Life-time management of rails based on structural reliability approach

Abstract

Preventing derailment due to broken rails is an area of high priority for keeping a safe rail industry. The common method to control the risk of rail breaking is a frequent rail inspection through nondestructive testing technologies and a replacement of rails based on the remedial action plans. However, determining the effective (optimal) inspection frequency is not an easy task and setting exact inspection intervals requires critical decisions in railway infrastructure management.

In this research paper, the rail model is developed using ABAQUS/CAE and FRANC3D software and fracture mechanics is used for the determination of critical crack -size at a rail head, web and base as well as fatigue life of rail. First order reliability analysis is carried out and reliability of rail as well as a mechanism of remedial action is recommended to help an infrastructure manager’s decision. Eventtree analysis and life cycle cost estimation is also conducted.

Based on the analysis results, an annual, uniform and effective rail inspection frequency is assessed with 99.5% rail reliability for the applied stress and tonnage using non-destructive technologies which result in minimal total cost. Finally, critical cracks of rail before failure are determined as1mm for rail head, 5 mm for the rail web and 2 mm for the rail base to help infrastructure managers’ (track engineers or rail inspectors) decision for replacement.

Keywords: Rail Inspection, Reliability Index, ABAQUS/FRANC3D, Fracture Mechanics and Life-Cycle Cost