Note – this wasn’t a traditional breakthrough and an excavator was brought in to excavate the retrieval shaft in which the TBM had been sitting for about a year’s time.
On July 10, the 1st of 2 Robbins Tunnel Boring Machines, operated by the CEC-CICI JV to build Jaipur Metro’s 2.35 km UG-1B package, revealed itself to workers after excavation work concluded on the eastern shaft of Line-1’s Badi Chaupar Station.
This Ø6.52m Earth Pressure Balance TBM was commissioned from the operational Chandpole Station’s north shaft in June 2015 to build the up-line tunnel under the city’s historic district and had to be operated with utmost precision. Geology for the contractor was not a concern as it comprised of silty sand and minor amounts of gravel & clay.
The TBM took a long time due to the presence of weak heritage buildings (such as the 300 year old Chandpol Gate) strewn throughout its influence zone and the painful relocation of 13 temples on sites earmarked for the Chhoti Chaupar and Badi Chaupar Stations. As such, the TBM sat idle at different places at different times, including inside the TBM retrieval shaft for about a year waiting for excavation work to commence and be completed.
Images of this TBM (serial# 215-323) shot prior to its assembly can be viewed here.
Here are some images of soil being excavated to reveal the TBM’s cutterhead –
Post-excavation & cleanup images shot on July 10 –
For more updates, check out the Jaipur section of the The Metro Rail Guy!