The proposed Western Harbour Tunnel, a planned underground motorway scheme in Sydney, was approved by the Government of New South Wales (NSW) in Australia.

The planned tunnel and Warringah Freeway Upgrade received planning approval from the state government, marking a major step towards delivering the third road crossing of Sydney Harbour.

Overall, the project involves building a 6.5km tunnel with three lanes in each direction to mitigate congestion on the existing harbour bridge and tunnel, as well as on the Eastern Distributor and Anzac Bridge.

Once complete, the project is expected to reduce travel times from North Sydney to Sydney Olympic Park by up to 20 minutes.

NSW Minister for Transport and Roads Andrew Constance said: “The Western Harbour Tunnel will take pressure off the Sydney Harbour Bridge, Sydney Harbour Tunnel, Anzac Bridge and Western Distributor corridors to revolutionise transport capacity in and around our city.

“The new tunnel will start at the new Rozelle Interchange and head under the Harbour to the Warringah Freeway, and will integrate new and existing public transport connections.”

He added that the project will boost the state economy, as well as create around 15,000 full-time equivalent jobs.

NSW Minister for Planning and Public Spaces Rob Stokes said: “Planning approval means the NSW Government can get on with delivering the first stage, which is an upgrade to one of Sydney’s busiest and most complex road corridors, four kilometres of the Warringah Freeway.”

A local survey will be undertaken soon to identify ways to mitigate the impact of construction.

The construction is expected to start in the first quarter of this year, following the procurement process and contract awards.

Last month, NSW completed the $11.3bn Pacific Highway upgrade project.