Tunnelling through history: How Metro overcame odds in Old Delhi

From boring machines getting stuck during tunnelling work, stalling project timelines to evacuation of people from some of the most densly-populated areas, the road to the Walled City was not easy for the Delhi Metro, which surmounted these daunting challenges with innovation.

The transporter today said the Heritage Line (Central Secretariat-Kashmere Gate corridor of the Violet Line) was one of the shortest corridors (9.37 km) of the Phase-III network, but it turned out to be the "biggest challenge" in the phase.

"During tunnelling work between Delhi Gate and Jama Masjid stations, and at Azadpur station (of Pink Line), tunnel boring machines (TBMs) got stuck due to various constraints. We had to use innovative techniques to overcome them, so as to avoid the delay in the project," Delhi Metro Rail Corporation's Managing Director, Mangu Singh, said.

He was interacting with reporters at the launch of 'Delhi Metro: Phase-III Challenges', a compilation of the engineering feats achieved and the challenges encountered during the construction of the Heritage Line and two other major corridors -- Janakapuri West-Botanical Garden (Magenta Line) and Majlis Park-Shiv Vihar (Pink Line).

The Kalkaji Mandir-Botanical Garden stretch of the Magenta Line was inaugurated last December, while the Majlis Park-Durgabai Deshmukh South Campus section of the Pink Line was opened last month, taking the total operational span of the rapid transit network to 252 km.

Anuj Dayal, author of the volume and executive director (Corporate Communications) said the Phase-III project was initially supposed to only span 103 km, but with network expanding in Ghaziabad, Noida, Ballabgarh and other parts of the NCR, the length got extended to about 160 km.

"With Heritage Line and two of the recent corridors being opened, about 62 km of the Phase-III network has been covered. With completion of this phase, the operational span of the Delhi Metro will increase to over 360 km, and the Delhi Metro would rank five among the global rapid transit networks," Singh said.

Sharing the challenges faced in constructing the Heritage Line that passes through the historic Shahjehanabad area, dotted with numerous historic buildings, the Delhi Metro chief said, in a tunnelling stretch near the congested Golcha Cinema area, multiple TBMs had to be deployed to complete the job, after one TBM got stuck.

Besides, at Golcha shaft, TBM3 and TBM5 of 5.7 m diameter each were from a Chinese company, while TBM4 was of Herrenknecht with a diameter of 5.8 m.

So, to counter the issue of different diameters of TBMs, a 90 mm plate was welded inside TBM 3 and TBM5 to retain the uniformity of the tunnel, according to the publication.

Also, in the Old Daryaganj area, with a number of houses in dilapidated condition, local residents were evacuated twice during tunnelling on the Heritage Line.

"A total of 2,000 people were evacuated with around 650 people evacuated in a single go. They were put up in various guest houses in nearby areas, and the DMRC also repaired and restored their houses before shifting them back. Vertical support were given to all structures in the area during the tunnelling process," the publication said.

On ruins of the Akbarabadi Mosque being found under the Subhas Park in Daryaganj during the work, Dayal said, the entire alignment was changed and we had to go underneath the existing houses, so no geo-technical survey could be conducted there.

"We encountered granite rock underneath during the construction of the entire Heritage Line, but we overcame the odds and, New Delhi was connected to the heart of Old Delhi on the Metro network," he said.

At many locations, stations had to be redesigned, including at the upcoming Ashram Station on the Pink Line that passes though the busy Ring Road, a DMRC spokesperson said.

"At Ashram station the length of the station was turning out to be an issue in expanding the infrastructure, so we created a mezzanine floor there," he said.

After the completion of Phase-II also, a compendium of the major engineering challenges, was released and sent to all the major academic institutions and libraries, the spokesperson said.

"The DMRC had also made a documentary film on its Phase-2 challenges. The film had received a National Award ('Rajat Kamal) in 2011 in the 'Best Promotional Film: Non-Feature Films' category. An audio-visual documentation of Phase-III construction has also been done so that a similar film could be produced in the days to come," he said.