Rohtang Tunnel

Location: Manali, Himachal Pradesh, India
Route: Leh-Manali Highway
Length: 8.8 km
Client: BRO
Contractor: STRABAG-AFCONS JV

The Rohtang Pass Highway Tunnel is situated in the Western Himalaya region of Northern India. With its altitude of 3,980 m, it ranks among the highest trafficable passes in the world. It is located 51 km away from Manali and receives heavy snowfall and blizzards during winter for about four months. Rohtang Pass is intended to create an all-weather route to Leh and Lahaul & Spiti valleys in Himachal Pradesh. With an 8.8 km length at an altitude of 3,100 m, Rohtang Pass Highway Tunnel is the longest road tunnel in India at a high altitude.

Problem

The altitude, the extreme climate, as well as the geological conditions in the Himalayas were the challenges of this project. Within the tunnel area, rock comprised mainly schist and migmatite with expected disturbed zones and in some individual areas high squeezing the rock.

Solution offered

Encardio-rite was awarded an I&M sub-contract for complete monitoring solutions for the tunnelling works. Besides geotechnical monitoring during tunnelling, Encardio-rite also continuously conducted geophysical prediction by Tunnel Seismic Prediction System (TSP) ahead of tunnelling to enable early recognition of fault or fracture zones or zones where the rock mass characteristic changes. A geological prognosis was given that enabled the tunnel site management to determine necessary forthcoming tunnelling measures. Supply & installation of geotechnical sensors were provided along with tunnel seismic prediction, and weekly and monthly reporting with evaluation & interpretations. Multi-point extensometer, load cells, and Bi-reflective targets were used during the monitoring of the tunnel.