<span class="" id="parent-fieldname-description"> An investigation into the partial separation of an express passenger train has led to the ongoing replacement of tail pins on RailCorpâs express passenger trains. </span> <p>The Australian Transport Safety Bureau alerted RailCorp to the potential issue during an investigation initiated in August 2011, when a Melbourne-Sydney express passenger train partially separated as it passed over a dip in the track near Broadmeadows, Victoria, according to the bureau.</p><p>“The train suffered a total loss of power and was unable to continue its journey, coasting for a short distance,” the ATSB described.</p><p>“Initial inspection of the train suggested that the electrical disconnection was a result of the leading power car decoupling from the carriages but it was clear that the power car and carriages stayed close together because the brake lines remained connected.”</p><p>What had happened, in fact, was that an element of the draft gear (the assembly connecting the train’s cars) had failed.</p><p>The element in question was a 590mm steel tail pin, which had broken as a result of an overstress fracture.</p><p>The fracture, the ATSB said, “was caused by fatigue cracking – cracking that, worryingly, recent routine ultrasonic testing had not detected.”</p><p>“Post-incident material testing established that the mechanical properties of the tail pin were below the required standard,” the bureau told.</p><p>While this type of fault is unlikely to result in a derailment, the ATSB explained, “the consequences of such an event involving a passenger train, should it occur at speed, were potentially very significant.”</p><p>Following the initial incident in 2011, the ultrasonic testing procedure was revised to improve the detection of smaller cracks in the tail pins of express passenger trains, but the separation of another such train near Seymour, Victoria in August 2012 showed that the ultrasonic testing regime was still not detecting all fatigue cracks, the ATSB said.</p><p>In response to an ATSB notice days after the second incident, RailCorp set about developing a new testing process and fitting newly designed tail pins.</p><p>“As a result of the investigation, a new batch of tail pins has been manufactured to an upgraded standard which includes improved quality control and acceptance testing and RailCorp is currently in the process of fitting these new tail pins,” the ATSB said.</p>
