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TBM breakthrough marks milestone for Himalayan rail project
07 August 2025
A second tunnel boring machine (TBM) has completed its drive near Rishikesh, India, marking a major milestone for the construction of a new 125km railway line between Rishikesh and Karnaprayag in the Indian Himalayas.
Image courtesy Herrenknecht
Contractor Larsen & Toubro (L&T) used two Herrenknecht Single Shield TBMs to excavate a 10.5km twin-tube tunnel through the complex phyllite rock of the Chandpur Formation.
The first TBM broke through in mid-April, and the second completed its drive in late June, according to a statement from Herrenknecht.
The machines, each with a diameter of 9.1m, were said to be specially designed to handle the unstable and water-sensitive phyllite rock. They featured torque box cylinders and Herrenknecht’s ISP geotechnical monitoring system, which allowed real-time adjustments and early detection of fault zones.
“This is the first time we’ve had this system on a machine in India,” said Sumit Gaur, Herrenknecht’s project manager. “It contributes to safety and a smooth drive, especially important given the geology here.”
The project, led by Indian government agency Rail Vikas Nigam Limited (RVNL), aims to cut the travel time between Rishikesh and Karnaprayag from seven hours to just over two, easing access for millions of Hindu pilgrims heading to the sacred Char Dham shrines. The route currently faces frequent delays from landslides and rockfalls.
L&T project director Rakesh Arora said Herrenknecht’s warehouse in nearby Dehradun helped ensure rapid delivery of spare parts, contributing to fast daily progress; up to 39m per day at peak.
“This project provides important references for future tunnelling in the Himalayas,” said L&T tunnel expert Chris Cooper, who noted the TBMs performed faster than conventional drill-and-blast methods.
Both TBMs are now fully underground, with the tunnel segments installed and breakthrough achieved, paving the way for future progress on what is considered one of India’s most ambitious rail infrastructure projects in mountainous terrain.
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