Updated January 2012

Road Infrastructure Damage

• Background
• Impact
• Current actions
• Local road damage

Background

December 2010 saw a monsoonal low cross the North West coast that resulted in record rainfall and extensive flooding in the Gascoyne region and adjacent areas.  The Gascoyne River peaked at 7.79 metres on the morning of 20 December; a record for the river with flood waters receding very slowly over several days.  River levels at The Wooramel River (120 km to the south of Carnarvon) and Yandoo Creek (40 km to the north) also floodreacheed their banks flood levels  with many other smaller creeks and floodways experiencing major flows.

Floodwaters caused widespread damage to homes, plantation crops, pastoral leases and livestock as well as local and state road infrastructure.

Impact

North West Coastal Highway (NWCH) received extensive damage over a 220km section extending from approximately 150 km to the south and 70 km to the north of Carnarvon, including:

• Two major washouts within 20 km south of Carnarvon – 375 m and 110 m long sections;
• 5 km of bitumen seal washed away;
• 123 km of scoured road shoulders and sealed edges (up to 2 m deep in some places);
• 5 km of earthwork embankments badly eroded; and
• damage to various off-road drains.

NWCH was closed for eight days north of Carnarvon, and 13 days south of Carnarvon, with initial reopenings kept to daylight hours only, in order to ensure a safer journey for road users.  Main Roads had major concerns that closures would impact many businesses in and around the Gascoyne region and worked tirelessly over the festive season to expedite the reopening of the Highway.

View Map of State Road Damage (1 page PDF 116 KB).

Temporary repairs to enable NWCH to be re-opened were completed shortly after the flood event allowing traffic to travel the complete highway just days before the new year.

An Alliance contract was awarded to undertake permanent reinstatement works which commenced in May 2011.  The majority of the works package was completed by October 2011 with some outstanding sealing works scheduled to be delivered by mid-2012. 

Reinstatement costs are in the order of $8m. The proclamation of this flood event as an “eligible disaster” under the Western Australia Natural Disaster Relief and Recovery Arrangements (WANDRRA) will enable a large percentage of the road repair and restoration costs to be claimed from the Commonwealth via the Australian Governments Natural Disaster Relief and Recovery Arrangements (NDRRA). 

Carnarvon’s Flood Mitigation Plan has been reviewed to incorporate the data from the December 2010 flood event. Please visit Carnarvon Flood Mitigation Works page for further information.