Tunnel it down

Image Source: Construction Week Online

 The 9-km-long Atal tunnel under the Pir Panjal range, named after former Prime

Minister Atal Bihari Vajpayee, will be the world’s longest highway tunnel above the altitude

of 10,000 feet (3000 metres). It was scheduled to be completed by May 2020, in a revised

estimate, but the Covid-19 pandemic pushed back the completion by a few months due to

lockdown conditions. Official sources said the tunnel had missed its February 2015 deadline

owing to tough geographical conditions in the Himalayas along with harsh climatic

conditions, besides a limited working season of six months in the tunnel's north portal and

missed it yet another time in 2019 and has finally been completed.

A feasibility study of the project Rohtang Tunnel was carried out in M

ay 1990 following

which the geological report was submitted in June 2004. This was followed by a design and

specification report which was prepared and finalized in December 2006. Border Roads

Organisation (BRO) officials say the project received final technical approval in 2003.

Following approval by Cabinet Committee on Security in 2005, tenders were floated in 2007

and the foundation stone was laid in July 2010 by UPA chairperson Sonia Gandhi. The

project was scheduled to be completed by February 2015 but it got delayed due to

unexpected problems.

It was originally designed to be 8.8 km long but GPS readings taken

on completion show it to be 9 km long.

The project was being built by the Border Roads Organisation (BRO), a wing of the Defense

Ministry, in collaboration with Afcons, a joint venture with Strabag AG.

Taming the glacial-fed Seri rivulet was a challenge for the engineers. It's a tributary of the

Beas river and the tunnel alignment is crossing beneath the rivulet. However, a geological

surprise in the form of a rivulet that sprung up in 2012 during the tunnel digging posed a

challenge. Its torrential inflow was emerging into the tunnel.

Once encountering the Seri rivulet's impact in 562 metre area. They have managed to

reduce its impact to just 30 metres by 2018 and had been working on controlling its seepage

thereafter. The construction teams faced fast flowing water from Seri Nullah, which flowed

on top of the tunnel route and impeded construction efforts. The sheer volume of water

prevented construction for several months while project engineers grappled with a way to

tackle the problem. The rock structures faced by the engineers too caused impediments.

The south portal of the tunnel had schist, migmatites and phyllite rocks while the north

portal had incoherently folded gneiss and biotite schist which were brittle and ductile in

nature which not only compromise the aesthetics of the tunnel but also would have been

instrumental in putting entire structure under the danger of a collapse.

The tunnel, whose both ends can be accessed after negotiating 20 landslide and snow

avalanche zones, is located at altitudes ranging above 3,000 metres and lies beneath the

snow covered Rohtang Pass, whose 70 per cent of the top remains under snow even during

summer.

The unique features of this tunnel begin a fair distance away from it on the approach roads

to the north and south portals. Bridges in rivers on the approach to the tunnel from both

the portals have also been completed and are now being painted. Snow galleries have also

been built at the approach road to the tunnel from Manali side, and this will ensure all-

weather connectivity.

Other features include an emergency escape tunnel under the main tunnel. This would

provide an emergency exit in case of any untoward incident which may render the main

tunnel unusable. The tunnel also provides a telephone every 150 metres, fire hydrant every

60 metres, emergency exit every 500 metres, turning cavern every 2.2 km, air quality

monitoring every one km, broadcasting system and automatic incident detection system

with CCTV cameras every 250 metres. BRO officials say vehicles will travel at a maximum

speed of 80 km per hour. Up to 1,500 trucks and 3,000 cars are expected to use it per day

when the situation gets to normal post Covid-19 restrictions. The strategic importance of

the Manali-Leh link was realized by the Indian government almost a decade ago

when Pakistan tried to cut off the Srinagar-Leh road during the Kargil conflict, in a bid to

restrict road access to Ladakh.

Currently, the movement of armed forces to the forward areas in Ladakh from Manali side,

which doesn't fall in the firing range of Pakistan forces, is feasible only from June to mid-

December.

The completion of the  Rohtang tunnel  is a key element in the Defence Ministry's attempts

to make the entire 475 km-long Manali-Keylong-Leh highway, used by the armed forces to

reach forward areas in Ladakh bordering China and Pakistan, motor able round the year,

said officials.

Cutting through the Pir Panjal range, the tunnel will reduce the distance between Manali

and Leh by 46 km. The Rohtang Pass, to which the tunnel provides an alternate, is located at

a height of 13,050 feet, and a journey from Manali Valley to Lahaul and Spiti Valley, which

normally takes around five hours to negotiate, would now be completed in little over ten

minutes.

While the tunnel will be a boon to the residents of the Lahaul and Spiti Valley who remain

cut off from the rest of the country in winters for nearly six months due to heavy snowfall,

the tunnel will provide almost all-weather connectivity to the troops stationed in Ladakh.

However, for full all-weather connectivity, additional tunnels will have to be built on the

Manali-Leh route so that the high passes on the axis do not impede movement due to

snowfall. A 13.2 km long tunnel will have to be built to negotiate the 16,040 feet high

Baralacha pass and another 14.78 km long tunnel will be required at the Lachung La pass at

16,800 feet. A third 7.32 km long tunnel will be required at Tanglang La pass at 17,480 feet.

This project has been welcomed by the people living in the addressed area as they have

dreaded the slow development and continued isolation due to unavoidable climatological

and topographical conditions.

NISHITA PATIL