Operational and Statistical Assessment of Checkpoint-Induced Bottlenecks on a Selected Segment in Expressway No. 1, Iraq

Abstract Multiple reasons may cause congestion, which negatively impacts the daily lives of people. The related factors encompass high traffic demand, lack of traffic assessment, and road capacity shortage. After 2003, the congestion problem in Iraq has intensified with a daily bottleneck of segments and nodes. Hence, to tackle this problem, this research addresses one of the most congested segments of Expressway No. 1. This region has suffered from successive sectarian violence for multiple years. Though the significance of this expressway is acknowledged, there is a lack of research to assess its operational efficacy due to the presence and predicted traffic scenarios, especially with the strong influence of heavy vehicles on overall traffic performance. Both operational assessment and statistical modelling were integrated as an adopted framework to offer an extensive assessment of durability performance and efficiency in the procedure. Thus, the methodology comprises three parts, starting with the data collection. Also, Volume Balance Analysis (VBA) was conducted for traffic consistency assessment to evaluate traffic reliability and ensure the suitability of the dataset for further analysis. For the Level of Service (LOS) assessment, HCS-2010 was conducted for a base, opening, and target years to simulate and optimize the optimal resolutions. Statistical analysis was applied later as the third methodological step to evaluate the impact of heavy vehicles on traffic flow patterns. The results indicated the dataset's reliability with an acceptable imbalance rate (i.e., up to 10%) and ignored the need for any volume corrections. The analysis of LOS revealed the usefulness of lane-improved operations with a deteriorated performance from LOS D/F (2024) to LOS C–D (2034). The statistical outcomes illustrated stable flow with mean speeds ranging between 74 and 76 km/hr. Thus, heavy vehicles influenced the overall traffic stability by reducing speeds and increasing variability. The methodology illustrates that capacity improvements besides heavy vehicles impact assessment can enhance the overall operational performance and mitigate the bottleneck impact in the crucial zone of this expressway. This research offers useful insights for transport authorities to support management and planning strategies for traffic congestion mitigation.