Tunnel boring work scheduled to begin for Pune metro line

While work on the elevated metro corridor is going on, Maharashtra Metro Rail Corporation Limited (Maha-Metro) has begun the work of 5.01 kilometre underground metro corridor passing from Agricultural College ground (Range Hills) to Swargate.

The agency on Friday conducted a site visit at Swargate for media persons to show the progress of underground metro work.

Atul Gadgil, Maha-Metro’s executive director, said, “Though the basic work of geo technical survey and vertical shafts is in final stages, the tunnel boring machines would arrive in the city soon. Four tunnel boring machines would be needed for this work and contractors are hiring it from metro works going on in other locations.”

Gadgil said that Maha-Metro has already awarded the underground metro work to contractors and the latter have started the work. The executing agency is erecting vertical shafts at Agriculture College grounds and Swargate.

Tunnel boring machines (TBM) of 6 meter diametre and 70-90 metres length would be used boring the underground tunnel. While two TBM will tunnel from Agriculture College ground end, another two will tunnel from Swargate.

According to a Maha-Metro official, it is expected that each machine would complete 6-metre tunnel per day. Cement concrete rings would also be erected simultaneously to strengthen the tunnel. Since it is hard rock, it would take little more time to dig the tunnel.

The official said that once TBMs have been lowered and after tunneling, all the four machines would meet at Budhwar Peth metro station.

Gadgil said that as no Indian company is manufacturing the tunnel boring machines, the assigned contractor would need to import these machines either from Germany, the US or China. The approximate cost of each machine is Rs60 to Rs70 crore. As metro works are going on in other Indian cities, contractors would hire these machines from other localities instead of purchasing new ones. 

“Hardly 10 to 15 men will work for underground metro work as tunnel boring machines are completely automated. All work, including boring, ring construction and removing the sand outside the tunnel is done by the machines,” said Gadgil.

The work of underground metro stations would start, but Maha-Metro would need open ground at metro station locations. Citizens will be able to see underground metro work only at station locations as the rest of the work will be carried out underground by tunnel boring machines, he said.

Gadgil said that Maha-Metro will monitor sound waves to ensure that no property on ground is damaged while tunneling work is in progress.