There is a growing acceptance of and interest in transit accessibility-based developments as a means to address urban challenges, such as automobile dependency, air pollution, urban sprawl, and congestion. Additionally, prompting car drivers to switch to public transit requires the construction of attractive and accessible public transit systems. Accordingly, it is necessary to measure railway network performance while considering accessibility, which indicates the potential opportunity of interaction. Thus, this study aims to develop a railway network performance index (RPI) to evaluate transit accessibility, with regard to differences in travel speed, and conduct a comparative analysis of 40 cities worldwide. The major findings are as follows. European cities have a high RPI, but cities in developing countries have relatively low RPI values, due to railway infrastructure shortages. Railway and station density have a positive relationship with RPI, but differences in RPI emerge between cities with the same infrastructure levels. This difference indicates the importance of efficient railway system connections between the distributions of populations and facilities. Overall, this study enhances understandings of transit accessibility and provides benchmark points that may be useful for decision-making processes, transportation investments, and land use policies.