On Monday evening, workers from Afcons Infrastructure commissioned their Robbins EPB Tunnel Boring Machine to build the up-line tunnel of Chennai Metro’s 2.4 km UAA-08 project from Washermenpet to Korrkupet as part of the 9.1 km northern extension of the 23.10 km Chennai Airport – Washermenpet line to Wimco Nagar which was approved by the Central Government in December 2015.
This TBM was previously used to build both the up-line and down-line tunnels between May Day Park – Central on package UAA-01. After its final breakthrough at Central Station in February 2016, it was dismantled and then brought to the Washermenpet Station’s northern shaft.
The TBM on its new assignment will first excavate towards Sir Theagaraya College Station and build 617 rings (1 ring = 1.4m) along the way for the up-line tunnel. At the time of writing this piece, the TBM has completed building 1 temporary ring within the shaft and 7 permanent rings.
Here are some images shot from on top of the extremely narrow shaft at Washermenpet. Note – the TBM seen below is TBM S711, a Herrenknecht machine also used previously in UAA-01, which will begin building the down-line tunnel in the coming weeks after assembly work is completed. The Robbins TBM is hidden below the concrete slab seen towards the back in images#2 & #3.
TBM S711 will start its northward journey in the coming weeks, so stay tuned for a similar post on that!
For more updates, check out the Chennai section of The Metro Rail Guy!