As Sydney Metro – Australia’s biggest public transport project – prepares for new rail services to start in the city’s booming north west next year, the next stage of delivering metro rail through Sydney’s central business district is now ramping up. With major construction activity now underway in the heart of the nation’s biggest – and busiest – city, the project team has implemented a number of technologies and measures to mitigate the impact of noise and vibration on the community.

Constructing deep beneath the city 

Demolition work is well underway at the new city metro station sites ahead of tunnelling starting, with the first of five mega tunnel boring machines to be in the ground before the end of this year.

The CBD stations at Barangaroo, Martin Place and Pitt Street will transform how people get around Sydney. Delivering new underground railway stations in the middle of a busy city presents its own challenges, with innovative techniques used to minimise impacts on key stakeholders from issues like noise and vibration.

The delivery of this 21st century railway has been likened to keyhole surgery, where builders will excavate stations in relatively confined sites and deliver most of the project deep beneath the city; a century ago, the City Circle was built more like open heart surgery where entire streets were excavated for the cut and cover tunnels which have served Sydney for almost 100 years.

Clearing space above ground
Bringing down tall buildings in a busy city has been a complex task, with the latest equipment brought in to minimise the impact on surrounding businesses, workers and residents as much as possible.

State-of-the-art pulverisers and concrete shears attached to excavators have been grinding away buildings, with these jaw-like devices significantly cutting the noise levels generated by traditional hydraulic hammering.

At the Pitt Street station northern entry site, the first major CBD demolition work has finished. Eight buildings were removed, the highest 14 storeys.

Over seven months, crews gradually brought down buildings on Castlereagh, Park and Pitt streets floor by floor, with excavators craned as high as 51m to carry out demolition from the top down.

During demolition, 21,000 tonnes of concrete, 5500 tonnes of bricks and 570 tonnes of steel were all recycled.

Reducing noise with acoustic sheds
Excavation is now taking place up to 20m below the surface with an acoustic shed minimising the impacts of construction noise on surrounding businesses and residents.

Once the sites are ready, the tunnel boring machines (TBMs) will come through as the twin 15.5km railway tunnels are built between Sydenham and Chatswood, including deep under Sydney Harbour.

The planning approval for the tunnels sets out strict conditions to minimise construction noise and vibration including acoustic sheds and noise barriers that are being installed at all tunnel construction sites.

Generally, people directly above the TBMs will feel slight vibration for a few days while tunnelling takes place below them with the Sydney Metro machines expected to tunnel an average of 120m a week.

Five mega borers will be used – the most ever used at once on an Australian transport infrastructure project – including a specialised TBM for under Sydney Harbour.

This machine will tunnel up to 42m below the harbour surface from Barangaroo, digging for about one kilometre to Blues Point. There, the TBM will be retrieved and taken back to Barangaroo before being relaunched to build the second tunnel.

Following community feedback during the planning process, barges will be used to remove crushed rock and machinery from Sydney Metro construction sites at Blues Point and Barangaroo, reducing the impact on the community.

The facility means more than 20,000 truck movements will be taken off busy inner-Sydney roads around Barangaroo and North Sydney.

A temporary barging facility has been approved next to the Parramatta River at Clyde and will be operated for about two years in the existing industrial area by tunnel builders John Holland CPB Ghella.

Crushed rock will be transferred to trucks at the facility, and transported to other residential and commercial development projects across wider Sydney, with 100 per cent of excavated material from the tunnels to be reused.

During tunnelling for the Sydney Metro tunnels in the city’s north west, all crushed rock was recycled back into commercial and residential projects in Greater Western Sydney like an environmental initiative at Prospect Reservoir and the construction of Bunnings Warehouse at Blacktown.

Safety is Sydney Metro’s number one priority, with Transport for NSW launching a new safety campaign for the greater Sydney metropolitan area given the increased amount of construction activity.

The Be Truck Aware campaign encourages pedestrians to take extra care around trucks and to avoid the distraction of mobile devices when crossing the road.

A city-shaping project
A $20 billion-plus program of many firsts, Sydney Metro will be Australia’s first fully-automated railway and will deliver technology like platform screen doors to Australia for the first time.

This new generation railway will have the capacity to move more than 40,000 people an hour, almost twice as many as an existing suburban railway line.

Services start in the first half of 2019 with a train every four minutes at peak times in the city’s north west on the $8.3 billion Sydney Metro Northwest line; eight new metro stations, five existing stations upgraded to metro standards and 4000 new commuter car spaces.

New metro rail will extend from the north west into the CBD and beyond in 2024, when Sydney will have 31 metro stations and a 66km new standalone railway system.

As well, the city-shaping Sydney Metro West line is in the early planning stages and will deliver a new underground link between the Sydney and Parramatta city centres in the second half of the 2020s, doubling rail capacity between these two key regions.

With an ultimate capacity of a train every two minutes in each direction under the city centre, Sydney Metro is the biggest urban rail infrastructure investment in Australian history.

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