Deeper Tunnels to be built for $5 Billion Western Harbor Tunnel

Deeper tunnels will be built beneath Sydney Harbour for a $5 billion highway after the NSW government abandoned earlier plans to lay large tubes in a trench on the harbour floor, allaying concerns about contaminated sediment dredging.

The government has signed a $4.24 billion contract with the Spanish company Acciona for the second stage of the Western Harbour Tunnel, which will involve digging part of the highway with two massive tunnel boring machines between Birchgrove and Waverton.

It is a reversal of earlier plans to lay so-called immersed tubes for the three-lane tunnels between Birchgrove and Balls Head on the harbour floor, a construction method like that used for the existing Harbour Tunnel more than three decades ago.

Metropolitan Roads Minister Natalie Ward stated that the government chose deeper tunnels because they were “more cost-effective for taxpayers” and eliminated the need for harbour dredging.

“We have the tunnel boring machine, which is more efficient, environmentally friendly, and cost-effective,” she explained.

“We’ve heard from the community about its concerns about harbour dredging.”