Urban Railway Operation Plan Subject to Disruption

The life cycle of an urban railway system is about thirty years, and therefore, any small improvement in operation, results huge savings. The daily operation follows a headway distribution, which itself computed based on the traffic volume. Passing the block sections and stopping in stations are always contaminated with disruptions. The disruptions affect the traffic especially when the headway is in minimum. In this paper, computing the exact practical travel and dwell times is studied. At the first stage a formula is proposed to compute the remained disruptions at the end of the last period in minimum headway. It is supposed that the travel and dwell times take values according to a symmetric distribution. The amount of supplementary times to reach the desired reliability is defined based on the probability of non-absorbed disruptions at the end of the last period. It is concluded that as the number of disrupted travel and dwell times increases the amount of required supplementary times to reach the same level of reliability, increases but in a descending rate. This finding improves the current method to reach the reliability in urban railway operation plans. Finally, the Karaj Metro Line 2 is studied and analyzed as the case study.