Derailment of Train 5PS6, Bates, South Australia, on 19 April 2008

Executive summary

At approximately 0650 on 19 April 2008, freight train 5PS6, travelling from Perth to Sydney, derailed near Bates, SA. The derailment occurred about 13 track kilometres east of Bates. Thirteen wagons were derailed and about 800 m of track was damaged. There were no injuries.

The investigation concluded that an undetected crack at an unused bolt-hole increased in size until the rail completely fractured. The rail probably failed under the previous train (5MP5). As the wheels of train 5PS6 passed over the fracture, the impact forces caused the progressive failure of sleepers, a secondary rail fracture and the ejection of a small section of rail. Once a section of rail was missing, the impact forces on the rail increased significantly, causing the progressive failure of rail and sleepers until the freight wagons inevitably derailed.

The investigation acknowledged that new maintenance procedures were issued to reduce the risks related to bolt-hole cracks. However, the Australian Transport Safety Bureau has issued two safety advisory notices, concluding that there were further opportunities for improvement relating to:

• additional development of the ultrasonic testing process aimed at reducing operator dependence
• the relationship between heat-affected metal and stress concentration when specifying how far a bolt-hole should be from the rail ends before welding.