Rohtang tunnel engineers ready for geological adventure

Rohtang tunnel engineers ready for geological adventure

Indian and European engineers overseeing the progress of an ambitious project to dig a tunnel below the 3,978-metre Rohtang Pass in the Himalayas are bracing for a geological "adventure" - the torrential flow of the Seri river that could deluge the tunnel.

The 8.8-km Rohtang tunnel, an engineering marvel that is India's most strategically important infrastructure project, will ensure all-weather connectivity to Keylong in Himachal Pradesh's Lahaul and Spiti district. It is being built by the Border Roads Organisation (BRO) in collaboration with Strabag-Afcons, a joint venture between India's Afcons Infrastructure Ltd and Strabag SE of Austria.

"A geological challenge is approaching. We are feeling its affect," BRO Chief Engineer (Project Rohtang) P.K. Mahajan told IANS.

Stating that the Seri, a tributary of the Beas river, could flood into the tunnel, he added: "We are just about to cross the Seri, which is 200 metres above the tunnel passage. High water seepage may encounter as we move deep."

"For us it's just an engineering adventure". Officials added that the bed of the perennial Seri rivulet comprises mainly glacial deposits. There could be a possibility that the rivulet is very deep and the rock beneath is fractured.

According to studies, water flow in the Seri is up to 350 cubic metre per minute during the peak season of snow melting. Various measures are being adopted to counter the flow.

"We are adopting measures like rock grouting and bolting and using special chemicals to dry up patches of freshly exposed rock surfaces. We have a system to feel minute-by-minute pulse of the rock, how it's behaving (when it blasts) and what type of material the strata has. After meticulous planning, we are designing the techniques before proceeding ahead," Mahajan said. Since the Himalayas are young, more geological surprises are in store, he said.
"Since the area (where the work is going on) is known for hot water springs. We will not be surprised if we encounter hot water flows deep inside rock formations which could raise the temperatures (inside the tunnel) to over 70 degrees Celsius," Mahajan said.
Constantly working are larger blowers for cooling and pumping fresh air into the tunnel.Over 350 BRO men and 24 experts from Germany and Austria have been working day and night to excavate the tunnel despite continuous sub-zero conditions to meet the February 2015 deadline. Of the 8.8-km long horseshoe shaped tunnel - 1,880 m from the south portal and 755 m from the north portal - about 2.5 km has been dug since work commenced in June 2010.

The tunnel is located at altitudes ranging between 3,053 m and 3,080 m and is beneath the snow marooned Rohtang Pass. About 70 percent of the Rohtang Pass top remains under snow even during the peak summer.

Once ready, the tunnel  will be a boon for the cold deserts of Lahaul Valley, where over 20,000 people remain cut off from the rest of the country in winters owing to the closure of the Rohtang Pass.

Besides reducing road distance by approximately 46 km and saving travel time of about four hours, the tunnel will open up new vistas of trade and tourism and generate jobs for the locals. It has the capacity to ply 3,000 vehicles per day under any weather condition.

The Cabinet Committee on Security cleared the Rohtang tunnel project in September 2009. The foundation stone was laid by Congress president Sonia Gandhi June 28, 2010.