Tunnelling

Sydney’s new metro railway will run through two purpose designed and built tunnels.

A number of factors determine the tunnel route and alignment. These include:

  • The location, depth and structure of the stations 

  • Vertical track grade 

  • Rock conditions 

  • Track curvature, to allow train speeds of up to 100 kilometres an hour
  • The physical constraints of the route, including crossing under Sydney Harbour.

Stage 1: Sydney Metro Northwest

Tunnelling finished in January 2016 on Australia’s longest railway tunnels – twin 15 kilometre tunnels from Bella Vista to Epping as part of Stage 1 of Sydney Metro.

Stage 2: Sydney Metro City & Southwest

Tunnelling will start in 2018 on the twin tunnels for Stage 2, from Chatswood to Sydenham, including under Sydney Harbour and through the central business district (CBD).

Australia's longest railway tunnels are finished

TBM2 Florence breaks through at Cherrybrook

About our tunnels

Sydney tunnel depths
Sydney tunnel depths

Sydney tunnel depths

Sydney tunnel depths
Inside the tunnels
Inside the tunnels

Inside the tunnels

Inside the tunnels
TBM4 breaking through at EppingPlay Video

30 km of tunnels in 3 minutes: Delivering Australia's longest railway tunnels

30 km of tunnels in 3 minutes: Delivering Australia's longest railway tunnels
How a TBM works
How a TBM works

How a typical TBM works

How a typical TBM works
Inside tunnel cavern
Inside tunnel cavern

Completed Castle Hill cavern

Completed Castle Hill cavern
Specialised TBM
Specialised TBM

A specialised TBM will be used to cross Sydney Harbour

A specialised TBM will be used to cross Sydney Harbour
TBM1 Elizabeth is retrieved from CherrybrookPlay Video

Dismantling TBM1 Elizabeth

Dismantling TBM1 Elizabeth
Tunnel cross-section
Tunnel cross-section

Sydney Metro tunnel cross section

Sydney Metro tunnel cross section

Our tunnel boring machines

Four mega tunnel boring machines (TBMs) built the twin tunnels on Sydney Metro Northwest, Stage 1 of Sydney Metro. This was the first time in Australian history four TBMs were used on the one transport infrastructure project.

On Stage 2, Sydney Metro City & Southwest, five TBMs are being used to deliver the tunnels between Chatswood and Sydenham. This includes a specialised TBM for the section under Sydney Harbour because of the ground and rock conditions found at the bottom of the harbour.

Naming the TBMs

On major tunnelling projects around the world, underground workers look to Saint Barbara for protection. Because of this, machines that work underground are traditionally given female names. Three of the four TBMs used in the Stage 1 tunnelling were named in public competitions under the theme: ‘Women who have made a positive contribution to life in Sydney’.

Completed tunnel

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Sydney Metro Northwest TBMs

TBM1 breaking through at Cherrybrook
TBM1 breaking through at Cherrybrook

TBM1 Elizabeth was named after colonial pioneer Elizabeth Rouse, by Alexandra Marshall from Rouse Hill Anglican College after winning a school competition.

TBM1 Elizabeth was named after colonial pioneer Elizabeth Rouse, by Alexandra Marshall from Rouse Hill Anglican College after winning a school competition.
TBM2 Florence breakthrough at Showground
TBM2 Florence breakthrough at Showground

TBM2 Florence was named after Australia’s first female engineer and architect, Florence Mary Taylor.

TBM2 Florence was named after Australia’s first female engineer and architect, Florence Mary Taylor.
TBM3 Isabelle breakthrough at Epping
TBM3 Isabelle breakthrough at Epping

TBM3 Isabelle was named after four-year old Isabelle Andersen by tunnel builders CPB John Holland Dragados. Isabelle represented the families
 of the tunnelling workers.

TBM3 Isabelle was named after four-year old Isabelle Andersen by tunnel builders CPB John Holland Dragados. Isabelle represented the families
 of the tunnelling workers.
TBM4 Maria breakthrough at Cheltenham
TBM4 Maria breakthrough at Cheltenham

TBM4 Maria was named after 19th century Aboriginal rights advocate Maria Lock.

TBM4 Maria was named after 19th century Aboriginal rights advocate Maria Lock.

Tunnel safety

Safety of customers is the number one priority. Tunnel safety measures include cross passages linking the twin tunnels and constant camera coverage. To find out more about tunnel safety in the Sydney Metro Northwest tunnels.

Tunnel safety

Tunnels Safety cross passages

Cross passages link the twin tunnels every 240 metres

Sydney Metro Trains Facility