Larsen & Toubro (L&T) has achieved a significant milestone on the Rishikesh-Karnaprayag Rail Link project by setting a new world record in tunnel construction using a single-shield hard rock Tunnel Boring Machine (TBM). The feat was accomplished on June 29, a day ahead of schedule, when the TBM named 'Shiv' excavated 790 metres within 31 days during the final phase of tunnelling.This achievement marks the first time globally that a single-shield hard rock TBM has been used with such efficiency. The tunnel, which spans 13.09 km, runs parallel to a 14.57 km long upline tunnel that was completed earlier on April 16, 2025. Together, the twin tunnels between Devprayag and Janasu form the country’s longest transportation tunnels and are part of the 125-km-long Rishikesh-Karnaprayag Broad Gauge Rail Link Project in Uttarakhand, which is expected to become operational by December 2026.According to company officials, the combined length of both tunnels is 30 km, including the main tunnels, escape tunnels, cross-passages, and niches. Approximately 70 per cent of the work (21 km) was executed using TBMs, while the remaining 30 per cent (9 km) was completed through the drill-and-blast technique, also known as the New Austrian Tunnelling Method (NATM).The first TBM, named 'Shakti', completed 10.47 km of the upline tunnel 12 days ahead of schedule, while 'Shiv' completed 10.29 km of the downline tunnel a day ahead of schedule. On average, the monthly progress was over 400 metres using TBMs and over 70 metres using NATM.L&T executives praised the project's progress across both TBM and NATM segments, which allowed for the ahead-of-schedule completion of excavation work for India’s longest transportation tunnel. The project team overcame several geological and environmental challenges, such as loose rock formations, shear zones, high water ingress, and extreme heat and humidity in the long tunnels.Officials also highlighted the complex logistics involved in transporting and assembling the TBMs from port to the project site, handling tunnel segments and muck, and managing various tunnel-related activities. In addition to logistical hurdles, the project team faced challenges related to the mobilisation and retention of skilled personnel, securing quarry approvals, and managing stakeholder relations with customers, local communities, and authorities.The leadership acknowledged the crucial support and vision provided by Rail Vikas Nigam Limited (RVNL), which played an instrumental role in the successful execution of the project. News source: Deccan Herald