C.P. Singh is a jovial man who is happy to talk engineering when he has got his safety helmet on at a Metro construction site. He is the project manager of a crucial seven-kilometre stretch that connects Moti Bagh with Delhi Cantonment on the 59-km Majlis Park-Shiv Vihar corridor of the Delhi Metro. Unlike his previous stints that involved monitoring a section of the Violet Line that connects Nehru Place with Okhla and supervising the construction of the Metro Bhavan, this one is a tricky assignment.
It is along this stretch, exactly at Dhaula Kuan, that the Metro would reach its highest point so far of 23.6 metres above the ground - as high as a seven-storey building. At this point it will even surpass the viaduct that is constructed 19 metres above the ground at Karkarduma. The task is particularly tricky here since the line crosses the existing and functional Airport Express Line between pier 110 and pier 111. Thus, the launching operation of each of the 45-tonne segment that comes to the site from the Zakhira Casting Yard is done between 12:30 a.m. and 4 a.m. when the train services are not operational.
On most days, Mr. Singh works in the day, except at a “crucial night” like it will be on Thursday when the last of the segments, the 13 one, is scheduled to be launched. The segments have been erected through a special four-step method because of the extra height involved. “Instead of two steps like it is everywhere else, here it is four steps,” said Mr. Singh to a small group of journalists, who are on a site visit on Thursday afternoon.
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First, the trailer brings the segment and parks between the already constructed piers. Then the segment is lifted by an ‘extended winch assembly’ that can carry a load of 120 tonnes which then transfers the same to the extended Macalloy bars fixed to a slider that can launch the segment only up to a height of 15 metres. Here, Mr. Singh noticed the blank faces all around and started pointing at the design in his hands and the large launchers overhead to make things clear.
After a complicated transferring of segments it is rotated and attached with a segment trolley and slider and pushed to one end of the pier where it is to be erected, through a segment launcher. If the launch operation goes without any glitch on Thursday night like it has all these days, Mr. Singh will oversee the making of the epoxy-based glue that binds each segment together.
“Normally, launch operation of a segment takes half an hour but for this stretch that goes over the Airport Line, it has taken as much as three hours,” he said. “We have to make sure there is enough clearance between the bottom of the segment and the top of the overhead electrification wires of the Airport Line.”
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Later, Mr. Singh joined the reporters 23.6 metres above the ground, and pointed out the surroundings. Below were the layers of engineering marvels: the Ring Road, the flyover at Sardar Patel Marg, and the Airport Express line.