The accessibility of railway stations plays a crucial role in assessing service quality, predicting travel patterns, and developing infrastructure in the surrounding areas. This paper proposes a railway station accessibility index (RsAI) (external) that incorporates various parameters, including network performance, into a weighted measure. We reviewed different methods for measuring accessibility levels for transit systems to identify the most suitable models for this study. The primary objective of this paper is to classify railway stations into different hierarchies based on their accessibility levels and to develop an external accessibility index to measure their performance. With increasing urbanization and congestion, accessing railway stations has become more challenging, impacting railway efficiency and leading to modal shifts to other transportation systems. This paper not only identifies critical parameters but also emphasizes the need to measure and improve last-mile network performance to enhance station accessibility, thereby benefiting both passengers and the railway industry.