The most challenging underground tunnel work from the heart of the Pune city areas which are congested and packed with old structures-is set to start soon. The testing of the underground tunnel work has almost been completed from Swargate as well as on the side of the Civil court.
In an effort to avoid any calamity in the old city area, Pune Metro has completed building condition survey and clicked photographs of more than 1,000 structures including old wadas and buildings in this stretch.
Currently, there are two tunnel boring machines (TBM) that are working at Agriculture college ground, while two more machines will start digging the tunnel from Swargate.
There are four tunnel boring machines used to dig the 10-km underground tunnel from Agriculture college depot to Swargate underground station. The maximum tunnel depth is 30 metres which will be at the civil court station. It will take around 10 days to start the actual tunnel boring machine work.
According to Pune Metro officials, there was a challenge to make the New Austrian Tunnelling Method (NATM) towards Mandai from Swargate area.
It is a sequential excavation method or sprayed concrete lining method and the TBM setup is challenging due to the congestion and insufficient space at the site. This is when the NATM is preferred for tunnelling.
Three months to reach Mandai
Atul Gadgil, director, Maharashtra Metro Rail Corporation Ltd (MahaMetro) said, “There was a challenge to construct 150 metres of NATM work. After that, it was possible to start the TBM work. It was completed and was fully manual work. Now, we can start TBM work soon, It is mechanical and it is not challenging as compared to NATM.”
“The TBM work will start from both sides, Civil court and Swargate and it will meet at Mandai. From the Swargate site, it will take around three months to reach Mandai,” he added.
He further said, “We have completed our scientific study. There is nothing to worry about old structures or wadas on the ground of this underground stretch. We have an influence zone of 50 metres on either side of the tunnel. More than 1,000 structures fall in the influence zone.”
Metro photographs over 1,000 structures
Hemant Sonawane, general manager, public relations, Pune metro said, “We have conducted a building condition survey of Swargate to Civil court stretch. We have clicked pictures of the current condition of structures that are falling within the influence zone. It has been submitted to the concern building owners to keep a record of the structure before and after work.”
“It is a working procedure of underground work to check any damage or cracks after or during work. There is a possibility that people may register complaints of crack or damages of structure to Metro and claim compensation. At that time, we should have some record to verify the claim of people,” he added.