Purpose: The circular economy has emerged as a new paradigm in sustainable development and has attracted significant attention from management scholars and practitioners. Today, many academic institutions and manufacturing companies are striving to understand this innovative approach and intensify their efforts to localize its requirements. To identify the circular economy, it is first necessary to determine its influencing factors and then customize these factors according to the characteristics of each industry. The Iranian rail transportation industry possesses substantial potential for circular production; therefore, this study investigates and localizes the factors influencing the circular economy within this sector. Accordingly, the main objective of this research is to identify the factors affecting the circular economy in the rail transportation industry.

Methodology: This study is applied in terms of purpose and seeks to describe the factors influencing the circular economy in the rail transportation industry. From a methodological perspective, it adopts a quantitative approach and is classified as a cross-sectional study. The research domain encompasses the Iranian rail transportation industry. Data were collected through a field study using a spherical fuzzy checklist as the data collection instrument. The research was conducted in two stages and several steps. In the first stage, a literature review and brainstorming sessions were employed to extract the factors affecting the circular economy. In the second stage, the Spherical Fuzzy Delphi technique was utilized to validate and accept the identified factors within the rail transportation industry.

Findings: In the first stage, 42 factors influencing the circular economy were identified through literature review and expert interviews. Among these, 39 factors were extracted from the literature, while 3 additional factors were identified through brainstorming and expert consultations. In the second stage, the Spherical Fuzzy Delphi method was employed to screen and evaluate the factors, resulting in the localization of 30 key factors influencing the circular economy in the rail transportation industry. A second round of the Spherical Fuzzy Delphi process was also conducted, demonstrating convergence between the two Delphi iterations. The results revealed that human resource capacity, circular economy benefits, and financial and economic support were the most influential factors affecting the circular economy. Furthermore, value-added product design and production, technology and infrastructure, renewable resource development, and the capacity of the rail transportation industry were found to have substantial impacts on the implementation of circular economy practices. Given their critical importance, these factors play a vital role in the industrial circular economy approach within the rail transportation sector and should be considered high-priority areas for implementation.

Conclusion: The factors affecting the circular economy can be categorized into six dimensions: production, managerial, economic, political, social, and environmental. The findings indicate that 11 factors belong to the production dimension, 4 to the managerial dimension, 2 to the economic dimension, 6 to the social dimension, 2 to the political dimension, and 5 to the environmental dimension. Among these, the production dimension accounts for the largest share, highlighting its central importance in the circular economy approach. From an innovation perspective, this study contributes to the literature by evaluating circular economy factors through the novel Spherical Fuzzy approach and localizing them for the Iranian rail transportation industry. The main contribution of this study lies in employing the Spherical Fuzzy Delphi approach to systematically screen and localize circular economy factors for the rail transportation industry. Furthermore, compared with previous studies, this research provides a more comprehensive identification of influencing factors and addresses an important practical gap in the localization of circular economy implementation within the Iranian rail transportation sector.