The influence of vehicle type composition on heterogeneous traffic flow

¹ The University of Electro-Communications, Japan
² The University of Tokyo, Japan
³ Beijing University of Technology, China

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Published online: 12 September 2025

Abstract

To better understand heterogeneous trafic with weak lane discipline (2D mixed trafic), it is essential to investigate the effects of vehicle type composition (e.g., motorcycles, cars) on trafic characteristics. Using actual trafic data collected in Mumbai, India, this study examines the macroscopic characteristics of trafic with various proportions of different vehicle types, employing fundamental diagrams (FDs) based on passenger car unit (PCU) values. Three different PCU methods were used to ensure the consistency of the results. The findings reveal that for all vehicle types, an increase in the proportion of any specific vehicle type corresponds to a higher trafic volume in the free-flow phase. This tendency remains consistent even when using other PCU methods, demonstrating the robustness of the results. These findings suggest that unbalanced distributions in the proportions of vehicle type enhance trafic capacity.