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Risk-based scheduling methodology for audit inspections of curves on high-speed mainline tracks

Agencies with safety oversight responsibilities of railroad tracks often perform walking audit inspections of tracks (also referred to as quality audits) to complement and oversee the regular inspections performed by the railway operator or maintenance manager. Traditionally, these audit inspections are scheduled based on the qualitative evaluation of the rail line by the inspectors, together with the available schedule of the inspector(s). This paper presents an approach to replace the current qualitative decision-making process for determining when and where to conduct audit inspections with a quantitative decision-making process. This quantitative process first establishes an acceptable level of risk in a given territory, and then taking into account the defect history and real-time track conditions, it schedules audit inspections based on those conditions. This risk-based scheduling methodology of audit inspections can be used by the safety oversight agencies and inspectors to monitor and “spot” check track conditions and provide oversight over the normal inspection process. The audit inspection’s frequency algorithm, presented in this paper, establishes the acceptable level of risk based on six years of Federal Railway Administration safety audit inspections data of the Amtrak North East Corridor. This methodology takes into account the track conditions in terms of the curve defect rate and optimizes the scheduling of audit inspections of mainline curves based on this defect condition. The risk-based curve audit inspections interval methodology outputs the required maximum curve audit inspections interval (time until next audit inspection or reinspection) while maintaining an accepted level of risk in the presence of real-time curve defect rates.