Motorists in Perth's southern suburbs can expect an early Christmas present, with the Armadale Road dual carriageway anticipated to be open by 20 December.
The $145 million project, started in March 2018, has converted the previous four-way signalled intersection into a four-lane bridge over Nicholson Road, with a roundabout underneath.
It was fast-tracked under the $2.3 billion "Boosting Jobs, Busting Congestion" infrastructure package announced by the State and Federal Government in 2017.
On December 20, two lanes of Armadale Road in each direction from Tapper Road to Anstey Road are expected to be open, along with one lane each way over the Hugo Throssell VC Bridge.
Nicholson Road will be reopened, under traffic management, with one lane in each direction.
The entire project, including landscaping and the Principal Shared Path, is expected to be complete in late January.
The new bridge has been named the Hugo Throssell VC Bridge, after a Victoria Cross recipient and World War I hero.
Throssell was awarded the Victoria Cross for an action at Hill 60 on 29-30 August 1915 where he was wounded twice.
He was the first Western Australian to be awarded a Victoria Cross during the First World War and is the only Australian light horseman to receive this honour.
More than 30,000 vehicles use the Armadale Road and Nicholson Road intersection every day, of which 11 per cent are heavy vehicles, and from 2014 to 2018 there were 132 crashes.
Western Australian Premier Mark McGowan said the duplication project was a boon for local jobs.
"The $145 million Armadale Road Upgrade project was one of my Government's key election commitments and I'm pleased the dual carriageway is expected to be open before the end of the year," Mr McGowan said.
"The project has supported over 850 local jobs and will help ease congestion for southern suburbs residents.
"The new Hugo Throssell VC Bridge pays tribute to a remarkable Western Australian who received the Victoria Cross in 1915, for his acts of bravery during military action in World War I.
"Since becoming Premier I have always wanted to name something after Hugo Throssell VC - this is a fitting tribute to a great Western Australian."
Federal Minister for Population, Cities and Urban Infrastructure Alan Tudge said it was fitting that the project would pay tribute to one of Western Australia's greatest war heroes.
"The Armadale Road Upgrade project will save motorists up to 40 minutes a week during peak travel times. That is more time at home, more time with your family doing what's important," Mr Tudge said.
"Since 2013, we have committed over $13.5 billion towards land transport infrastructure projects in WA."
WA Transport Minister Rita Saffioti said the duplication would improve access to residential and commercial areas.
"The Armadale Road transformation has been underway since March 2018, with today marking a major milestone for the new Hugo Throssell VC Bridge at the Armadale Road and Nicholson Road intersection," Ms Saffioti said.
"The imminent completion of this project is a win for our southern suburbs residents, resulting in improved access to residential developments, Cockburn Train Station, Cockburn Gateway Shopping Centre and the Jandakot light industrial area.
"The dual-carriageway will benefit growing suburbs like Harrisdale, Treeby and Piara Waters which are populated by many young, working families.
"Armadale Road is an increasingly important connector between the key urban centres of Armadale and Cockburn.
"It's an exciting time for our southern suburbs as we continue to reduce congestion and create safer and more efficient journeys around our suburbs."
Senator for Western Australia Matt O'Sullivan said the bridge was only one of several infrastructure projects underway in the region.
"Today's bridge naming will ensure Hugo Throssell's name continues to live on, as it deserves to," Senator O'Sullivan said.
"Further west on Armadale Road, the Armadale Road and North Lake Road Bridge project over the Kwinana Freeway recently started construction, bringing further benefits and connectivity to the region."
The impressive bridge structure and its approaches extend 500m in length, with its 424 panels reaching 8.5m in height. Sixteen beams were used, weighing 122 tonnes each and spanning 32m in length, requiring two cranes to lift each into place.
The bridge forms part of the larger Armadale Road Upgrade project that includes widening the 6.9-kilometre section from Tapper Road to Anstey Road; the last section of single carriageway on Armadale Road.
As a whole, the Armadale Road Upgrade project will deliver a five-minute travel saving for 7,200 road users in morning peak and a three-minute saving for 7,800 road users in the afternoon peak.
Other intersection upgrades include the new Taylor Road and Wright Road roundabout at Armadale Road, which was opened to traffic on 9 September, and the new three-way roundabout at Liddelow Road.
Work to finalise the project will continue throughout January 2020 to finalise the median and verge works and the Principal Shared Path.
The $145 million project is jointly-funded by the Australian ($116 million) and WA ($29 million) governments.
Premier's office - 6552 5000
Transport Minister's office - 6552 5500
