, and rules of priority are not strictly observed.