Melbourne West Gate highway approved 14 Dec 2017

Shani Wallis, TunnelTalk

The West Gate mega highway project in Melbourne, Australia, evolved this week from an unsolicited proposal submitted to the Victoria State Government by toll highway operator Transurban to an approved PPP project.

Fig 1. Route of the new West Gate highway
Fig 1. Route of the new West Gate highway

At the same time, the CPB/John Holland JV signed a contract as the selected construction partner of the project, and an order for supply of two 15.6m diameter TBMs to excavate the supersized twin tube, three-lane tunnels of the project is being finalized with Herrenknecht.

The project is promoted as a vital alternative to the existing West Gate Bridge southern access to the Melbourne business district, to routes north and to the Melbourne seaport, to take heavy truck traffic off residential streets in the west and cut severe congestion along the M1 highway corridor.

Having received the unsolicited proposal from Transurban in 2015 and in approving the project this week, the Labour State Government of Premier Daniel Andrews said that the proposal has passed through rigorous scrutiny after it agreed terms in December 2015 with the private infrastructure provider to develop the proposal through to preliminary design via a design-build construction procurement process and to run in parallel with local consultation and the planning and environmental review process.

Link to the M1 highway creates tubes of 2.8km and 4km long
Link to the M1 highway creates tubes of 2.8km and 4km long

According to a statement from the State Government, there have been “massive improvements to the project’s scope after five design updates, through two years of community consultation and as a result of a comprehensive environment assessment process”. The impact of the process is that an initial AUD$5.5 billion estimate of the project is now estimated at $6.7 billion, due also, it states, to the tunnels being “twice as long as the original business case, providing better city connections, with additional noise walls, and extending air quality monitoring for 10 years”.

Given the alignment of the new twin tube tunnels under the Maribyrnong River (a tributary of the Yarra River), and the connection of the new route with the existing M1 corridor, the two tubes have a different length with the shorter north tunnel at 2.8km long and the longer south tunnel at 4km.

Premier Daniel Andrews approved the project
Premier Daniel Andrews approved the project

The 50/50 CPB/John Holland JV was selected in early 2017 as the design-build constructor of the PPP project after a competitive tender process and ahead of rival bids from the JVs Bouygues Construction/Lend Lease Engineering and Salini-Impregilo/Fluor Australia/Lane Worldwide Infrastructure. Bouygues and John Holland are also working in JV with Lendlease Engineering and Capella Capital on the AUD$6 billion PPP contract for construction of the new 8.4km twin running tunnels and five underground stations for Melbourne’s new metro extension.

The shortlisted bidders for the RIA are CPB John Holland AECOM comprising CPB Contractors, John Holland, and AECOM Australia and Laing O’Rourke comprising Laing O’Rourke, Kellogg Brown & Root and WSP Australia.

As well as the lengths of surface work, the main element of the construction process is the twin tube mega-diameter tunnel and on the longer of tunnel options considered. TBM excavation was specified for the under river route and Herrenknecht is to supply two EPBMs from its manufacturing works in Shanghai, China. The machines are to be delivered towards the end of 2018 for launch in early 2019.

Northbound portal into the new West Gate highway tunnel from the M1
Northbound portal into the new West Gate highway tunnel from the M1

In agreeing development of the project in 2015, the State Government committed AUD$1.44 billion toward the total construction cost, with future toll income and a ten-year extension of Transurban’s toll road operation concession of the CityLink highway to the south and east of the city. The terms of the PPP are described in a statement from the State Government as having gone through rigorous market-led proposal guidelines to provide high value for taxpayers and drivers, with tolls increasing at a lower rate than agreed by the previous Liberal State Government of Jeff Kennett and by removing clauses that were to compensate Transurban for road projects that divert traffic off its network.

Legislation to operate the new highway and amend the CityLink concession deed is be introduced into State Parliament before the new highway is complete in 2022 and while Parliament is expected to support the project and its second river crossing, the contract allows for the State Government to pay for the road and its operation if Parliament opposes these changes.

Losing no time following the approval announcement, crews began moving into a construction compound in the Footscray area of the project and will begin construction of the northern tunnel portal in January. Following a 60-month program, the project is projected to open to traffic in 2022.

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