Service life prediction of worn contact wires under multiple failure modes

Contact wires are critical components of railway overhead infrastructure which provide power for trains. This paper proposes an innovative method to determine the service life of worn contact wires under three failure modes: tension, fatigue, and attrition. The tensile stress, fatigue damage, and cross-section loss of contact wire have been modelled as stochastic processes following lognormal distribution. The first-passage probability method is then used to determine the time-dependent failure probability for contact wires under each failure mode. The service life of the contact wire is determined through system reliability analysis. This method has then been applied to a case study to provide information on behaviour evaluation of contact wire. It has been found that the service life of contact wire can be underestimated without considering the wear effect on fatigue failure mode. Also, through sensitive analysis, it has been determined that the wear rate of contact wire can affect the probability of fatigue failure considerably in the longer term. The methodology proposed in this paper can help engineers and asset managers in making optimum decisions regarding the time of repair and/or maintenance of contact wire exposed to wear.