Single-track line railway operations are complex due to their reliance on crossings, where trains must pass at specific locations within constrained time windows. Capacity utilisation can be assessed using different methods, but variations in how crossings and operational dependencies are accounted for may lead to differing results. This study analyses the impact of including crossing stations in capacity utilisation assessments and examines the effect of enhanced interlocking functionality, specifically simultaneous entry. Through a case study, we explore how different methods account for crossing station operations and thus influence capacity estimates. The results highlight the importance of infrastructure design and properly accounting for crossing station aspects, as well as the marginal benefits of simultaneous entry depending on the timetable. These insights contribute to an improved single-track line capacity analysis, leading to more informed railway planning and investment decisions.