The Sydney Harbour Tunnel is a twin-tube road tunnel in Sydney, Australia. The tunnel was completed and opened to traffic in August 1992 to provide a second vehicular crossing of Sydney Harbour to alleviate congestion on the

Sydney Harbour Bridge The Sydney Harbour Bridge is a steel through arch bridge in Sydney, spanning Sydney Harbour from the central business district (CBD) to the North Shore. The view of the bridge, the harbour, and the nearby Sydney Opera House is widely regarded ...

. It is one of two tunnels under the harbour, the other being a set of rail tunnels for the

Sydney Metro The Sydney Metro is a Automatic train operation, fully automated rapid transit system serving the city of Sydney, New South Wales, Australia. Currently consisting of Metro North West Line, one line that opened on 26 May 2019, it runs from Tall ...

. The tunnel joins the Warringah Freeway at North Sydney, and the

Cahill Expressway The Cahill Expressway is an urban freeway in Sydney and was the first freeway constructed in Australia, opening to traffic in 1958. It starts from the Eastern Distributor and Cross City Tunnel in Woolloomooloo, and runs through a series of ...

at the entrance to the Domain Tunnel. It has two lanes in each direction, and runs at an angle of approximately thirty degrees (North to South) to the Sydney Harbour Bridge, which has eight lanes, with a tidal flow operation. In 2008, the tunnel was carrying around 90,000 vehicles per day.

Construction

The tunnel is made up of three sections: twin land tunnels on the north shore, twin land tunnels on the south shore and a

immersed tube An immersed tube (or immersed tunnel) is a kind of undersea tunnel composed of segments, constructed elsewhere and floated to the tunnel site to be sunk into place and then linked together. They are commonly used for road and rail crossings of ...

(IMT) structure. The tunnel falls about from the northern entrance and about from the southern entrance to its deepest point, below sea level. The construction was undertaken by Thiess Contractors. The IMT structure consists of eight

precast concrete Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast be ...

units. The units were constructed over away in a casting basin at Port Kembla and then towed to Sydney Harbour. A trench was dredged before the arrival of the IMTs and then the IMTs were lowered into the trench by a system of pontoons and control towers. After the IMTs were in place the trenches were backfilled and then a rock armour was placed over the top to protect the units against marine hazards, such as anchors or sinking vessels. The land tunnels were constructed by a combination of driving and cut-and-cover techniques, designed to be strong enough to withstand the impact of earthquakes. The northern end pylons of the

were altered to allow for air exhaust from the tunnel to rise over the harbour. Bradfield Park on the northern side of the bridge also has air intakes. Fresh air is drawn by an underground ventilation station on the north shore and is pumped to all sections of the tunnel through vented ducts. The air supply uses fourteen axial flow fans, each up to in diameter. The exhaust uses sixteen (eight in each northern pylon tower) fans that draw exhaust air through two underground ducts from the tunnel ventilation station and transfer the air to the top of the pylon. They can expel it at up to – equivalent to changing all the air in the tunnel every two minutes with the capability of running in reverse in an emergency and all fans are rated for smoke extraction. Each of the fans has a duty of . The testing of the fans was one of the most comprehensive ever, covering flowrate and pressure, power measurements, sound levels, bearing vibration, x-raying of all impeller components, high-temperature tests at for 2 hours, impeller strain, and 24-hour run tests for reversals. The tunnel was opened to the public to walk through from North Sydney (Falcon Street) to Eastern Sydney (The Domain) on 30 August 1992. The proceeds of the tickets sold for this event were donated to the Royal Institute for Deaf and Blind Children. The tunnel opened to traffic on 31 August 1992.

Operations and maintenance

The Harbour Tunnel was a partnership between the New South Wales government and private investors by tender. Transfield Pty Limited and

Kumagai Gumi is a Japanese construction company founded in Fukui, Fukui Prefecture, Japan. The company still has registered headquarters in Fukui, but the actual head office is located in Shinjuku, Tokyo. History Santaro Kumagai, the company's founder, be ...

formed a 50/50 joint venture company which constructed the tunnel under contract; with a 30-year operating contract, including revenue collection and maintenance, from 1992 until 2022. As a result of the 1997 separation of assets of Transfield and the creation of the Tenix group (owned by Olbia), the ongoing thirty-year operating contract for management of the tunnel was split between Kumagai Gumi (50%), Transfield (25%) and Olbia (25%). The total construction cost of the project was A$554.25 million. $A223 million of this was an interest-free loan from the NSW Government, to be repaid at the conclusion of the operating contract in August 2022 when the tunnel would be transferred to public ownership. The government had also guaranteed an Ensured Revenue Stream (ERS) to the operator, whereby it makes up the shortfall between toll collections and the guaranteed amount. As toll revenues have been below the projected amount, in 2008 for example, the government paid the operator $58.9 million, with the total amount forecast to be $A1.1 billion from 2008 to 2022. The NSW Auditor-General had also raised concerns that the tunnel's expenses may make the operating company default on the $A223 million loan, however the government remained confident in it. With the 30-year operating contract about to expire, in April 2022, the state government signed a 15-year contract with Ventia for the asset management, operations and maintenance of the Sydney Harbour Tunnel as well as the under-construction Western Harbour Tunnel. Tolling arrangements were unrelated to the new agreement. On 1 September 2022, the tunnel reverted back to state government ownership.

Tolling

In 2006, the New South Wales Government announced that all cash tolls on the Sydney Orbital Network would cease by 2010. The Sydney Harbour Tunnel went fully electronic in July 2007 with both e-TAG and e-pass video tolling arrangements in use, similar to technologies used by the

Westlink M7 The Westlink M7 or M7 Motorway, formerly Western Sydney Orbital, is a tolled urban motorway in Sydney and is a part of the Sydney Orbital Network. Owned by the NorthWestern Roads (NWR) Group, it connects three motorways: M5 South-West Motor ...

, Cross City Tunnel and the

Lane Cove Tunnel The Lane Cove Tunnel is an A$1.1 billion, 3.6 km twin-tunnel tollway in Sydney, Australia, which connects the M2 Motorway at North Ryde with the Gore Hill Freeway at Artarmon. It is owned by toll road operator Transurban and forms ...

. This measure has substantially eased the traffic jams heading towards the electronic gantries, and providing increased convenience and time savings. The Sydney Harbour Tunnel attracts a varying toll (that was introduced in 2009) of between A$2.50 and A$4.00, depending on the time of day. The toll is levied on the southbound approach to the tunnel entrance. Until July 2022, it was unannounced whether tolls would continue after the transfer of ownership to the state government on 1 September 2022. It was eventually announced by the state government that the toll will continue, to be used for maintenance, just like the Sydney Harbour Bridge currently.

Exits and interchanges

References

External links