A walk beneath Sydney Harbour: meet the Metro tunnellers

Forty metres below the ferries and yachts gliding across Sydney Harbour, a 100 metre-long machine and its small crew have been burrowing through rock, day and night, for months.

Thick wires and hissing pipes cover the long, train-like tunnel boring machine that chews away monotonously at sandstone and alluvial sludge deep below the harbour floor.

A worker operates the tunnel boring machine known as Kathleen, deep below Sydney Harbour.Credit: Nick Moir

The 800-metre long harbour tunnel it’s producing forms part of the Berejiklian government’s signature Metro rail project, which by 2024 will span a territory stretching from Sydney’s northwest, through the CBD and on to Bankstown.

The Metro’s scale and complexity hasn’t been contained beneath the city, with controversy over a multi-billion dollar blowout rearing its head at Macquarie Street, where the Premier has faced questions over her government’s ability to properly cost big infrastructure projects.

Transport Minister Andrew Constance has blamed an “overheated” contractor market and apologised for the $3 billion blowout on Australia’s biggest public transport project. He faces a grilling at estimates this Wednesday.

The politics swirling around the $15 billion Metro doesn’t bother Abdalah El Sayed, the project manager for the Barangaroo section, where a 30-metre drop into the ground is hidden behind an innocuous shed near Hotel Palisade.

The cavernous Barangaroo Crossover beneath Sydney.Credit: Nick Moir

“I’m a Sydneysider, I know my kids will use this,” he says, after we’re lowered into the cavernous expanse of the Barangaroo Crossover construction pit.

“I’m proud of what we’re doing down here, this is world class. We don’t pay attention to that stuff.”

The crossover, where trucks, forklifts and cement mixers move around beneath dripping rock walls, is massive. The imposing chamber gives way to two small, round tunnels at its northern and southern sides.

The bright, symmetrical passages are encased by sections of smooth cement. Each piece weighs three tonnes and connects perfectly with the next, forming a cylindrical jigsaw puzzle stretching hundreds of metres beneath Sydney Harbour towards Blues Point.

Abdalah El Sayed and engineer Jaime Cheuk walk down the Sydney metro tunnel. Credit: Nick Moir

The first tunnel was completed in October. The boring machine was disassembled, placed on a barge and sent back to the southern side, where it started tunnelling again earlier this year.

We follow Mr El Sayed, known as Abs, down the second machine-made burrow, which is yet to be completed. A few hundred metres down, we’re met by a forklift driver.

Engineer Jaime Cheuk sits in the 'manrider' vehicle as it travels towards the end of the metro tunnel.Credit: Nick Moir

“Abs, it’s all flooded,” the driver says, pointing to his vehicle, which is covered up to its halfway mark in water and sludge.

The tunnel bends slightly and then straightens out to reveal a small, brown lake stretching 100 metres or so across. Workers at the face of the tunnel half a kilometre away have opened the pipes that funnel a clay-like, watery mix into the face of the boring machine.

Thousands of litres have filled up the lowest point of the tunnel, so we need a truck to get to the other side.

Sitting in the “man rider” vehicle as it bumps and lurches down the Metro tunnel, engineer Jaime Cheuk says she would work deep underground all the time if she could.

Dallas Bell, the tunnelling machine operator.Credit: Nick Moir

“Tunnellers are like family,” she says, before muddy water washes through the doors of the vehicle and over our feet.

“Not many people can say they go under the harbour for work every day.”

Reaching the end of the tunnel, we’re met by a giant steel structure that takes up the entire width of the cavity: Kathleen, the boring machine. The 957-tonne machine is only 100 metres away from reaching the northern side of the harbour. Clay-covered workers clamber over thin gantries and spaces in the 130 metre-long piece of equipment as it cuts through the earth and slides sections of the tunnel jigsaw into place on its slow journey north.

It feels less like a tunnelling site down here and more like a submarine or an oil rig, with strange pumping noises and clinking of metal equipment echoing through the small tunnel.

“Thirty metres above us there are boats driving past,” Abs says.

Controlling the machine is Dallas Bell. He watches small screens that project digital shapes simulating and map Kathleen’s path.

Knobs and switches below the screen allow him to control the speed and direction of the individual sections of the cutter. Kathleen is the last of five boring machines that have been worming their way along a route beneath Sydney for years and is now less than a football ground away from her final destination.

Mr Bell will never see the rock wall he’s digging into, relying on the digital instruments to guide him, like a pilot landing in fog. “We land it every time though,” Abs laughs. Kathleen inches forward at about 30 millimetres a minute, Mr Bell says, cutting a path that will one day shoot Sydneysiders under the Harbour at 100 kilometres an hour.