A freak storm caused a cargo ship to break lines and smash into Fremantle Rail Bridge in the space of eight minutes, a preliminary report by the Australian Transport Safety Bureau shows.
On August 17 a bollard that was holding all three of the AAL Fremantle's stern lines and two from the car carrier the Grand Pioneer ripped off a wharf at Fremantle Port, causing both ships to swing away from berth.
The AAL Fremantle hit the bridge, causing damage to the structure and railway tracks and resulting in two weeks of disruption to train services.
According to the report, a weather warning had been issued earlier that day and Fremantle Ports had notified both ship masters to take precautions.
But a thunderstorm which struck at 11 pm generated winds reaching 101km/h within a few minutes.
Investigations continue into why the bollard failed and the preparedness of the ships at the time.
The final report will be available in August 2015.
