Mumbai: Largest of the 20 giant TBMs to be deployed for Bullet train corridor

A whopping 20 Tunnel Boring Machines TBMs will be deployed by Afcons for various underground rail tunnel projects this financial yearThe company is building Indias first undersea rail tunnel in Mumbai for the ambitious Mumbai Ahmedabad High Speed Rail HSR project aka bullet train corridorThe HSR C2 Tunnelling package is daunting because it not only throws the gauntlet of constructing the countryrsquos first undersea tunnel but also the alignment between BKC and Vikhroli passes through a highly urbanised area making underground tunnelling a tricky affair The shaft excavations could prove challenging too since the shaft depths could go beyond 50 metresldquoA total of 17 TBMs are being mobilised this year and three more will be deployed early next yearrdquo said V Manivannan Afconsrsquo Director Construction Plant and Equipment CPE ldquoWe own all these TBMs and we are probably the only organisation in the country at present to own and deploy so many TBMs at a timerdquo he addsThe National HighSpeed Rail Corporation Limited NHSRCL recently signed a contract with Afcons for constructing Indiarsquos first undersea rail tunnel which is part of a 21KM long tunnel for the MumbaiAhmedabad bullet train project The undersea tunnel at Thane Creek will be 7 km long and around 25 to 65m below the ground level Sixteen kilometres of the tunnel will be executed using TBMs and five kilometres will be constructed with the New Austrian Tunnelling Methodology NATMldquoOur equipment fleet is strategic not generic in naturerdquo says Manivannan ldquoMost of our equipment is custom built and thatrsquos why we are capable of taking on technically challenging projects and completing them on time or ahead of schedulerdquo he adds One of the largest TBMs will be deployed for the construction of the HighSpeed Railrsquos C2 package ldquoA slurry TBM will be deployed with a diameter of 131m It will be one of the largest in the countryrdquo Manivannan saysConsidering that the undersea portion of the tunnel will fall under the intertidal zone it is possible that the water pressure could be high leading to extremely high overburden However Afcons has previously executed underwater tunnelling projects and has constructed the countryrsquos first underwater Metro tunnels below a river in KolkataAfcons constructed three underground Metro stations which are joined by two underground tunnels of 38 km each A portion of the tunnels mdash nearly 520M mdash is under the mighty river HooghlyldquoThe underwater tunnels are one of the biggest achievements in the EastWest Metro project in Kolkata We executed the project under poor geology and congested topography Before and after the river area the tunnels passed below several dilapidated buildings railway offices and yards busy roads bridges flyovers and heritage structures Our highly experienced tunnel crew made sure the TBMs were provisioned to shut down like a submarine in case of the slightest water ingress The underwater tunnels were completed in a record time of 66 daysrdquo he added