Given the capacity constraints of the rail network and its operational competition with the road network, identifying critical block-sections and assessing the rail network’s vulnerability, to eva‎luate the consequences of reduced block-section capacity, is considered one of the important issues in the field of transportation. eva‎luating the consequences of disruptions in the rail network and identifying critical block-sections helps decision-makers optimize budget allocation, maintain freight and passenger flows in the green rail mode, and reduce economic and environmental costs. In this study, the vulnerability assessment of the rail network and the identification of critical block-sections, considering the capacity constraints of block-sections and the competition between rail and road transportation modes, are presented through the development of a two-phase methodology. In the first phase of the proposed methodology, under non-disruptive conditions and using all-or-nothing traffic assignment models and capacity-based incremental assignment, the block-sections of the rail network are divided into four categories. In the second phase of the proposed methodology, disruptions are introduced in block-sections with a volume-to-capacity ratio exceeds unity, and the flow is reassigned to the rail network. Finally, using internal and external cost indices and freight and passenger flows, the identification and ranking of the rail network’s critical block-sections are conducted. Additionally, based on the proposed methodology, a vulnerability analysis of Iran’s national rail network (as a case study) is conducted using demand and capacity data for the horizon year 1414 (2035). The results indicate that, contrary to intuitive expectations, the bottleneck block-sections of the rail network under normal conditions are not necessarily the most vulnerable block-sections. The results also show that vulnerable block-sections in the normal conditions of the rail network carry significant flow, a statement that aligns with existing research findings in the literature on network vulnerability. The results of this study can be used as an effective and efficient tool for policymakers and managers to prioritize critical block-sections and infrastructure projects in the rail network.

محمد تمنايي

حسين حق شناس , احمدرضا جعفريان مقدم