Analysis of Traffic Flow Characteristics Based on Area-Occupancy Concept on Urban Arterial Roads Under Heterogeneous Traffic Scenario—A Case Study of Tiruchirappalli City

In developing nations such as India, the urban arterial roads carry various vehicles that follow weak lane discipline. During peak hours of traffic, the degree of heterogeneity is so high that it leads to improper utilization of the roadway facility, thereby affecting the functional and operational characteristics of the traffic stream. This paper proposes to analyse the traffic flow characteristics of the urban arterial road stretches with heterogeneous traffic conditions in Tiruchirappalli city, India, using the macroscopic fundamental diagrams (MFDs). The three essential traffic variables include speed–flow–area-occupancy on one side and speed–flow–density on the other side. This paper gives a systematic general idea to analyse the heterogeneous traffic considering the area-occupancy as a concentration performance measure instead of the conventionally followed density concept. The MFDs are established using the speed–flow–area-occupancy and speed–flow–density, and a comparison was made between them for bidirectional traffic. The study shows that the traffic stream characteristics analysed using the speed–flow–area-occupancy method give reliable and consistent results with the highest values of goodness-of-fit parameter coefficient of determination (R²) when compared to the speed–flow–density method. As a result, using area-occupancy as a performance measure, one can quantify changes in traffic characteristics in terms of vehicular interactions. The study results may be useful to researchers, traffic engineers, and practitioners for developing macroscopic capacity models for urban arterial roads under heterogeneous traffic conditions.