By rosebell
As the launch chambers for the largest twin TBMs in the southern hemisphere, construction of twin underground caverns at Birchgrove has been completed by crews working on Sydney’s Western Harbour Tunnel.
Being situated just 230m from the edge of Sydney Harbour, these two 28m-high caverns are among the largest ever dug in Australia.
Following arrival of the second TBM, Barangaroo, in Sydney on October 21 and joining its twin, Patyegarang, which landed in August, this landmark was achieved.
While excavation of a 1.5km route 50m beneath Sydney Harbour to the Warringah Freeway at North Sydney will be up to these TBMs, they are each 137m long and weigh more than 4,300 tonnes.
Benefiting a 500-tonne gantry crane, the process of assembling the TBMs inside the Birchgrove caverns is due to be done by workers during the coming months.
The scheduled date for commencing excavating by TBMs under the harbour is the first half of next year and are expected to take almost a year to complete their drives.
As the first new harbour road crossing in 30 years, the Western Harbour Tunnel is going to provide a 6.5km connection between the Warringah Freeway and the Rozelle Interchange, decreasing congestion and strengthening connections across the Sydney’s north, west and south.
According to Minister for roads Jenny Aitchison: “The project’s scale was breathtaking.The Western Harbour Tunnel TBMs are the largest in the Southern Hemisphere and the largest in the world to be assembled underground. The mega-machines were shipped to Australia in 263 pieces, with 125 shipping containers of other components, and our team is now preparing them for launch.
