Advancing Sustainable Urban Transport by Investigating Traffic Heterogeneity

Rapid daily changes in global economic dynamics have become a major driver of widespread urbanization worldwide. Urban populations in all countries are experiencing significant growth, and this expansion of heterogeneous traffic, along with a lack of lane discipline in urban areas, is putting a strain on transport infrastructure. The need to address urban traffic flow in these growing cities is critical, emphasizing the importance of improving public transport infrastructure. This study investigates traffic heterogeneity by estimating Dynamic Passenger Car Units (DPCUs), analyzing urban traffic characteristics, and developing free-flow speed models. The Speed-Area Ratio Method was employed to calculate DPCUs for various vehicle classes, with the standard car as the reference. These DPCU values were compared against Indo-HCM (2017) norms, revealing notable deviations, particularly for vehicles such as SUVs with significantly higher free-flow speeds. The findings demonstrate that free-flow speeds improve linearly with carriageway width, while median gaps inversely affect traffic flow. SUVs dominated free-flow traffic, followed by small cars and sedans, while buses maintained consistent speeds during non-free-flow hours. The developed free-flow speed models, with R2 values of 0.5909 and 0.5910, indicate that the fifteen-minute intervals used in the analysis had minimal impact on overall speed. However, the divergence of calculated DPCU values from Indo-HCM (2017) underscores the necessity of revisiting these standards to reflect the dynamic traffic conditions of Indian cities more accurately.