Shortlist for last WestConnex contract 29 Jun 2017

Two groups are shortlisted for the third and final major tunnelling and underground works package of the Aust$7.25 billion WestConnex M4-M5 highway link in Sydney, Australia.

Fig 1. Three phases of the WestConnex alignment

Following a successful call for expressions of interest in November last year (2016), Sydney Motorways Corporation, the private arms-length company established by the New South Wales Government to manage the $16.8 billion WestConnex highway mega-project and future highway projects in the State, has selected two joint venture to bid for design and construction of 7.5km of four-lane twin tunnel alignment between Haberfield and St Peters (Fig 1).

The shortlisted joint venture teams are:

• John Holland (Australia) /CPB Contractors (Australia)
• Lend Lease Engineering (Australia) /Samsung C&T (Korea)/ Buoygues (France)

Construction in two phases is scheduled to start next year (2018), although the exact route is yet to be finalised. Once completed in 2022, the new infrastructure will complete the underground link between the 5.5km of twin tunnels currently under construction for the $3.8 billion M4 link to the north and the $4.34 billion contract for the 9km M5 tunnels to the south. The M4-M5 link completes an unbroken 22km of highway tunnel infrastructure that will form the heart of Sydney’s new Western Bypass.

Roadheader excavation of M4 East tunnels

When the M4-M5 link was first conceived as Phase III of the WestConnex Project in 2013 it was expected that a mega-TBM of 14m diameter or greater would be procured for excavation of twin three-lane highway drives. Since then, project owner Sydney Motorways Corporation (SMC) has increased the number of lanes in each direction to four, implying a TBM of at least 16m diameter will be required, making them the largest diameter machines to ever operate in Australia.

In the latest project amendments, submitted to the planning authority in March this year (2017), SMC proposes the use of roadheader and/or TBM excavation, subject to design proposals submitted by the two bidding groups. Roadheader excavation is currently being used on the two current tunnel contracts with JV CPB/ Samsung C&T/ John Holland JV using 21 roadheaders for excavation of the M4 East tunnels, where excavation started in March 2016 and is currently just past the half way point; and the CPB/ Dragados/ Samsung C&T JV which has completed just more than 1,000m of a total 18km route of roadheader excavation from six headings.

Fig 2. Proposed Western Harbour Tunnel and Beaches Link Tunnel routes

The revised proposals for the M4-M5 link also call for construction of a 1km-long spur tunnel, plus associated ramps onto and off the main 7.5km-long Haberfield–St Peters tunnel, to be built as part of a separate underground works package. This Iron Cove Link will run as a spur from the Rozelle Interchange, and pass mostly underground under the old Rozelle Rail Yards out to Victoria Road near Iron Cove Bridge. Procurement for this second phase of the overall M4-M5 link is expected to progress in the coming months for award of contract and start of construction in 2019.

Alignment studies and concept proposals are also currently under development by the New South Wales Roads and Maritime Service for construction of a new Western Harbour Tunnel under Sydney Harbour, and the Beaches Link Tunnel under Middle Harbour that would connect the M2, M7 and northern beaches areas on the north side of the harbour with the M4 and M5 on the west and south side (Fig 2). The proposed new tunnels, which could stretch to 20km in total, will help relieve the Pacific Highway as it approaches the city via the Sydney Harbour Bridge crossing. Accidents on the bridge currently cause up to three-hour backlogs at the Lane Cove Tunnel and the Anzac Bridge.