Why Australia’s Giant Tunnel Machine Keeps Getting Stuck

It's 11 metres across, longer than a city block, and built to dig 30 metres a day. In four years it has been bogged, swallowed by a sinkhole and wedged in solid rock. Under Kosciuszko National Park, a tunnel boring machine called Florence is digging the 16 km headrace tunnel for Snowy 2.0. She has spent far more time stopped than moving. First the ground was too soft. Then the rock was too hard. We look at how a machine like this works and why it cannot simply reverse out of trouble, the sinkhole that opened above the tunnel in December 2022, the fault zone that pinched her shield in 2024 and the water jets that cut her free, what all of this has done to a project whose cost estimate went from about $2 billion to around $12 billion, and the week in 2025 when the machines were stopped by something other than rock. 00:00 A machine in a sinkhole 01:46 The short answer 02:24 Was it the wrong machine? 03:44 Bore, line, support, repeat 04:50 Why it cannot reverse 06:07 Enemy one: ground too soft 07:20 Enemy two: rock too hard 08:45 Bad luck or bad plan? 10:13 Stopped by people, not rock 11:30 The real reason • Snowy Hydro, Snowy 2.0 Tunnel Boring Machines (fact sheet) • RenewEconomy, Once too soft, now too hard: Snowy 2.0 tunnelling machine Florence comes to a stop again • RenewEconomy, Another delay: work stopped at all Snowy 2.0 tunnels over safety worries #tunnelboringmachine #australia