Reschedule or not? Use of benefit-cost indicator for railway track inspection

Effective planning of railway track inspection utilises characteristics of a track condition deg-radation model. When a statistical approach is adopted for track degradation modelling, prior knowledge about uncertainty of model parameters normally receives an update when new inspection data arrive. The model updating can suggest a new inspection schedule and/or with additional inspection(s) in some parts of the existing schedule. However, the suggestions to improve inspection schedule effectiveness might not work unless the rescheduling plan can be economically justified (i.e. the benefit-cost ratio remains greater than 1). Thus, this study proposes an indicator, this is, signifying whether a plan to reschedule the affected part of the inspection schedule should be carried out or not. To achieve the goal of this study, we modify the benefit-cost model of track preventive maintenance. As a result, the indicator which takes the probability of defect detec-tion and an absolute deviation between the likelihood of a sudden shift and the ratio of two maintenance costs into account is formulated. Two disruption scenarios of track inspection schedule are considered in this study to demonstrate how the proposed indicator can be utilised in practice.