
Making of India's longest rail tunnel between Devprayag, Janasu in Uttarakhand face challenges; breakthrough achieved
The Hindu
India's longest rail tunnel faced challenges, including potential collapse, but was successfully completed with innovative solutions and speed.
“The completion of India’s longest rail tunnel between Devprayag and Janasu in Uttarakhand faced significant challenges, including moments when it seemed the tunnel might collapse and jeopardise the whole project,” Larsen & Toubro Limited (L&T) said on Saturday (April 26, 2025).
"The tunnel boring machine (TBM) named 'Shakti' was about five km inside the tunnel when it encountered a gush of water from all directions at the rate of around 1,500 litres per minute," Rakesh Arora, Project Director of the tunnel, told PTI.
Rishikesh-Karnaprayag rail link project: Vaishnaw witnesses breakthrough of longest rail tunnel in Uttarakhand
"Besides the TBM operator, there were 200 people inside the tunnel at that time. It was one of the toughest moments when the tunnel was at risk of flooding or collapsing. However, we took corrective measures immediately," he said.
Mr. Arora said the situation did not improve for around a month. “The team struggled to overcome it by using a combination of chemical as well as cement grouting to stabilise the rings and surrounding rock, consequent to which, the water flow started reducing and the engineers could stabilise the interiors successfully,” he added.
"Besides, there were occasions when huge pressure from the surrounding soft rock posed a serious risk to the tunnel's progress, which was successfully handled by speeding up the excavation works with a combination of lubricating the TBM shield using bentonite," Mr. Arora added.
The 14.57-km tunnel on the 125-km Rishikesh-Karnaprayag Rail Link Project achieved a breakthrough on April 16, 2025 in the presence of Railway Minister Ashwini Vaishnaw, Uttarakhand Chief Minister Pushkar Singh Dhami and other railway and State officials.