After a series of accidents at construction sites, the Delhi Metro Rail Corporation (DMRC) had something to cheer about last week - the completion of India’s longest tunnel in an urban area by a consortium of Austria-based Alpine and Hindustan Construction Company (HCC), better known for constructing the Bandra-Worli Sea Link in Mumbai.
The 2.85-km tunnel has been constructed on DMRC’s 27.5-km Talkatora Garden-Buddha Jayanti Park line connecting City Centre and the international airport.
Of the 2.85 km, 180 metres were constructed using the traditional cut-and-cover method, in which the surface is cleared and a cavity created from the ground level. The work began in December 2007, with the sinking of three access shafts, one at each end of the tunnel and one in the middle.
The New Austrian Tunnelling Method (NATM) was used to construct the remaining portion of the tunnel. “This technology was used as it would have been difficult to employ tunnel-building machines in the area,” an HCC official said.
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