New construction method for Western Harbour Tunnel given the green light

The method to build Sydney’s third harbour crossing has been changed with the Department for Planning, Housing and Infrastructure (DPHI) giving the tick of approval to the Modification to the Western Harbour Tunnel project. 

The construction method for tunnelling under the Sydney Harbour between Birchgrove and Waverton has been changed from an Immersed Tube Tunnel to using tunnel boring machines (TBMs). 

This modification will reduce construction impacts on the community and environment by: 

• Not dredging in Sydney Harbour 
• Reducing the overall number of construction support sites by removing the need for construction support sites at Yurulbin Point, Berrys Bay, White Bay North and Victoria Road 
• Removing the need for cofferdams in Sydney Harbour at Birchgrove and Balls Head 
• Removing impacts to Birchgrove Ferry Wharf and ferry services 
• Reducing impacts to ferries and boats on Sydney Harbour 

“The use of TBMs is a positive change which will help minimise environmental and community impacts and maximise construction efficiency. 

“The approval to dig deep under the Sydney Harbour seabed means significant improvements for the environment and local communities compared to the previous plan to sink an immersed tube tunnel on the harbour floor. 

“The TBMs will be used to create twin 1.5-kilometre sections of tunnel under the Sydney Harbour. This will reduce the number of construction sites needed and minimise impacts on the harbour. It will also allow us to start work to deliver Berrys Bay parkland earlier, pending further consultation with the community and relevant approvals. 

“Using TBMs removes the need for dredging in Sydney Harbour, reducing the impact on the marine environment and surrounding communities,” a Transport for NSW spokesperson said. 

A new construction support site will now be established at Emu Plains where concrete segments for tunnel lining are going to be built and changes will be made to the existing support sites at the City West Link Portal, Glebe Island and Ridge Street, North Sydney. 

Other construction activities and elements of the approved project scope not included in the Modification Report will proceed as planned. The approved changes to project delivery are, however, subject to the Minister’s Conditions of Approval. 

The Western Harbour Tunnel is part of the State Government’s largest infrastructure program in history and it will create a western bypass of the Sydney CBD to help relieve pressure on the Sydney Harbour Bridge, Sydney Harbour Tunnel, Anzac Bridge and Western Distributor. 

The Western Harbour Tunnel project is being delivered in two stages. 

Construction of the first stage is being undertaken by John Holland and CPB Contractors. It involves the 1.7-kilometre southern section of the tunnel that connects Emily Street in Rozelle to Cove Street in Birchgrove. 

The contract to deliver Stage 2 was awarded to ACCIONA and the scope of works include the construction of the northern end of the tunnel along with connections to the Warringah Freeway near North Sydney, tunnelling under the Sydney Harbour and the complete fit-out of the twin tunnels. 

The Western Harbour Tunnel is anticipated to create around 6,900 full-time direct jobs during its construction phase. 

Source: Transport for NSW; NSW Government – Western Harbour Tunnel (1, 2); Infrastructure Magazine