Value of rail inspection reschedules

A regular rail inspection schedule has been proposed to minimise any detrimental financial cost incurred due to operations under harsh environments. Missed opportunities to detect a defective rail could lead ultimately to it 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 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 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 large scale of rail network.