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Sydney plans three harbour crossings 22 Nov 2014

Peter Kenyon, TunnelTalk

Sydney is advancing plans to spend a cash windfall on developing three under harbour crossings. A panel appointed by the New South Wales Government and charged with identifying the highest priority infrastructure projects in Sydney and the State recommends accelerating a rail tunnel by several years; advancing two further feasibility studies for separate road harbour crossings; and advancing more than 20km of twin running road and rail tunnels in the capital.

Fig 1. 12.5km underground alignment of SRT
Fig 1. 12.5km underground alignment of SRT

In June (2014) the State Premier charged Infrastructure New South Wales (INSW) with developing transportation recommendations as to how to spend a Aust$20 billion cash windfall that will be generated by the impending sale of 49% of the State’s electricity assets. The report, published recently, urges varying degrees of priority be given to three major tunnelling projects.

1. Sydney Rapid Transit Project (SRT)

This would comprise a 35km extension of the $8 billion North West Rail Link (NWRL) through the city centre and into the southern business district in Bankstown. Some 12.5km of the route would be aligned in a continuous twin-running tunnel that would also cross under Sydney Harbour (Fig 1).

It is recommended that the $3.4 billion in funding already earmarked for this project from the electricity windfall be doubled to $7 billion. Total construction cost is estimated at $10.5 billion, with the report suggesting that the project “can be brought forward by several years, commencing construction in 2017 and prior to the completion of the current 38km North West Rail Link.” The first two of four TBMs that will excavate the 15km underground section of the NWRL are already in operation on the project.

Fig 2. Sydney long term road transport plan
Fig 2. Sydney long term road transport plan
Fig 3. WestConnex moving to construction
Fig 3. WestConnex moving to construction

2. Western Harbour road tunnel and Northern West Connex Extension

This undercrossing of the Harbour, which is estimated in a pre-feasibility study at £4.5 billion, would link with a planned future toll WestConnex Northern Extension of the $11.5 billion WestConnex western bypass project that is currently moving towards construction (Fig 2).

The report concludes that the NSW Government Transport Department should develop a business case for the Western Harbour Tunnel by the end of next year (2015) “to enable the project’s procurement and delivery as a tollway in conjunction with, or immediately after, the delivery of WestConnex Stage 3”, that is by 2021 or earlier.

Fig 4. Current north Sydney road configuration
Fig 4. Current north Sydney road configuration
Spit Bridge over Middle Harbour
Spit Bridge over Middle Harbour

The first two phases of the WestConnex project, which involves extensive cut-and-cover tunnelling in Parramatta Road in Phase I as well as a new bored tunnel to the south in Phase II, involves upgrades to the M4 and M5 highways to the east of Sydney so as to create an effective western bypass. It will be completed in Phase III with an 8.5km twin TBM-bored tunnel that will link Phases I and II which are already in their construction procurement phase (Fig 3).

WestConnex Phase III is scheduled to move towards construction procurement in 2016, and the INSW report recommends that an initial business case for the WestConnex Northern Extension, already completed by the Government, be expanded into a “final business case” to be carried out by the WestConnex Delivery Authority “by the end of 2015.” The possibility of this extension then drives the urgent need for the suggested Western Harbour crossing. A southern extension of WestConnex is also highlighted.

3. Beaches Link toll road

The 9.3km stretch of road to the north of Sydney Harbour is one of the most congested in the city, with the current crossing of Middle Harbour, across the Spit Bridge, a particular choke point (Fig 4). INSW recommends the Beaches Link as a solution. With an estimate of $3.1 billion, the project would “likely use a tunnel connection for its full length from Seaforth to the Warringah Freeway corridor” to link the northern side of the planned Western Harbour tunnel with the suburbs as far as Seaforth. This would further create an effective north-south bypass (in conjunction with Westconnex and the Westconnex Northern Extension of the city) and provide easier access to the Sydney airport.

An undercrossing of Middle Harbour is proposed as part of the project, “although the option of a combined tunnel and bridge is also under consideration.” The report concludes that toll income alone would not pay for this project, and recommends that further review and development work be carried out with a view towards construction within a 10-20 year time frame.

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