Rishikesh-Karnaprayag new Broad Gaugeraillink project

The project includes 12 new stations, 16 main tunnels, and 19 major bridges (including 5 key bridges), spanning across five districts of Uttarakhand: Dehradun, Tehri Garhwal, Pauri Garhwal, Rudraprayag, and Chamoli.

The project is of immense strategic importance, aiming to provide rail connectivity between Rishikesh and Karnaprayag. It facilitates access to key pilgrimage destinations, supports regional trade, uplifts underdeveloped regions, and enhances socio-economic prospects. The new rail line is expected to significantly cut travel time and cost, promote industrial and cottage industries, and boost the local economy and tourism sector.

Connectivity
The rail line links major towns such as Devprayag, Srinagar, Rudraprayag, Gauchar, and Karnaprayag.

Final Location Survey (FLS):

• Due to complex topography, FLS employed cutting-edge technology with support from international consultants, reputed institutes, and domain experts in tunnels, bridges, and railways.
• IIT-Roorkee was entrusted with the proof consultancy; the institute’s Director led the team.
• Advanced remote sensing techniques were utilized. High-resolution stereo satellite imagery (50 cm) from US WorldView-2 was used to generate a highly accurate (~2m) Digital Elevation Model (DEM), far superior to Google Earth, covering a 2.5 km corridor on both sides of the alignment.

Geological & Engineering Challenges:

• Himalayan geology poses complex challenges for rail construction due to rugged terrain, seismic activity, and variable geological conditions.
• A panel of renowned experts was appointed:
  • Mr. M. Ravindra, ex-Railway Board Chairman (Railways)
  • Dr. J. Golshar, Geoconsult Austria (Tunnels)
  • Dr. V.K. Raina (Bridges)

Salient Features:

• Total Length: 125.20 km
• Tunnels: 104 km (83% of alignment) across 16 main tunnels
• Open Cutting Embankments: 18.4 km (14.72%)
• Important Bridges: 3.07 km (2.21%)
• Total Tunnel Length: 213.57 km (104 km main, 97.72 km escape, 7.05 km cross passages)
• Longest Tunnel: 14.58 km
• Longest Bridge Span: Devprayag Bridge No. 6 (125 m)
• Tallest Bridge: Gauchar Bridge 15 (46.9 m)
• Srinagar Bridge No. 09: Longest overall at 0.5 km
• Gauge: 1,676 mm (BG), single line
• Electrification: Rigid Overhead Catenary (ROC)
• Ruling Gradient: 1 in 80 (C)
• Max Curvature: 2.750°
• Speed: 100 km/h (passenger), 65 km/h (freight)
• Station Yard Gradient Limit: 1 in 400
• Bridge Loading: 25T Standard (2008)
• Seismic Zone: Zone IV (entire alignment), site-specific spectrum considered

CURRENT STATUS OF THE PROJECT:

• Land: 100 % land was acquired before commencement of work. The details of forest, government and private land is as under:

Preparatory Works:

• Geological surveys (1:5000 scale), seismic and resistivity studies completed.
• Geotechnical Investigations: 164 boreholes, 15.6 km of drilling (up to 600 m depth).
• Hydrological and Seismic (MASW) studies by NIH and IIT Roorkee completed.
• Access roads and Adits tunnels constructed.

Commissioning Milestone:

• Virbhadra–Yog Nagari Rishikesh section (5.7 km) commissioned in March 2020.
• Maintenance infrastructure established.

Tunnel Construction:

• Tunnels distributed across 10 design packages. Design finalized; all tunneling initiated concurrently.
• Completed Tunnel Progress: 195 km (of 213 km total scope, including Adits and Cross Passages).
• Eight Adits completed in advance to facilitate multi-face excavation of long tunnels.

Bridge Works:

• Total: 19 major, 5 important, and 38 minor bridges.
• Important Bridges: 1 on Ganga, 1 on Chandrabhaga, and 3 on Alaknanda Rivers.
• ROB and RUB at Rishikesh completed.
• Major access bridges at Gauchar, Srinagar, and Sivai completed.
• Work on remaining 11 major/important bridges is progressing rapidly.

Targeted Milestones:

• Tunneling completion by Dec 2025.
• Track laying, electrification, OHE, and S&T work to commence thereafter.

Tunneling & TBM Tunnel T-08

• IR had only 125 km of tunnels until 2014; 468.08 km tunneled post-2014—a 3.7x increase.
• First successful TBM deployment in Himalayan geology.
• TBM (9.11 m diameter, single shield): 10.4 km completed. NATM: 4.11 km.
• Initial 600 m excavated by NATM for TBM launch from Portal 1; continuous NATM tunneling from Portal 2 (Janasu side).

Geological Overview:

1. Geological Setting:
   • Formation: Chandpur Formation, Jaunsar Group
   • Lithology: Schistose/Quartzitic Phyllite with Quartzite interbeds and veins
2. Rock Mass Conditions:
   • Jointed, foliated structures
   • Slight to moderate weathering; moderate rock strength
   • Highly variable rock mass characteristics along tunnel alignment
3. Investigations:
   • Challenging access; limited baseline data
   • Boreholes: Initial – 7 (1,196 m); Additional – 2 (1,077 m)
4. Overburden:
   • Max: 800 m; Min: 70 m
5. Tunnel Behaviour:
   • High squeezing potential under moderate to high overburden due to weak rock strata

Key TBM Challenges:

1. Geological Complexity:
   • Heterogeneous rock conditions: Poor to hard rock
   • 20% of alignment under squeezing ground, necessitating nonstop TBM operation
2. Operational Constraints:
   • Continuous TBM advance critical
   • Risk of entrapment in squeezing zones
   • Need for real-time adaptability to varied ground conditions
3. Water Ingress:
   • Significant inflows in two zones—up to 2000 lpm
   • Risk to TBM operation and personnel safety
4. Logistics & Site Access:
   • Material supply along 30 km highway impacted by monsoon, landslides, and pilgrimage season
   • Delivery reliability essential
5. Backfill Grouting:
   • 11 km grout pipeline; high maintenance
   • Varying geological conditions require adaptive mix designs
6. Parallel Construction Activities:
   • Cross passage works, TBM operations, and tunnel excavation underway simultaneously

Team Maverick