It’s a rare sight in the middle of Australia’s biggest city; an excavator hanging 30m above Castlereagh Street in the Sydney CBD, being carefully craned to a nearby rooftop. This middle- of-the-night precision operation signalled the start of major construction activity on Sydney Metro – Australia’s biggest public transport project.

Before tunnelling can begin on this city-shaping project, 17 city buildings are being demolished to make way for the new metro stations at Martin Place and Pitt Street.

They’re just two of 31 metro stations and 66km of new metro rail that will be fully operational by 2024 in this $20 billion-plus infrastructure investment – the biggest urban rail project ever built in Australia.

The first 13 Sydney Metro stations open in the first half of 2019 when the $8.3 billion Sydney Metro Northwest project comes online in the booming Hills region in the city’s North West.

It’ll be the region’s first reliable mass transit system in an area which has the highest private car ownership rate in the country and which, in coming decades, will be twice the size of Canberra.

From the North West, Sydney Metro is being extended under Sydney Harbour, through new CBD stations and beyond to Bankstown in this world-class once-in-a-century city-shaping program of works.

Almost 100 years ago, engineer Dr JJC Bradfield had to effectively do open heart surgery on the Sydney CBD to build the new city railway line, digging up streets and entire areas around Wynyard and Hyde Park.

Sydney Metro Program Director Rodd Staples said they now have a keyhole surgery-type approach now, which allows them to be more targeted.

“For a station at, say, Martin Place, we’ve acquired buildings at either end and we’ll be digging down … a basement excavation … and we then essentially mine to the halfway mark from each direction, to minimise the amount of construction activity that happens on the surface.

“The stations are almost two football fields long in length, so they’re quite large underneath the ground. You won’t see much of that construction going on, essentially because we’ve come in from the goalposts at each end.”

The demolition of the city buildings is being done from the top down with excavators craned to the rooftops bringing buildings down floor-by-floor.

Sydney Metro is using the best technology available to reduce construction impacts so people can go about their daily lives.

This includes state-of-the-art pulverisers and shears – jaw-like devices attached to excavators that can smash, cut and grind away material into small pieces.

Once the sites are ready, it’ll be time for the mega tunnel boring machines (TBMs) to come through as they deliver 15.5km twin railway tunnels Chatswood and Sydenham.

Five TBMs are being used – the most ever used at once on an Australian transport infrastructure project – with the first to be in the ground by the end of next year.

Two TBMs will tunnel for about 6km from Chatswood to the edge of Sydney Harbour. Another two TBMs will tunnel for about 8km from Marrickville to the new Barangaroo Station site.

And a specialised TBM, designed specifically to tunnel under Sydney Harbour, will tunnel up to 42m below the harbour surface from Barangaroo for about 1km to Blues Point.

There, the TBM will be retrieved and taken back to Barangaroo before being relaunched to build the twin tunnel.

Tunnelling under Sydney Harbour has been years in the making. Back in 2015, 53 marine exploratory holes were dug so experts could assess all the information about the geological conditions.

The boreholes revealed charcoal and remnant timber, between 22 and 56m below sea level – the product of bushfires more than 63,000 years ago.

Many shells were also found such as oysters, mussels, gastropods and crab claws – all lay undisturbed 38m below sea level for more than 20,000 years.

The work also resulted in a new three dimensional map of the bottom of Sydney Harbour – revealing the rock level at the bottom of this section of the harbour, west of the Sydney Harbour Bridge, is about 16m lower than previously investigated.

All this information has helped in the massive task that lies ahead as twin new metro tunnels are threaded underneath Sydney Harbour and the heart of the CBD.

“Sydney Metro will revolutionise the way Australia’s biggest city travels, shaping its future growth,” NSW Transport and Infrastructure Minister Andrew Constance said.

“Metro means a new generation of world-class fast, safe and reliable trains easily connecting customers to where they want to go.”

When services start in 2019, customers won’t need timetables – they’ll just turn up and go with a train every four minutes in the peak.

Designed to grow with the city, it will serve for generations to come, Sydney Metro will have an ultimate future capacity of a train every two minutes in each direction under the CBD and the ability to move more than 40,000 people an hour each way; significantly more than the 23,000 reliable capacity of each existing Sydney train line.

Sydney Metro will work together with the existing Sydney rail network to boost the number of trains entering the Sydney CBD in the morning peak hour by 60 per cent, to 200 trains an hour, creating capacity for an extra 100,000 people an hour.

So far, more than 32km of new metro railway tracks have been laid on the Sydney Metro Northwest project as major construction continues on 17 sites across the North West alone.

The first of Sydney’s new metro trains has been delivered to Sydney Metro HQ at Rouse Hill, where it will undergo commissioning and testing over coming months.

The fully-automated trains are another Australian first, bringing highly-reliable technology used around the world for decades here for the first time; platform screen doors, which keep people and objects away from the tracks, will also be used for the first time in Australia.

It’s full steam ahead on Sydney Metro as customers get ready to welcome a level of rail service never before seen in Australia.

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