Bored tunnel approved for Sydney Harbour

The New South Wales Department of Planning, Housing and Infrastructure has approved the modification to the Western Harbour Tunnel Stage 2 project, changing the tunnelling method between Birchgrove and Waverton from an immersed tube tunnel to using TBMs.

Acciona, which has the design and construction contract, said the decision marked a significant step forward to build Sydney’s new harbour crossing in a way that significantly reduced the impact of construction on the community and environment.

This approval reduces construction impacts by not dredging in Sydney Harbour; reducing the overall number of construction support sites; removing the need for cofferdams in Sydney Harbour at Birchgrove and Balls Head; not impacting Birchgrove Ferry Wharf and ferry services; and reducing impacts to ferries and boats on Sydney Harbour.

Acciona started excavation on the project in November last year, launching the first of 10 roadheaders on the project to create a temporary access tunnel.

Western Harbour Tunnel is a 6.5km tunnel, designed to reduce traffic on the Sydney Harbour Bridge and tunnel by linking the Warringah Freeway with the soon to open Rozelle Interchange. It is the first new road crossing of the harbour in over 30 years.

The tunnel’s twin three-lane motorways are expected to reduce traffic on the Western Distributor by 35%, the harbour tunnel by 20% and the harbour bridge by 17%.

Stage one, which is under way, involves creating the 1.7km southern section of the tunnel from Rozelle to Birchgrove and is expected to be complete next year.

Stage two includes construction of the northern end of the tunnel, connections to the Warringah Freeway, tunnelling underneath Sydney Harbour and the complete tunnel fit-out. It is expected to take approximately five years.