The reliability assessment of the railway services is a complex procedure that is affected by many different factors. A railway system is reliable when the trains arrive at their destination within the allowed delay threshold. The objective of this study is to investigate the effect of the infrastructure doubling and electrification on the reliability of the train schedules. In this study, advanced event-driven stochastic simulation software is developed to determine the reliability of the train movements. The calculation of the average train delay as a benchmark is provided to evaluate performance. We compared average train delay with the acceptable delay to define a new benchmark to determine the reliability of the train movements. We also analyzed the delay cascading effect along the railway line in order to better illustration of a number of correlations between the arrival and departure delays at different stations. The model has been validated through a real-world case study of Iranian railway. Successful validation of the developed simulation system demonstrated that the model provides accurate reliability estimations in both congested and non-congested situations. Furthermore, the experimental results showed that electrification and doubling improve the reliability significantly.