A tunnel under Rohtang Pass is considered as a lifeline for Lahaul as when it will be completed, it will connect Lahaul with Manali in winter as well. Border Roads Organisation (BRO) in collaboration with Strabag-Afcons, a joint venture between India’s Afcons Infrastructure and Strabag SE of Austria is working hard to complete it as, but it got a little obstacle when a rivulet has sprung up during work in it.
Engineer said that a flow of 30 litres per second of the Seri rivulet is entering the tunnel and its volume can increase to 200 litres per second. The Seri is a tributary of the Beas river and flows down the mountain and the tunnel alignment is crossing beneath the rivulet. High water seepage may be encountered as digging work is move further.
To avoid such geological surprises, Engineers were taking various measures like rock grouting and bolting and using special chemicals to counter and pump out the flow. Over 350 BRO personnel and 24 experts from Germany and Austria have been working round the clock to meet the February 2015 deadline.
Of the 8.8-km horseshoe shaped tunnel, 2,700 meters from the south portal and 800 meters from the north portal have been excavated since work began in June 2010. The tunnel is located at altitudes ranging above 3,000 meters and lies beneath the snow covered Rohtang Pass. About 70 percent of the pass’ top remains under snow even during summer.
The average minimum temperature at the tunnel portal, while it is peak summer in the plains, ranges from five to seven degrees Celsius. The maximum is 17-18 degrees. The tunnel is projected to cost Rs.1,495-crore ($290 million).