Railways, as one of the main urban infrastructures, have played a significant role in transforming urban transportation systems. Despite their economic, environmental, and safety advantages, railway corridors in some cities have caused spatial fragmentation and physical separation within urban fabrics. The passage of railway lines through built-up areas has led to declining land values, the emergence of unsafe spaces, reduced spatial accessibility, and environmental problems. District 16 of Tehran, which hosts the Tehran–Mashhad railway corridor, represents a clear example of these challenges. Accordingly, the main research question of this study is to identify the spatial conflicts arising from the adjacency of railway corridors and urban fabrics and to explain an appropriate approach for their coexistence. The study adopts a qualitative research approach using a case study method. Data were collected through documentary and library studies, field surveys, and interviews with relevant actors. Reviewing laws and regulations, examining international experiences, and identifying challenges within the study area guided the research framework toward a city–rail coexistence approach. The findings indicate that responses to city–rail adjacency range from radical and passive approaches, such as relocating or burying railway lines, to more realistic approaches emphasizing coexistence and positive interaction. The city–rail coexistence approach, by moderating functional conflicts of railway corridors within urban fabrics, facilitates spatial integration between the city and the rail system. Finally, key requirements for organizing and reducing adjacency-related problems in the study area are presented.