The relationship between traffic flow and intersection types - A case study of Ho Chi Minh city

Abstract

This study examines the relationship between traffic flow characteristics and the selection of intersection types under mixed-traffic conditions in Vietnam. Existing frameworks, such as the Lobanov's(1970) diagram, were originally developed for homogeneous automobile flows and thus fail to reflect the complex interactions of motorcycle-dominated streams. To bridge this gap, a context-sensitive Intersection Type Selection Chart was developed by integrating empirical data processing, Passenger Car Unit (PCU) conversion, and microscopic simulation in PTV VISSIM. Field data from the Hoang Dieu 2 – To Vinh Dien intersection in Thu Duc City were used to simulate three intersection types - non-signalized, signalized, and grade-separated - across multiple flow combinations. Average control delays were analyzed and classified on a two-dimensional (Nc, N0) plane to delineate operational boundaries among the three regimes. The resulting chart reveals a clear hierarchical transition: non-signalized intersections perform best at low volumes (N_c<1500 PCU/h, N₀<800 PCU/h; Signalized intersections are suitable for medium volumes (1500 ≤ N_c ≤ 2200; And grade-separated designs are necessary when both flows exceed 2200 PCU/h. Compared with Lobanov's original model, the thresholds shift to lower ranges due to the reduced effective capacity and lane discipline of mixed traffic. The developed chart provides a practical, data-driven tool for planners and engineers to guide intersection type selection in Vietnam’s rapidly urbanizing cities.