Underwater rock mound built to protect rail bridge
An underwater rock mound has been constructed in Fremantle Inner Harbour to protect the Fremantle Rail Bridge from the risk of ship impact.

Published: 17/08/2017

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An underwater rock mound (clearly marked by navigational aids) has been built in the north-eastern corner of the Fremantle Inner Harbour to provide the rail bridge with additional protection from ship impacts.
 

The decision to install this barrier follows shipping incidents in 2011 and 2014.

The underwater rock mound is providing additional protection for the north-eastern section of the bridge.

The remaining sections are already protected by the Wongara Shoal and by structures installed in front of some of the bridge pylons by the Public Transport Authority and Main Roads WA.

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Structures have been installed in front of some of the bridge pylons by the Public Transport Authority and Main Roads WA.
 
As an added safety measure, Fremantle Ports has also invested in a ShoreTension hydraulic mooring system and installed additional storm bollards.

ShoreTension hydraulic mooring system being used on a ship
The rock mound, clearly marked by navigational aids, is about 60 metres long and 20 metres wide.
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It is not located in the path of port vessels manoeuvring in the harbour or commercial/recreational vessels travelling through the bridge spans.

Modelling undertaken shows that the impact on current flow in the main navigation channels between the rail and traffic bridges will be negligible.

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Rocks being loaded onto a barge from Victoria Quay during the construction
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Depositing the pre-washed rocks into the harbour

 

Rocks used were a minimum of 20cm in diameter and pre-washed to minimise plume during placement.

The work began in early July and was completed mid-August.