Tunnelling depths and staging
North Melbourne to Kensington
In mid-2019, two tunnel boring machines (TBMs) were assembled at the Arden Station site and launched separately to tunnel towards the western tunnel entrance at Kensington.
In February 2020, the first TBM, Joan, arrived in Kensington and the second TBM, Meg, arrived in March.
The TBMS were transported back to site of Arden Station to be reassembled in early 2020.
In February 2020, the first TBM arrived in Kensington. Joan broke through at the shaft at Childers Street, where the second TBM, Meg, later arrived in March.
Before the TBM’s cutterhead 'broke through' into the retrieval shaft, the shaft was filled with water to balance groundwater levels while the TBM constructed the final section of tunnel. The water was then drained and the TBM retrieved. Water was then pumped back to the water treatment plant at Arden Station site via the TBM.
The TBM cutterhead and front shield sections were cleaned and disassembled using high pressure cleaners and hand tools before being removed from the retrieval shaft and loaded onto trucks using a crane.
The rear (gantry) sections of the TBMs travelled back to Arden Station through the constructed tunnel, and the rest of the oversized pieces were transported back at night by truck.
North Melbourne to CBD
In mid-May, TBM Joan launched from the Arden Station site and is now tunnelling towards Parkville and will eventually tunnel towards the CBD. Meg began her journey towards Parkville in June 2020.
Domain precinct to South Yarra
At the future Anzac Station in the Domain Precinct, TBMs Millie and Alice were assembled in the station box and launched separately to tunnel towards the new tunnel entrance at South Yarra. Millie was launched in April 2020, with Alice following in May.
Domain precinct to CBD
The TBMs will be reassembled in the station box and will start their journey towards the CBD, and under the Yarra River.