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Sunday, 7 May 2017

KMRC Fools the City , TBM Prerna has not even Entered Riverbed

We all knew TBM S640 Prerna has started boring under River Hooghly . But this is absolutely False !

Current Locations of TBMs


TBM S640 Prerna made a breakthrough at Howrah Shaft on 2nd February , 2017 ( Click here to view article ) . Kolkata Metro Rail Corporation , the body which is responsible for constructing the East West Metro has totally skipped the news to be in media that TBM Prerna had a breakdown while boring the Howrah Maidan - Howrah Tunnel . Making the news public would obviously make them a victim of Negative Comments. So they decided to hide everything related to this matter .

Can be declared as a 'Post-April Fool' !

Anyways , they didn't further delay the project and decided to skip the breakthrough of TBM S639 Rachna . Actually Rachna had a Hidden Breakthrough . Following is a short note on Hidden Breakthrough :-

What is Hidden Breakthrough ?

" Well , in case of a Hidden Breakthrough , the TBM is allowed to continue the tunnel boring works without actually making a Breakthrough . This thing is only done when the contractor can't complete digging the shaft in time . 

In such cases , the TBM safely continues boring the tunnel under the proposed shaft area , and workers continue to excavate the shaft . When they reach the depth of the tunnel , they simply dismantle the tunnel liners of the tunnel , which has been already bored by the TBM . 

Please comment your queries down below for further explanations regarding Hidden Breakthrough . "



KMRC has a target of boring both the tunnels under River within 15th June , 2017 , as Monsoons will hit the region after that resulting in further delay of construction.

Yesterday morning (6.5.2017) , AFCONS-Transtonnelstroy JV Commissioned their TBM S640 Prerna towards Riverbed from Howrah Shaft .

Please Note that By now , TBM S639 Rachna has bored more than 300 metres of tunnel under River Hooghly , just within 3 weeks ! 

The TBM is expected to complete tunneling before Monsoons . Following are some images from the Archives of Mr. Rupraj Sengupta :-

5 Tunnel Segments make a Tunnel ring . 
They are fixed with bolts all together for fast and Hassle Free Construction !

A Tunnel Segment Being casted in Casting Yard

TBM S639 Rachna 

Tunnel Segments being placed in the right place . 

Now , luckily TBM Prerna is fixed and is all set to be in the race of completing the tunnel !

Well , after reaching Kolkata , they'll be parked inside the tunnel in standby mode . Switching them off will collapse the tunnel as it may destroy the Earth Pressure Balance .


For More Updates of Kolkata Metro , please check Kolkata Metro Section ! Have a nice day !


----------- MetroRail Blog

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