As the Mumbai Metro Rail Corporation (MMRC) prepares to begin operations of the fifth Tunnel Boring Machine (TBM) in the city, the first that began tunnelling on November 9 has completed 94.3 metres of boring as on Wednesday. By the end of this week, it is expected to complete 115 metres and then the machine will be stopped to complete its assembly underground.
“By January 14 or 15 the TBM should complete boring 115 metres into the ground. We will then stop the machine and assemble the remaining parts to commence its main drive. The complete assembly should take around 20-25 days and then it will resume again,” said SK Gupta, Director Projects, MMRC.
The entire length of the machine is around 110 metres, so due to paucity of space, only a part of the machine goes underground. Meanwhile, the remaining parts function from outside. Once the machine completes 115 metres, the entire machine is assembled together.
Krishna 1, as it has been named by MMRC, will be boring a 2.5 km tunnel between Naya Nagar and Dadar Metro station. Krishna 2, the second TBM to be launched from the Naya Nagar launching shaft, will bore a parallel tunnel.
The MMRC has named all the 17 TBMs in the seven packages after rivers flowing in Maharashtra as Surya, Vaitarna, Tanasa, Krishna, Godavari, Tapi and Wainganga. Each package has a minimum of two TBMs and a maximum of three.
Speaking about why the machines were named after rivers, Gupta said, “The rivers inspire us as they are a natural force, full of life. They carry essentials for life. Our tunnels will also flow the way the rivers do and carry passengers.”
While TBMs in some cities like Chennai are still referred to by numbers, in many other cities like Lucknow, Kolkata and Bengaluru they have been given names. In fact MMRC’s Krishna and Godavari have namesakes with Bengaluru Metro Rail Corporation (BMRC) TBMs.
“It is better to refer to the machines by names than by numbers as they are more relatable. There is a more personal connect with the machines when they have a name. While naming, we were only looking for names that are easy to recall and pronounce as everyone will now refer to them by these names,” added Gupta.
Meanwhile, MMRC is currently assembling the fifth and the sixth TBMs at Vidyanagari and Azad Maidan. Godavari, launched from Vidyanagari, will bore a 2.9 km tunnel till the domestic airport and Vaitarna 2, launched from Azad Maidan, will be tunnelling 4.5 km to Grant Road.
Of the 17 TBMs that will tunnel for the 33.5 km metro corridor, 13 have cleared the Factory Acceptance Test (FAT) and seven have already arrived in Mumbai. Of these, four are in operation at Azad Maidan, Naya Nagar and Pali Naka in Marol. Another two machines will be lowered in Marol and Vidyanagari in February. As Krishna 1 completed 94.3 metres of tunneling, Krishna 2 has completed 26 metres, Vaitarna 1 has completed 82 metres and Wainganga just began tunnelling on Monday.