Assessment of Geometric Enhancements at Intersections on National Highway Using Microsimulation Approach

The performance of transportation networks depends on efficient and safe traffic management and control at the crossings located on National Highways (NH). At these crossroads, travelers are likely to experience higher delays, traffic congestion, and vehicular emissions. The present study evaluates vehicular emission levels at NH crossings under prevailing heterogeneous traffic conditions using the available emission modeling tools such as the microsimulation technique. The research also evaluates the effect of traffic movement restrictions and applies designed traffic control in addition to geometric enhancements to improve traffic operations, and hence reduce emissions significantly. The PTV-VISSIM microsimulation tools were used to simulate traffic at selected intersections. Model calibration and validation using spot speeds, traffic volume counts, and continuous unmanned aerial vehicle (UAV) video data for a selected duration. The Wiedemann-74 car-following model was calibrated to correctly mimic the varying traffic conditions. As one of the important outcomes, the authors assessed the solutions' efficacy of proposed geometric interventions, including traffic operations and control. It was found that Intersections with an existing Level-of-service (LOS-F) imply heavy congestion in the case of a business-as-usual scenario. Additionally, using a validated simulation model, it was also found that the suggested improvements reduce the delays significantly, improving the LOS-F to LOS-C. Further, with an assumed growth rate of 6%, it is established that the achieved LOS-C (using proposed interventions) is likely to be sustained through for a substantial number of years before it could deteriorate to LOS-E till 2031. Further, emission modeling revealed that there could be a reduction by 50–70% in CO emissions due to proposed interventions. This considerable drop indicates the proposed measures' additional benefits in terms of improving traffic operations as well as vehicular emission levels. The study demonstrates the approach of evaluating the suggested improvements related to roadway geometry and traffic control prior to its real-life implementation.