The rail system's capacity serves as a gauge for the calibre of train operation. There are numerous techniques to improve the capacity of Railway trains serving airports. The ability to choose the strategy that will cost them the least money is crucial for decision makers and infrastructure managers to possess at their disposal. This decision-making process can be complicated at times, and how to improve capacity is a crucial choice that will have a big financial impact. In this article, we discuss the key ideas and procedures for carrying out line capacity studies. The study would include suggestions for improving line capacity. The two objectives of this study were to analyse a critical block that specifies the lowest possible time headway and the variables affecting line capacity. The study demonstrates how capacity varies in response to elements including train speed, stability, train heterogeneity, train number, and the separation between railway signals.it concluded that the speed variance between the two trains had a direct impact on the minimum headway. The headway also increased as the speed differential did. whereas impacted by block length, it has an inverse relationship. The block length increases, but the time headway decreases.