Value of rescheduling of rail inspection

A regular rail inspection schedule has been proposed to minimise any detrimental financial cost incurred due to operations under harsh environments. Missing opportunities to detect a defective rail could ultimately lead to its breaking, which would magnify the repair (as well as maintenance) cost by approximately 30–35% per rail-mile. However, the performance of a pre-planned inspection schedule may be affected by disruptions in one or more element(s) of inspection such as machine/vehicle breakdown or track unavailability, which are usually unpredictable events. As part of the justification for the need to manage a disrupted inspection schedule, this paper proposes a methodology that highlights the value of rescheduling. An extensive literature search was undertaken on the rescheduling framework in order to determine the appropriate policies, strategies and methods for rail inspection. As a result, the value of rescheduling is formulated as the ratio of rescheduling cost to a change in the value of risk from a missed opportunity to repair a defective rail, i.e. late defect detection. This numerical formula demonstrates how the proposed methodology is useful for filtering out a rescheduling strategy that has (negative) value when dealing with a disrupted rail inspection schedule. The discussion portrays several potential aspects to feasibly extend the proposed methodology on a large scale of rail network.