Final breakthrough on Sydney Metro Northwest

The Sydney Metro Northwest is Australia's biggest public transport project. Significant milestones are being achieved as it nears its anticipated completion date.For the past 16 months, Elizabeth, Florence, Isabelle and Maria have been hard at work excavating 30 kilometres of tunnel below Sydney’s northwest suburbs.

Named after Elizabeth Rouse, Florence Mary Taylor, Isabelle Anderson and Maria Lock – women who have made a positive contribution to life in Sydney – the four tunnel boring machines (TBMs) working on Sydney Metro Northwest have been integral to the progress of the momentous project.

The Sydney Metro Northwest is the first stage of the Sydney Metro project – the city’s new railway line. With 31 stations and more than 66 kilometres of new rail to be built between Rouse Hill in the city’s northwest and Bankstown in the southwest, the Sydney Metro is the country’s biggest public transport project. It will also be the first fully automated metro rail system in Australia.

The $8.3 billion Sydney Metro Northwest phase includes the construction of Australia’s longest railway tunnels – twin 15-kilometre tunnels from Bella Vista to Epping – as well as a four-kilometre elevated skytrain viaduct from Bella Vista to Rouse Hill. The scope of works also encompasses eight new railway stations, five upgraded stations and 4000 commuter car parking spaces.

To undertake such an expansive tunnelling project, the New South Wales Government selected TBMs as the most effective tool for the job.

The NSW Government awarded a Thiess John Holland Dragados (TJHD) consortium the $1.15 billion tunnelling contract for Sydney Metro Northwest in June 2014. The consortium, now known as CPB Contractors John Holland Dragados joint venture, undertook a global procurement effort to source four custom-made TBMs that could safely and reliably cut through the tough Sydney sandstone and shale, and progress at an average rate of 120 metres a week.

TJHD chose French-based firm NFM Technologies to manufacture the four TBMs. Precision components were pre-assembled in Le Creusot, France, while the cutter-heads and backup trailers were built by NFM in China.

The TBMs were shipped in 18 shipping containers as well as 27 separate large pieces and assembled on site to form the four 900-tonne machines required for the task at hand.

They were launched in stages to start building the twin 15-kilometre tunnels on schedule. Elizabeth and Florence began work in September and October 2014 respectively, digging nine kilometres from Bella Vista to Cherrybrook. Isabelle was launched from Cherrybrook in November 2014 and Maria set off in January 2015. Both TBMs excavated the six kilometres from Cherrybrook to Epping.

Terry Sleiman, Tunnels and Station Civil Works Project Director, explains that it was a demanding job from the get-go. “The real challenge of this job was to set up eight large scale construction sites and 15 kilometres of tunnelling under built-up residential and commercial areas in north-western Sydney,” he says. “This involved working closely with stakeholders to minimise the impacts of construction.”

Mr. Sleiman says that with many new tunnelling projects emerging, they set out to attract and train new workers. “We established the first tunnel training facility in Australia using state-of-the-art, three-dimensional visualisation to familiarise our workforce with their working environment.”

Each TBM was operated by a 15-man crew and worked 24 hours a day, averaging 173 metres of tunnel a week. With Elizabeth, Florence, Isabelle and Maria hard at work day and night and working concurrently for most of the time, the Sydney Metro Northwest became the first transport infrastructure project in Australian history to use four TBMs at once.

The machines burrowed through to create the seven-metre diameter tunnels (six metres when lined), lining them with concrete segments – manufactured at a new facility at Bella Vista – as they went. These segments were assembled underground into 16,000 concrete rings which were installed as the TBMs moved forward.

The custom-designed Bella Vista factory began producing the first of 100,000 concrete segments required for the tunnels in May 2014. The final segment came off the production line in November 2015.

The project used 29 kilometres of conveyor belts to remove about 1.8 million tonnes of spoil – soil, dirt and rubble that results from excavation. All of the spoil from the tunnelling was recycled and used on other infrastructure and environmental projects across greater western Sydney. None went to landfill. Much of the material was used in specific projects such as quarry remediation at Wallacia, industrial development at Riverstone and residential developments in six Sydney suburbs.

The tunnelling work was officially complete when Florence, the last TBM in operation on the project, arrived at what will become Cherrybrook Station in January 2016.

Mr. Sleiman says the project’s workforce has exceeded expectations. “From beating world benchmarks while producing 100,000 precast tunnel lining segments to constructing a massive underground cavern in difficult geotechnical conditions, the team has nailed it every time,” he says. “What makes our team so effective is the accountable and innovative culture that we established right from the beginning.”

This high-achieving culture led to the company winning awards for achievements in sustainability, training and community relations. “This reflects the high value we place on safety, training, quality, sustainable practices and our positive interactions with the communities around our worksites,” says Mr. Sleiman.

A key inclusion in Sydney Metro Northwest is the four-kilometre skytrain between Bella Vista and Rouse Hill, which is currently under construction.

In December 2013, Salini Impregilo was awarded the contract to build the skytrain rail line, including a 270-metre cable-stayed rail bridge and a further two kilometres of associated surface, civil construction works and railway embankments. It will be the first cable-stayed rail bridge to be built on a curve in Australia.

Two gantries are being used simultaneously in the construction, starting at each end of the planned line to reduce construction time.

The skytrain is expected to be completed in 2017 and the 36-kilometre Sydney Metro Northwest line will open in the first half of 2019.

Construction of Stage Two of the Sydney Metro project – Sydney Metro City and Southwest is scheduled to begin in 2017. This second phase includes a 30-kilometre extension of railway line from the end of Sydney Metro Northwest through new underground stations in the Sydney CBD then to the southwest. It is expected to open in 2024.

Andrew Constance, New South Wales Minister for Transport and Infrastructure praised the successes and achievements the project has made so far, and the significant impact it will have on the city.

“One by one we have ticked off the project milestones and we can see the light at the end of the tunnel with this aspect of the project almost complete,” he says. “Sydney Metro Northwest services will transform the way of life for people in this booming region of Sydney.”

This story has appeared in the Roads & Civil Works February/March 2016 edition – get your copy here today!

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