Excavation of the M4-M5 underground highway link between the new WestConnex M8 and M4 routes in Sydney, Australia, is on schedule to complete in mid-2021, after the first of six breakthroughs on the project occurred in January 2021. Lendlease-Samsung-Bouygues JV is using 28 roadheaders at various locations at depths of between 25m and 50m with 17km of the required 21km excavated to date.

An additional 22 roadheaders are working for John Holland-CPB Contractors on the underground Rozelle Interchange, the fourth element of the AUS$16.8 billion WestConnex project that will connect to the existing City West Link and the proposed new Western Harbour crossing (Fig 1). Roadheaders are progressing from four sites with excavation 40% complete on the 22km of road tunnels, caverns, ventilation structures, passages, substations and temporary access declines (Fig 2). With one breakthrough achieved, excavation is on track to complete in 2022.

Construction on both projects continues 24hr/day, seven days a week through Hawkesbury Sandstone, with some residual soils and weathered rock at the portals on the Rozelle contract. Roadheaders advance in a top heading and bench pattern with CT rockbolts and shotcrete applied as primary support.

Some areas of higher strength rock on the M4-M5 link route have been excavated using rock hammers. Blasting was considered with a small-scale trial undertaken in July 2020 but excavation has continued with road headers. No blasting is now expected on the project, Transport for New South Wales told TunnelTalk.

After opening of the M4 in 2019 and M8 in July 2020, the link highway and interchange are forecast to open in 2023 to complete the WestConnex project with drivers travelling 23km underground on the longest portal to portal route. North of the city, the 9km NorthConnex route opened in October 2020. Sydney will remain a hub for underground highway development with proposed new routes including new immersed tubes under Sydney and Middle Harbours and the 4km M6 Stage 1 route to connect south of the city to the M8 and the wider highway network.

Construction of the twin tube mainline tunnel to link underground the new M4 and M5 underground highways in Sydney, Australia, has been awarded to the LSB JV of Lendlease Engineering / Samsung C&T / Bouygues Construction. The design-build contract for the vital link of the city’s AUD$16.8 billion WestConnex highway project will include up to 7.5km of twin four-lane tunnels plus associated ramps and supporting operational facilities (Fig 1).

The contract is a part of the final stage of the WestConnex project with the Rozelle Interchange project which will be completed under separate contract. Together, the two parts of the final link have a budgeted estimate of AUD $7.2 billion.

Last month in May 2018 the project shortlisted two contractors for the final contract to design-build the Rozelle Interchange. The SCS JV of Salini Impregilo/Clough Projects/Samsung C&T and the JCL JV of John Holland/CPB Contractors /Lendlease will compete for the interchange contract which includes an underground motorway interchange to the WestConnex Link, an underground bypass of Victoria Road between Iron Cove Bridge and Anzac Bridge and a link for the proposed future Western Harbour Tunnel and Beaches Link project (Figs 1 and 2).

Speaking at the announcement of the contract award, WestConnex Minister Stuart Ayres said: “This is the crucial closing piece of this transformational infrastructure project that will help thousands of motorists everyday by easing congestion on M4, M5 and Parramatta Road. It will mean a quicker, safer and more reliable journey for commuters and 10,000 fewer trucks on Parramatta Road east of Concord. The link is the most important stage of WestConnex, providing a vital connection between two of Sydney’s busiest motorways, linking the New M4 at Haberfield with the New M5 at St Peters and creating a western bypass of the CBD (Fig 2).”

Work on the AUD$16.8 billion WestConnex highway project began in 2015 and comprises three other main contracts, which are either completed or progressing.

M4 motorway widening

Length: 7.5km between Parramatta and Homebush
Awarded to: CPB Contractors/Rizzani De Eccher JV
Contract value: AUD $498 million
Completed: 2017

New M4 underground motorway

Length: 6.5km with 5.5km aligned underground in twin-tube three-lane tunnels between Homebush and Hubberfield
Awarded in 2016 to: CPB Contractors/Samsung C&T/John Holland JV Construction
Contract value: AUD $3.8 billion
Progress: Excavation, using 21 roadheaders, completed December 2017, roadway paving now progressing

New M5 underground motorway

Length: 9km of twin three-lane tunnels from Kingsgrove to a new St Peters Interchange
Awarded in 2016 to: CPB Contractors/Dragados/Samsung C&T
Contract value: AUD $4.335 billion
Progress: Excavation by a fleet of roadheaders through favourable Hawksbury Sandstone about 50% complete with the first of six breakthroughs on the contract achieved in May 2018.

