Tunnel ‘marvel’ below Rohtang Pass year away from opening

Vijay Mohan
Tribune News Service
Manali, October 24

Almost 6,000 feet below the snow-covered Rohtang Pass, the growl of a diesel engine amplifies and headlight beams bounce off the wet rock face in partial darkness as a heavy crane carefully labours through a water-filled depression next to large prefabricated concrete sections being put in place to construct an emergency escape channel on the 8.8-km-long main tunnel.

Alongside, helmeted workers attired in high-visibility fluorescent jackets and rubber boots move around nimbly, expertly manoeuvring construction equipment and power tools.

The tunnel, work on which was started by the Border Roads Organisation (BRO) in 2010, became partially motorable only recently.

Though civilian traffic is not permitted as yet, emergency vehicles are allowed to cross. It came into prominence last month when it was used to evacuate hundreds of people stranded in Lahaul region after heavy unseasonal snow. 

It will provide all-weather connectivity between Kullu valley and Lahaul and Spiti, which at present remains suspended for about six months due to snow. It is of immense strategic significance both for the military and civilians.

The Tribune team traversed the entire length of the tunnel to understand the mammoth task at hand and the significance of the tunnel which, at an average elevation of 10,000 feet, is the world’s longest. Crossing the Chandra river near Sissu over a makeshift Bailey bridge after descending the Rohtang, the approach to the tunnel’s north portal is covered with slush, with the season’s first snowfall adorning the surrounding hillside. Once inside the cavernous cavity that has been drilled into the mountain over the past about eight years, day or night doesn’t matter.

With dim lighting, support structures, equipment and vehicles dotting various places, driving has to be careful. Though large stretches having a concrete undersurface, on which a couple of layers of surfacing would be done later, permit a reasonably good speed, there are places where vehicles have to move over rough patches or pass through depressions and trenches often filled with water of slush.

The two-way road when complete would be 37 feet wide, but there are places at present where two vehicles can barely cross each other due to the ongoing construction.

At a couple of places, water continues to seep in. The Seri Nullah, a stream passing overhead that had given the BRO an immense headache and delayed the works by three-four years due to the heavy ingress of water is still not fully tackled. BRO officials hope to overcome the problem fully next year through modification of the tunnel’s structural design and use of specialised reinforced structures to channelise the flow of water.

The BRO expects to complete all works by December 2019. “Work will continue through the winters and we plan to finish construction activity by August-September next year and thereafter some time would be required for any rectifications or modifications that may be warranted,” Brig NM Chandarana, Chief Engineer, Rohtang Project, said.

About 3 km of the tunnel’s arch-lining and 4 km of the overhead ventilation system are still to be done. A two-storey building at each end of the tunnel that would house the ventilation systems are also yet to be built. A 110-metre stretch at the north portal is being realigned to mitigate avalanche threat and align the tunnel’s end with a concrete bridge coming up over the Chandra that would connect it with the Manali-Leh highway. Realignment would do away with a turn along the hillside to reach the bridge.

6,000 ft beneath Rohtang pass

46 km travel distance to be reduced between Manali and Leh (4 hours less travel time)
1983 Tunnel idea first floated, but the work on it finally started in 2010
2015  Original deadline for tunnel completion, but changed to Dec 2019
10,000 ft Height in Manali at which tunnel’s mouth towards Leh opens
8.8 km Its length — will be the world’s longest tunnel at this altitude