Melbourne Metro: last TMB dismantled
14 October 2021The last of the Melbourne Metro Tunnel four tunnel boring machines (TBMs) completed its work back in May, breaking through at Town Hall Station in Melbourne’s CBD.
Dismantling the tunnel boring machines
After completing tunnelling at Town Hall Station, each machine underwent a dismantling process that lasted several weeks, breaking the machine down to its components to return to surface level.
The backup gantries, including mechanical and electrical components, were transported back through the completed tunnels to Anzac and Arden stations, where they were dismantled and each component reassessed for reuse.
The cutter heads were too big to remove from the stations intact. So, they were therefore cut into pieces using an oxyacetylene torch. Then, the pieces were sent to the scrap steel to be recycled.
The completion of the Melbourne Metro
Each TBM was equipped with a state-of-the-art navigation system to ensure accuracy in digging along the tunnel alignments. The TBMs were 7.28 m in diameter. They weighed more than 1,100 t and reached 120 m in length.
A crew of 10 people worked 24/7 on each TBM at any one time.
The metro tunnel project used mixed shield TBMs – commonly known as slurry TBMs. They are purpose-built to suit local ground conditions.
Once the TBM’s cutterhead bores through the ground, the excavated material will be mixed with slurry. The excavated material is then transported to the above-ground slurry treatment plant. Then, the excavated material is separated from the slurry and transported to a disposal site.
The next stage of the Melbourne Metro
Attention now turns to the next phase of work. The construction of the new stations is underway. The new High-Capacity Signalling system is being tested. It should then enable turn-up-and-go services.
The Melbourne Metro tunnel is expected to be completed by 2025.
Picture from the film “Tunnel boring machines dismantled “.
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