The LSB JV is selected to complete the M4-M5 Link project over its rival shortlisted group John Holland/CPB Contractors. On announcement of the Link contract to the LSB JV, Samsung C&T CEO Youngho Lee said: “It is a privilege to continue to work with the NSW Government to deliver this crucial project.” Samsung C&T is on the New M4 and New M5 JVs and is a JV partner with the shortlisted group for the Rozelle Interchange.

The full project is scheduled to be complete in 2023.

Construction of the AUD$16.8 billion WestConnex project in Sydney, Australia, is moving ahead with two joint ventures shortlisted for one of the final elements of the underground highway. The two JVs shortlisted for design-build of the Rozelle Interchange and Iron Cove Link on the M4-M5 Link Stage 3 of the project are:

• SCS joint venture - Salini Impregilo/ Clough Projects/ Samsung C&T
• JCL joint venture - John Holland / CPB Contractors / Lend Lease

The Rozelle Interchange is part of the final stage of the project to connect underground the new M4 and M5 underground highways. The interchange project, commissioned by the New South Wales Government, involves the construction of an underground motorway interchange at Rozelle and underground bypass of Victoria Road between Iron Cove Bridge and Anzac Bridge (Fig 1). It also includes links to the proposed future Western Harbour Tunnel and Beaches Link.

The WestConnex project, which will ease traffic congestion and improve access and connections to western Sydney, comprises five separate contracts delivered in three stages (Fig 2). Work started in early 2015 with the widening of the M4 motorway between Parramatta and Homebush and award of the 7.5km long $498 million contract in 2015 to the CPB Contractors / Rizzani De Eccher Joint Venture. This first part of the mega-project was completed in 2017.

Construction of the $3.8 billion M4 East stage of the project was awarded in 2016 to the CPB Contractors / Samsung C&T / John Holland JV and is 6.5k long, including5.5km three-lane twin tunnels. Excavation using 21 roadheaders across four sites was completed earlier this year after the first underground breakthrough in July 2017 and a further five breakthroughs across four tunnelling sites. Paving and M&E systems installation is now well under way. The underground extension of the M4 is scheduled to open to traffic in 2019.

The $4.335 billion New M5 Stage 2 of the project, to provide twin underground motorway tunnels of 9km long, from Kingsgrove to a new St Peters Interchange, was awarded for construction in September 2015 to the CPB Contractors / Dragados / Samsung Joint Venture. Excavation started in November 2016 and is progressing from three access points and using another fleet of roadheaders through the favourable Hawksbury Sandstone of the Sydney area. The first of six breakthroughs on the project was achieved in May 2018 and excavation is more than half way. The completed underground highway, which will duplicate the M5 East, more than doubling capacity along the corridor, is programmed to open to traffic in 2020.

The AUD$7.247 billion M4-M5 Link Stage 3 of the project comprises another 7.5km of twin mainline tunnels, of up to four lanes each, to link the M4 at Haberfield with the New M5 underground highway at St Peters (Fig 1). It also includes the Rozelle Interchange and Iron Cove Link, which features an interchange at Rozelle that will form the transitions between the underground highway and local surface roadways and provide for a future connection to the proposed Western Harbour Tunnel and Beaches Link, another major investment by the New South Wales State Government into the highway system of Sydney. The interchange in Rozelle will be mostly underground and located at the site of the old Rozelle Rail Yards. Construction of the mainline tunnels of the M4-M5 Link is yet to be awarded. Two consortia were shortlisted for the contract in June 2017:

• John Holland / CPB Contractors
• Lend Lease Engineering / Samsung C&T / Buoygues

Construction on the mainline tunnels is expected to start later this year with the Rozelle Interchange and Iron Cove Link to be completed by 2023.

“Construction on WestConnex is about one-third complete, with more than 22 million hours of work clocked up to date,” said Alesha Allen, Media Relations Manager for the project. “WestConnex will be the central spine of Sydney’s motorway network, providing a long awaited underground link between the M4 and M5, creating a seamless motorway without traffic lights. Accommodating through traffic of tens of thousands of vehicles per day, it will bypass up to 52 sets of traffic lights on current surface routes and reduce an average peak journey between Parramatta and Sydney Airport by up to 40 minutes.”

Australia is continuing its ambitious programme of underground infrastructure with underground works for road and rail progressing and being planned in each of the main States. As a projection, the Australian Industry Group has estimated an annual growth rate in roadwork projects in the country at about 21% for 2018-2019, and about 19% for rail projects. The Australian Government plans to invest about AUD$75 billion (US$56.4 billion) in public works, including roads, rail and other transport infrastructure, between 2018 and 2027, constituting about 9% of the gross domestic product.