“They managed it with a whole range of contracts and multiple contracting types, which made it a little bit confusing but it was what they had to do to get going, and it’s gotten off with different forms of construction, bored tunnels, cut and cover tunnels, etc. There’s a really complex grade separation into existing railway lines.”
One of the challenges for the project is that Auckland is built on volcanoes “some of which erupted as recently as 800 years ago, which is very recent geologically”.
“So, to try and avoid some of the recent lava flows we built an incredibly complex geological model. We used the information that was available to us to plot the safest route. We used this model to locate the top striations, so to avoid some of the most recent lava flows. That was a very complex investigation and we have made that model available to the bidders.”
Another challenge is the current size of the infrastructure pipeline across a number of sectors in Australia and New Zealand.
Over an eighteen-month period, Sweeney tracked the pipeline from $80bn in September 2017 to more than double that in August 2018, and then $220bn in February 2019.
“I’ve never encountered this extent of growth and the way that this complicates what we have to do and the effect it has on our market is a real stretch. Certainly, historically New Zealand has built very little in 20 years and so, even getting major international contractors to take us seriously and come and bid for us was a big piece of work.”
However, early works are now “pretty much completed” according to Sweeney.
Moving forward, the agency has wrapped up the outstanding works – including the remaining tunnels, stations and rail systems infrastructure, as well as the related wider network and tracks – into one contract, Contract 3, to be delivered by a “Grand Alliance”.
The alliance consists of: Downer, AECOM, Tonkin + Taylor, WSP Opus, Soletanche Bachy, and Vinci Construction.
In October 2019, the demolition of thirty empty buildings demolished near the Mt Eden railway station began. This will ensure space for the construction of the southern portal for the City Rail Link’s twin tunnels. The cleared site will be used as a staging area for a Tunnel Boring Machine and other machinery.
The first phase of this demolition is due to be completed in March 2020 , and is being managed by the alliance.
During January, works towards Melbourne’s metro tunnel ramped up with crews working throughout the month to excavate the final section of the tunnel’s entrance and make room for the new track which will connect existing lines to the tunnel.
The crews will complete major concreting works at the tunnel entrance, pouring the final sections of the tunnel roof slab and installing the tunnel support structures.
“It’s now two years since we signed the contract and we’re well up and running at seven construction sites along the alignment,” Tunnel and Stations package director at Rail Projects Victoria, Linda Cantan, said.
As package director Cantan has overseen the procurement and contract negotiation for the $6bn package to build five new underground stations as well as the tunnel itself. She is responsible for managing the contract throughout construction.
A number of companies are building the tunnel, and construction is split across several work packages.
Early works to relocate services and prepare the construction sites were delivered by John Holland KBR. New tunnels and stations are being built through a Public Private Partnership, named the Cross Yarra Partnership consortium which includes: Lendlease Engineering, John Holland, Bouygues Construction and Capella Capital. Yarra Trams will deliver tram infrastructure works.
Rail systems including signalling and systems integration work will be provided
by CPB Contractors and Bombardier Transportation, while a consortium comprising John Holland, CPB Contractors and AECOM will deliver rail infrastructure works including the tunnel portals and realignment of existing rail lines.
The project is projected to be complete by 2025.
“We’re creating is a dedicated rail line between Sunbury and Dandenong. People ask why a dedicated rail line, by taking capacity out of the city loop we free up extensive capacity through the rest of the rail network.”
The Melbourne Metro Rail Project includes twin nine-kilometre rail tunnels between South Kensington and South Yarra and five new underground stations.
The project will take three of the busiest train lines (Cranbourne, Pakenham and Sunbury lines) through a new tunnel under the city and thus free up space in the city loop to run more trains in and out of the suburbs.
“We have 4 tunnel boring machines doing our tunnelling, which were launched from our two logistics sites at North Melbourne and Anzac Station. Meg and Joan are travelling out to the west at the moment.
“Joan has travelled 470 metres out of north Melbourne, and we’ve had to negotiate the city link viaduct under the Mooney Creek. Meg has gone about 137 metres. We’re also travelling along all of the rail network, so extensive work is needed to make sure we’re doing that in a safe way. To date progress has been very good and in fact the grand settlement has been better than predicted.
“On the eastern side of the alignment, we have Millie and Alice who will launch early next year. They’ve been delivered to Domain, beside Anzac station, and will launch in the first half of 2020. They will be heading out to the eastern portal, then be retrieved and brought back to be relaunched and head towards the city.”
“We’re in quite a narrow corridor and have retaining walls to build to ensure that there’s no settlement of the existing tracks, but we’re working in a very tight environment to create those exits and entrances to the tunnel structures. The PPP is constructing a shaft in that area for the TBM retrieval early in 2020.”
“We’re developing these stations for ten car, high capacity metro trains, which will be procured under a separate PPP. As such our construction boxes are about 250 metres long and the width, depending on the station, about 25 to 30 metres,” Cantan explains.
The Eastern tunnel entrance stops beyond South Yarra station as there is not enough room in the corridor.
“What we’re trying to do here is to put another two train lines in a very congested corridor, where we have multiple train lines coming in from the South East.
“This is another area where we have our Rail Infrastructure Alliance working alongside the PPP. The PPP can build their shaft, that will be used for the extraction of the TBM, right next to where the Rail Infrastructure Alliance are doing the cut and cover structure.”
“We’re now underground in a lot of locations so I keep saying to people: be patient with us because we don’t open till 2025, but we’re now underground, tunnelling, excavating and starting the build out of our stations,” Cantan concludes.