The project

The Sydney Harbour Tunnel project was a significant civil project, involving extended planning and huge construction and engineering feats. This page outlines the construction works and resulting road network features of the project.

Why build the Sydney Harbour Tunnel?

The Sydney Harbour Tunnel project was initiated in response to a need to:

• Alleviate increasing traffic congestion on the Sydney Harbour Bridge and its approaches.
• Provide for quicker travel times across the harbour.
• Free up space on the Sydney Harbour Bridge for a dedicated bus lane.

Outcomes

The major outcomes of the Sydney Harbour Tunnel project are:

• Construction of the 2.3 kilometre tunnel.
• A seamless connection between the Warringah Freeway on the northern side of Sydney Harbour and the Cahill Expressway, Eastern Distributor and Western Distributor on the southern side of the Harbour.
• Substantial alleviation of traffic congestion on the Sydney Harbour Bridge. According to 2005 figures, the annual average daily traffic volume for the tunnel was 86,800 vehicles with the bridge carrying 161,000 vehicles.

Snapshot of Sydney Harbour Tunnel Project

Major works

Major works undertaken during the project were:

• The construction of the northern portals (entry and exit) in the Warringah Freeway between High Street and Mount Street.
• The construction of the southern portals beneath the Cahill Expressway near Conservatorium Road.
• The construction of a ventilation system to supply fresh air and to remove exhaust air from the tunnel through ventilation shafts located inside the northern pylon of the Harbour Bridge.
• The construction of the tunnel, in three sections -
  • Twin 900 metre land tunnels on the north shore.
  • Twin 400 metre land tunnels on the south shore.
  • A 960 metre immersed tube (IMT) structure beneath Sydney Harbour.

The immersed tube structure consists of eight 120 metre pre-fabricated concrete sections sealed with a waterproof membrane. The structure was constructed in a dry dock at Port Kembla before being towed to Sydney Harbour and lowered into a 12 metre trench by a system of pontoons and control towers.

Who built the Sydney Harbour Tunnel?

The Sydney Harbour Tunnel Company owns, operates and will maintain the Harbour Tunnel until August 2022 when it is scheduled to revert to public ownership. The Sydney Harbour Tunnel Company contracted the Sydney Harbour Tunnel Joint Venture to design and construct the project.

Cost

$560 million

Sydney Harbour Tunnel and its use

• The Sydney Harbour Tunnel has been designed as a toll road. The RTA collects tolls for the tunnel as a subcontractor to Sydney Harbour Tunnel Company.
• The Sydney Harbour Tunnel has vertical clearance of 4.4 metres.

For more information about using the Sydney Harbour Tunnel go to Using Sydney’s Motorways.