This was published 1 year ago
Inside the new Metro tunnels snaking their way to the airport
Veteran borers Peggy and Eileen have been joined by the “Ferraris” of tunnelling on the $11b mega project. Here’s how it’s taking shape.
A 180-metre tunnel boring machine named Peggy broke through into the site excavated for the airport station terminal several weeks ago.Credit: Janie Barrett
Near the foot of the Blue Mountains, giant cranes tower over a new passenger terminal for Western Sydney Airport, dominating the landscape. Trucks and utes dart in all directions over the vast airport site as an army of workers clad in high-vis and hardhats toil away.
Unlike the multibillion-dollar airport rising from what were once paddocks, a massive hole dug several hundreds metres from the terminal is easy to miss from vantage points on the ground.
It is only when peering over the edge into the 28-metre-deep pit that the scale of the $11 billion project to connect the airport by rail to the rest of Sydney’s train network becomes clear.
Four massive boring machines are worming their way under fields, leaving in their wake concrete-lined twin tunnels for the Metro Western Sydney Airport rail line, which is due to open in just three years.
Workers in one of the rail tunnels at the site of the airport station.Credit: Janie Barrett
Metro Western Sydney Airport project director Angela Jeffery admits it is an ambitious timeframe, but emphasises that her team is on track to complete it in 2026 for the airport’s opening. “Because this is a brand-new railway, we were able to have some engineering efficiencies,” she said.
The main tunnelling work for the line, which is jointly funded by the state and federal governments, is due to be completed by the middle of next year.
Though not without challenges, the airport rail line is what is known as a greenfield project, which means it avoids the troubles of building in densely populated parts of Sydney that have beset the $21.5 billion Metro City and Southwest project.
Metro Western Sydney Airport project director Angela Jeffery and southern section project manager Vincent Ganet beside one of the boring machines.Credit: Janie Barrett
Digging a 200-metre-long hole in the ground for the airport station at Western Sydney Airport is easier than carving out caverns beneath office towers in the Sydney CBD for stations on the Metro City and Southwest line. It also avoids the latter project’s shutdown of an existing rail line.
Six stations will be constructed along the 23-kilometre airport line, which will be a combination of tunnels, surface and viaduct sections. All up, twin tunnels almost 10 kilometres long will be built.
Once opened, the airport terminal station will be a key stop on the line linking the airport to St Marys in the north, where it will connect to Sydney’s existing railway, and the planned city of Bradfield at Bringelly in the south.
The massive rectangular hole for the airport station is several hundred metres from the terminal, while a large shaft has been dug nearby to support logistics for tunnel boring machines. Credit: Janie Barrett
A trip on the driverless metro trains from the airport station to St Marys will take about 15 minutes, and a journey to Bradfield will be five minutes. The airport line’s trains will be about 30 centimetres wider than Sydney’s other metro trains to cater for flyers who are lugging bags.
For Jeffery, the project has a personal twist. She grew up several kilometres from the St Marys station site. “I’ve got the best job in town,” she said. “To see what the project will mean for the area is pretty amazing. It’s just phenomenal the government investment in western Sydney and to see it all happening at once is quite spectacular.”
The airport line has largely flown under the radar in comparison to the larger Metro West and Metro City and Southwest rail projects. However, it was savaged by the country’s peak infrastructure adviser two years ago, with a warning that the cost of the line would far outweigh the benefits.
The two giant tunnel boring machines – named Peggy and Eileen – at the airport station site are readying for their next move southwards. Peggy arrived several weeks ago after completing the first part of a 5.5-kilometre tunnel at the southern end of the line.
The two machines were previously used to tunnel from near Chatswood to Blues Point for the Metro City and Southwest project, the main part of which will open next year. They churned largely through sandstone on Sydney’s north shore for the earlier project, but are now tunnelling through shale in the outer west at an average speed of 120 metres a week.
When the machines dig through earth, conveyor belts carry spoil up to 4.5 kilometres through the tunnels they have created to gantries that take it to the surface for removal. Hundreds of precast concrete segments also sit in paddocks near the airport terminal, ready to be used for the tunnel walls.
Vincent Ganet, the project manager for the boring machines at the southern end, said the high demand for skilled workers and maintaining consistency within tunnelling teams were his major challenges.
“All projects are different. This one is a bit more challenging because of the market situation,” the Frenchman said. “We have got a market in Sydney which is really boiling. You can find a job wherever you want to go. The difficult part is retaining the good people.”
Ganet has also worked on tunnelling under Sydney Harbour for the Metro City and Southwest line, and before that on a massive sewer under the Thames in London.
Tai Maxwell, left, is working on one of the boring machines for the airport line project.Credit: Janie Barrett
At the northern end of the airport line, two other 180-metre boring machines are worming their way over 4.3 kilometres from Orchard Hills to St Marys where the ground conditions are softer.
Ganet describes those used on the northern section of the line as the Ferraris of tunnel boring machines. “Not because they look good but because they go really fast. You can go more or less twice as fast as the other ones,” he said.
Those on the northern section are known as earth pressure balance machines, which are designed to support the ground as they excavate through clay and shale rock.
About 16 people work on each of the tunnel boring machines at any one time. Two crews are assigned to each machine, and newcomers start at the back of them and gradually progress towards the front to work on jobs requiring more knowledge and experience.
“When it is tunnelling it can be warm and noisy. It’s a fast-paced environment,” Ganet said. “It’s a specialist industry – there are a lot of risks involved.”
Tunnel boring machine worker Tai Maxwell crossed the Tasman to work on Sydney’s airport line project after a stint on a rail tunnel project in central Auckland. He is working on Eileen, the boring machine which will soon start churning through rock again from the airport site.
“It’s pretty cool. You never know what to expect,” he said. “There is plenty of tunnelling going on – it’s definitely a good job to have.”
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