Introduction
Railway transport networks, as critical infrastructure, play a vital role in shaping spatial structures and promoting sustainable security across regions. These networks facilitate the movement of goods, services, and human capital, reduce transportation costs, enhance economic competitiveness, and generate investment opportunities—factors widely recognized in development studies and policymaking. In Iran, expanding the railway network is a central component of national development programs and holds significant potential for socio-economic advancement in underdeveloped regions such as South Khorasan.
Previous research has shown that railway development in Iran leads to lower transport costs, heightened economic competition, increased domestic and foreign investment, and improved logistics for mineral and agricultural products. Additionally, railways contribute to environmental sustainability by reducing pollution and energy consumption, a critical concern in the context of global climate change. From a security perspective, railways facilitate military logistics, strengthen border security, and mitigate the impact of transport disruptions, thereby supporting sustainable regional security.
Despite extensive studies on the economic and spatial impacts of railway networks at national and regional scales—mostly through econometric analyses—their direct role in political spatial development and sustainable security remains underexplored. This study addresses this gap by examining the impacts of railway infrastructure on the economic, political, and security dimensions of South Khorasan, a peripheral border province. Using a mixed descriptive-analytical and survey-based methodology, the research provides novel insights into the broader socio-political effects of railway development, enriching existing knowledge and informing region-specific strategies.
 
Methodology
This descriptive-analytical study employed a researcher-designed questionnaire consisting of 45 items, divided into two domains: economic development (24 items) and sustainable security (21 items). Responses were measured on a five-point Likert scale ranging from very low to very high. Content validity was ensured through expert review, while reliability was confirmed via a pilot test, with Cronbach’s alpha coefficients exceeding 0.9. The study sample included 270 economic actors and domain experts associated with the provincial railway network. Data were analyzed using SPSS, applying non-parametric binomial tests and t-tests for inferential statistics.
 
Findings
The results demonstrate that improved railway access significantly enhances investment attraction, mine revitalization, border market development, and transportation cost reduction (Table 5). Inferential analyses confirm that the railway network’s economic impact on the province is well above average (M = 4.06, p < 0.001). In terms of sustainable security, the railway contributes substantially to strengthening border security, facilitating military logistics, and reinforcing regional security, with statistically significant effects (M = 3.86, p < 0.001). Friedman test results further highlight border market activation and mine revitalization as the most influential economic impacts, while food security sustainability and the neutralization of transport strikes emerge as key outcomes in the security domain.
 
Discussion and Conclusion
The findings confirm that railway network development exerts a strong positive influence on Southern Khorasan’s economic, political, and security landscape. As critical infrastructure, the railway fosters investment, employment generation, border security, and social stability, while also mitigating center–periphery disparities. By reducing the province’s geopolitical isolation and enhancing governance indicators, the railway acts as a catalyst for broader national cohesion.
Through a mixed-methods approach in a less-developed regional context, this study provides a comprehensive perspective on the multifaceted effects of transport infrastructure, extending beyond economic growth to encompass political and security dimensions. Nevertheless, limitations such as the single-province focus suggest the need for future research across broader geographic and methodological scopes to strengthen generalizability. Policymakers are advised to incorporate political and security considerations into railway development planning to maximize long-term benefits.