Modeling Traffic Parameters Accounting for Platoon Characteristics on Multilane Highways

Most vehicles on highways experience platoon congestion, primarily due to the impedance created by heavy vehicles (HVs). The platoon generated by the HVs directly impacts the smooth traffic flow conditions, affecting the travel time, speed, capacity, and level of service. The study aims to model and analyze the impact of HVs considering the platoon characteristics observed on Indian highways. A significant amount of traffic data, such as volume, speed, and time headway, was collected from highway sections using infra-red sensors. The average coefficient of variation of speed criteria was used as an indicator of variability (IoV) to estimate the critical time headway. The threshold value of critical time headway of 3 s was identified for classifying vehicles into non-platoon followers and platoon followers. The traffic speeds were modeled using the simultaneous equation approach. The speed-flow-density curves were developed for the two traffic regimes. The platoon regime results indicate that the percentage reduction in the speed at capacity, density at capacity, and traffic capacity was 10.8%, 13.5%, and 22.9%, respectively. Further, it was identified that the travel time at capacity increased by 10.6 s/Km under platoon conditions compared to non-platoon conditions. Consequently, the travel delay at capacity increased by 12.2%. The study shows that the traffic interaction under platooning conditions predominantly affects the traffic operational quality (level of service) and efficiency. The research findings emphasize the significance of considering the platoon dynamics under the influence of HVs to explain their impact on the macroscopic traffic flow characteristics.