Thornlie-Cockburn Link: Beyond connecting the dots

Artist’s impression of the future Nicholson Road Station.
Artist’s impression of the future Nicholson Road Station. Image: Supplied by METRONET.

When the Thornlie-Cockburn Link, the new passenger rail being delivered by METRONET between Thornlie and Cockburn stations in Perth, gets completed in 2024, it will be Perth’s first east-west rail connection that joins two existing train lines.

But that’s not the only first the project will be delivering.

The east-west rail connection linking the Mandurah Line with the Thornlie/Armadale lines will also, for the first time, allow residents in Perth’s south-eastern suburbs to catch the train to Optus Stadium, without needing to transfer through the Perth CBD.

Since the award of contract to the NEWest Alliance – consisting of CPB Contractors, the Downer Group and the Public Transport Authority – in December 2019, the METRONET Thornlie-Cockburn Link has also reached a number of milestones, including installing the state’s largest pre-cast concrete tee-roff bridge beams for the new Ranford Road Bridge in May 2021.

Scope of project

Looking at the Perth passenger rail network, it’s easy to see why an east-west connection between the existing north-south train lines makes sense. The radial design of the current passenger rail network creates gaps for residents in the Canning Vale, Cannington Strategic Metropolitan Centre, Burswood Peninsula and the eastern CBD. It also does not account for the expected growth in the region, where up to 102,860 people are expected to live by 2026, up from only about 72,000 in 2016.

Artist’s impression of the future Ranford Road Station.
Artist’s impression of the future Ranford Road Station. Image: Supplied by METRONET.

With affordable, urban-zoned land available, Perth’s south-eastern suburbs are expected to grow significantly. The area is also home to major industrial/commercial areas and prominent sporting clubs, such as the Australian Baseball League’s Perth Heat club based at Baseball Park (officially known as Perth Harley-Davidson Ballpark) in Thornlie.

The 17.5-kilometre Thornlie-Cockburn Link will duplicate three kilometres of track between Beckenham and Thornlie stations, relocate 11 kilometres of freight rail, build 14.5 kilometres of new passenger rail between Thornlie and Cockburn stations, build new stations at Nicholson Road and Ranford Road, and upgrade existing stations at Thornlie, Cockburn Central and Perth Stadium.

The two new stations will offer those who choose to live, work or play in the area more transport choice, which in 2031 will see an average weekday 2,350 boardings at Nicholson Road Station and 1,985 at Ranford Road Station.

Construction challenges

Working in a brownfields environment always comes with challenges and the Thornlie-Cockburn Link is no exception.

But the added complexity for this project comes from minimising disruption to the existing freight rail, which is being relocated to the northern part of the rail corridor to create enough space for the passenger rail to be built in the southern section. This freight line operates 24/7 and is an important contributor to Western Australia’s economy by connecting local businesses, communities and industries with eastern states and overseas markets. Through a highly coordinated construction schedule and collaborative arrangement between the state and freight rail operator, Arc Infrastructure, the rail freight will continue running safely and efficiently.

Over the coming months, work will begin to relocate sections of BP’s Kewdale White Oil Line, which transports fuel from BP’s Kwinana import terminal to Perth Airport. This work involves more than 11 kilometres of horizontal direction drilling and about one kilometre of open-cut trenching. The APA Group’s Parmelia Gas Pipeline has been relocated, as have various telecommunications, power, water and drainage assets.

Rail reserve service relocations at the future platform for the Thornlie-Cockburn Link at Cockburn Central Station.
Rail reserve service relocations at the future platform for the Thornlie-Cockburn Link at Cockburn Central Station. Image: Supplied by METRONET.

Construction novelties

As part of the METRONET Thornlie-Cockburn Link, a new higher and longer traffic bridge is being built at Ranford Road (near the new train station), over the existing rail corridor to accommodate both the electric passenger trains and the freight rail.

The bridge features the ten 50-metre tee-roff bridge beams, which are the largest ever built in Western Australia. These impressive beams were manufactured by Perth company, the Georgiou Group, at its precast yard in Hazelmere.

Seven of the 10 beams were installed over two days in May 2021, with the last three to be installed next year. Each beam consists of 14,000 kilograms of reinforced steel, 120 stressing tendons and 73 cubic metres of concrete; it weighs 197 tonnes and takes 10 workers and two concrete pump trucks three days to manufacture.

Tee-roff bridge beams being installed for the Ranford Road Station.
Tee-roff bridge beams being installed for the Ranford Road Station. Image: Supplied by METRONET.

Social and environmental considerations

During construction, the Thornlie-Cockburn Link will support around 1,680 jobs. This includes giving a number of trainees an opportunity to gain experience on one of Perth’s major infrastructure projects. Some trainees joined the project through the State Government’s ‘Infrastructure Ready’ training program, which gives job seekers the opportunity to learn on-the-job on Western Australia’s major projects.

Local suppliers are given plenty of opportunities to be part of this priority METRONET project, including Aboriginal businesses, with the project far exceeding the three per cent of contracts target.

To minimise the project’s footprint and reduce impacts to native vegetation and fauna, while some vegetation clearing was required, it has:

  • created native vegetation retention zones within construction and laydown areas to protect established vegetation;
  • collected native seeds before clearing started and provided to local government authorities to use in the area;
  • donated cleared native vegetation to various animal rescue organisations, including Cockburn’s Native ARC wildlife and rehabilitation centre and Kaarakin Black Cockatoo Conservation Centre;
  • relocated fauna before clearing begun;
  • established a program to inspect open trenches twice a day to remove any fauna that may enter the trench; and
  • commenced research into the movement and critical habitat identification for black cockatoos.

Recognising the local Noongar culture is an important part of METRONET project as part of METRONET’s Aboriginal Engagement Strategy (Gnarla Biddi) Strategy. Specifically, for the Thornlie-Cockburn Link, consultation through the METRONET Noongar Reference Group identified a preference to avoid impacts to the water hole at Nicholson Road Station.  Consequently, the car park design was revised to retain, enhance and celebrate the water hole within the site.

Artist’s impression aerial view of the future Ranford Road Station. Image: Supplied by METRONET.

With some residents sharing a fence line with the rail corridor, and others not too far away, the project will build almost eight kilometres of noise walls along certain sections of the rail corridor to reduce noise impacts. Where walls are to be built on property boundaries, in many cases to replace existing fences, extensive community engagement continues with owners and residents to construct the walls with minimal impact.

As a spokesperson from METRONET tells Roads & Infrastructure, the Thornlie-Cockburn Link is “all about making it easier for people living and working in Perth’s south-eastern suburbs by offering them more transport choices.”

“The link will address road congestion and positively influence land development to help deliver better planned and more liveable communities in Perth. A long-planned project, it will also support medium to long-term residential and employment development in the area.”

This article was originally published in the December edition of our magazine. To read the magazine, click here.

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