Chatswood to Sydenham
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The Chatswood to Sydenham component of Sydney Metro City & Southwest involves the construction and operation of a new metro rail line from Chatswood under Sydney Harbour and through Sydney’s CBD out to Sydenham.
Tunnelling under Sydney Harbour
A specialised tunnel boring machine (TBM) designed for the geological conditions under Sydney Harbour excavated twin metro rail tunnels from Barangaroo to Blues Point.
![Sydney Metro Tunnel Depths infographic.](https://www.sydneymetro.info/sites/default/files/styles/media_tiles/public/2021-10/MicrosoftTeams-image%20%2829%29.png?h=e3823f31&itok=DNLePJmx)
How Sydney Metro's tunnel depths compare to other tunnels across Sydney. View text version of this diagram.
![Sydney Metro Tunnel Depths infographic.](/sites/default/files/styles/media_gallery_lightbox/public/2021-10/MicrosoftTeams-image%20%2829%29.png?h=30d1631d&itok=QO73xB9V)
![Infographic: Retrieving a TBM at Blues Point. 1. Excavation of a shaft to tunnel level. In 12 months, excavators and other equipment used to dig shaft to tunnel level. 2. Extraction of tunnel boring machine. TBM is dismantled and removed via the shaft using a crane, TBM cuts through to tunnel shaft. This process takes 1 month per TBM. 3. Shaft will be backfilled and parkland reinstated. Once TBMs have been removed the site will be returned to the community with no further use by the project (3 months).](https://www.sydneymetro.info/sites/default/files/styles/media_tiles/public/2021-09/BluesPoint%2520TBM%2520retrieval.jpg?h=76cfa167&itok=pjkPLaqD)
How we retrieved the TBMs at Blues Point
![Infographic: Retrieving a TBM at Blues Point. 1. Excavation of a shaft to tunnel level. In 12 months, excavators and other equipment used to dig shaft to tunnel level. 2. Extraction of tunnel boring machine. TBM is dismantled and removed via the shaft using a crane, TBM cuts through to tunnel shaft. This process takes 1 month per TBM. 3. Shaft will be backfilled and parkland reinstated. Once TBMs have been removed the site will be returned to the community with no further use by the project (3 months).](/sites/default/files/styles/media_gallery_lightbox/public/2021-09/BluesPoint%2520TBM%2520retrieval.jpg?h=a7cd7d46&itok=1SBAyNAn)
Building the tunnels
TBMs were used to excavate 15.5 kilometres of new twin rail tunnels between Chatswood and Sydenham.
Sydney Metro City & Southwest required five TBMs. Two were launched and removed from the Chatswood and Marrickville dives sites, with the fifth from Barangaroo.
Building the stations
The new underground stations on Stage 2 of Sydney Metro are designed to be as close to the surface as possible to allow customers to get in and out easily. At Crows Nest, Barangaroo, Central and Waterloo the stations have been excavated from the surface in a cut-and-cover construction method. At Victoria Cross, Martin Place and Pitt Street the station caverns have been mined out underground.
![Animated diagram showing a digger underneath a station box. A man walks around on ground level near the station box construction.](https://www.sydneymetro.info/sites/default/files/styles/media_tiles/public/2021-09/16021%2520CSW%2520EIS_Excavate%2520the%2520station%2520box.jpg?h=374ec536&itok=sMbq8obg)
Excavating a station
![Animated diagram showing a digger underneath a station box. A man walks around on ground level near the station box construction.](/sites/default/files/styles/media_gallery_lightbox/public/2021-09/16021%2520CSW%2520EIS_Excavate%2520the%2520station%2520box.jpg?h=975cf065&itok=_m_rdQZb)
![Animated view of a single span cut-and-cover design showing the metro trains underground on their tracks. Written above: All station will be fully accessible for all customers and integrated with all transport modes. Metro Stations will be designed to provide safe and efficient interchange between transport modes, giving priority to pedestrians.](https://www.sydneymetro.info/sites/default/files/styles/media_tiles/public/2021-09/station%2520design1.jpg?h=374ec536&itok=m8HDMSDB)
Single span cut-and-cover design
![Animated view of a single span cut-and-cover design showing the metro trains underground on their tracks. Written above: All station will be fully accessible for all customers and integrated with all transport modes. Metro Stations will be designed to provide safe and efficient interchange between transport modes, giving priority to pedestrians.](/sites/default/files/styles/media_gallery_lightbox/public/2021-09/station%2520design1.jpg?h=c4d40057&itok=QBCJx17l)
![Single span mined station design animation. Written above is: The metro stations will be designed as either single-span or binocular caverns. A single-span mined cavern is proposed at Victoria Cross Station. Single-span cut-and-cover stations are proposed at Crows Nest, Barangaroo, Central and Waterloo. Binocular mined cavern stations are proposed at Martin Place and Pitt Street.](https://www.sydneymetro.info/sites/default/files/styles/media_tiles/public/2021-09/station%2520design2.jpg?itok=hDtAsou_)
Single span mined station design
![Single span mined station design animation. Written above is: The metro stations will be designed as either single-span or binocular caverns. A single-span mined cavern is proposed at Victoria Cross Station. Single-span cut-and-cover stations are proposed at Crows Nest, Barangaroo, Central and Waterloo. Binocular mined cavern stations are proposed at Martin Place and Pitt Street.](/sites/default/files/styles/media_gallery_lightbox/public/2021-09/station%2520design2.jpg?h=c4d40057&itok=p-HBX6u1)
![Text on image: The decision on what type of station cavern will be used is based mostly on constraints to the tunnel alignment such as building basements or other underground infrastructure. Sydney Metro also aims to keep stations as shallow as possible to minimise customer travel time from street level to station platform.](https://www.sydneymetro.info/sites/default/files/styles/media_tiles/public/2021-09/station%2520design3.jpg?itok=WSJfE2a-)
Binocular mined design
![Text on image: The decision on what type of station cavern will be used is based mostly on constraints to the tunnel alignment such as building basements or other underground infrastructure. Sydney Metro also aims to keep stations as shallow as possible to minimise customer travel time from street level to station platform.](/sites/default/files/styles/media_gallery_lightbox/public/2021-09/station%2520design3.jpg?itok=KGVBGo-E)
Laying the tracks
Track laying in the 15.5km twin tunnels between Chatswood and Sydenham for the Sydney Metro City & Southwest project has been completed.
Construction of the tracks took 18 months and more than 500 workers to complete. More than 40,000 cubic metres of concrete - enough to fill more than 16 Olympic swimming pools – was used to embed about 45,000 sleepers which supported 62 kilometres of Australian steel rails with a combined weight of about 4,000 tonnes.