At about 0542¹ on Tuesday 22 April 2008, empty southbound manganese ore train 3DM4 derailed four wagons approximately 58 km south of Darwin near Manton Dam in the Northern Territory (NT).

There were no injuries as a result of the derailment but there was minor damage to the track and rolling stock.

The investigation found that the draft key² on the leading end of the 31st wagon had dislodged from the coupler shank, which allowed the coupler to withdraw and fall onto the track. As a result of this the train was separated into two portions; 30 wagons that were still coupled to the locomotives and the 14 following wagons which were detached. The detached portion of the train then almost certainly passed over the dislodged coupler that was lying on the tracks leading to the derailment of four wagons.

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1. The 24-hour clock is used in this report to describe the local time of day, Central Standard Time (CST).
2. Also known as 'Murray Key', the draft key is a flat steel bar that passes through the underframe, yoke and coupler. Its primary function is to secure the yoke and coupler as a unit within the underframe.

Rail safety recommendation

[RR2008-006-SR-007]