India’s Longest Transport Tunnel: A historic milestone was achieved today with the successful tunnel breakthrough ceremony of Tunnel No. 8, the longest transport tunnel in India, as part of the Rishikesh–Karnaprayag Railway Project. The ceremony was graced by Union Minister for Railways, IT & MeitY Shri Ashwini Vaishnaw, Chief Minister of Uttarakhand, and Local MP Shri Anil Baluni.
Tunnel No. 8, stretching 14.58 km, has officially surpassed the 12.75 km rail tunnel between Khari and Sumber in the USBRL project and the 9.02 km Atal Tunnel on the Manali–Leh highway, making it the longest transport tunnel in the country.
Project Highlights:
- Total Project Length: 125.20 km
- Tunnel Coverage: 83% (104 km main tunnel length)
- Total Tunnel Length (Main + Escape + Cross Passages): 213.57 km
- Number of Tunnels: 16 main tunnels, 12 escape tunnels, and multiple cross passages
- Station Count: 12
- Major Bridges: 19 (including over Ganga, Chandrabhaga & Alaknanda rivers)
- Construction Packages: Tunnels divided into 10 packages; all tunneling initiated simultaneously
Engineering Feat: TBM in Himalayan Terrain
- Tunnel T-08 marks the first successful use of Tunnel Boring Machine (TBM) in the Himalayan geological terrain by Indian Railways:
- TBM Specifications: Single shield with 9.11-meter excavation diameter
- Excavation Progress: 10.4 km by TBM; 4.11 km by NATM
- Launch Setup: First 600 meters excavated using NATM to launch TBM
This achievement significantly contributes to India’s overall tunnel construction progress. Since 2014, Indian Railways has added 468.08 km of tunnel length, compared to 125 km till 2014 — nearly a 3.7-fold increase.
Geological and Operational Challenges:
- Rock Formation: Chandpur Formation of Jaunsar Group
- Conditions: Closely jointed, moderately weathered, weak to moderately strong rock mass
- Overburden: Up to 800 meters
- Tunnel Behavior: Severe squeezing anticipated in approx. 20% of alignment
- Water Ingress: Two major zones recorded inflows up to 2000 liters per minute
- Logistics Hurdles: Material transport along a 30-km stretch amid monsoon, landslides, and Yatra traffic
- Grouting System: 11 km grout pipeline with custom mix requirements
Bridges and Connectivity Infrastructure:
- 19 Major Bridges (8 completed)
- 3 Important Bridges (completed: 1 on Chandrabhaga, 2 on Alaknanda)
- 1 ROB and 1 RUB over NH/SH at Rishikesh
- 3 Major Road Bridges for construction access completed at Gauchar, Srinagar & Sivai
Commissioning & Future Targets:
- Virbhadra–Yog Nagari Rishikesh section: Commissioned on March 20, 2020
- Full tunneling works are scheduled for completion by FY 2026–27
- Track laying, OHE, Electrical & S&T works to commence shortly
Significance:
The Rishikesh–Karnaprayag rail line is a critical connectivity project in the Himalayas, aiming to bring all-weather rail access to the Char Dham region, enhance tourism, and support strategic mobility. The successful breakthrough of Tunnel No. 8 underscores India\’s growing prowess in complex infrastructure development and tunnel engineering.
