Underwater rock mound

Underwater rock mound

An underwater rock mound will be constructed in Fremantle Inner Harbour to protect the Fremantle Rail Bridge from the risk of ship impact.

An underwater rock mound will be 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 will provide additional protection for the north western 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.

 

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 underwater rock mound, (clearly marked by navigational aids) will be about 60 metres long and 20 metres wide.

The highest point will be visible only in some low tidal conditions. It will not be located in the path of port vessels manoeuvring in the harbour or commercial/recreational vessels travelling through the bridge spans.

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

Barges and a tug will be used to deposit the pre-washed rocks

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

The work is expected to begin in early July and be completed in August. 

 

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