Subway Blues

Manoj Kumar’s smile belies the sleepless nights he has been having. For more than two years, the Border Roads Organisation (BRO) chief engineer and his team have been struggling to prevent water seeping in from Siri Nallah, a stream running over the Rohtang Tunnel they have been building. Estimated to cost Rs 17,000 crore, the tunnel underlies the Rohtang Pass and is expected to reduce the distance to Lahaul and Spiti in Himachal Pradesh by almost 78 km.

This is the first time globally that engineers are blasting and digging through a mountain at over 10,000 ft. Construction started in August 2010. But work received a major jolt last October, when a 30 m section of the 8.8 km tunnel caved in, courtesy the treacherous nallah. The project has already been delayed by almost two years, and the tunnel is now set to open for vehicular traffic in 2017-18.

“We conducted extensive surveys, but did not anticipate the extent of the inflow from the stream,” says Kumar, a career BRO employee. He has been consulting geologists, seismologists, and engineers from India and abroad to fix the seepage, but nature keeps pushing back. There is also a need for cheaper tools and tests. “The Tunnel Seismic Prediction test gives us an idea of the next 250 m. But each test costs Rs 25 lakh. We need cheaper but more effective tools,” says executive engineer R.S. Rao. Finance so far hasn’t been a constraint.

About 4.4 km of the tunnel has been dug, and work on the concrete lining, escape tunnel, and water and air ducts is on. “Work never stops, not even during winter, when there’s 20 ft. of snow,” says Krishna Kumar Sharma, officer-in-charge. The use of robotic arms to drill and to pump concrete has increased the pace of work, but progress is slow. At their peak, the 600 employees of Strabag-Afcons, the joint venture executing the construction, can dig 6 m a day.

When the project is completed, they would have excavated 1.5 million cubic metres of earth and rock. With an overlay of almost 2 km at one point and temperatures dipping to -20°C during winter, maintaining the tunnel will be as taxing as constructing it.

On completion, 4,500 vehicles will be allowed to pass through the tunnel in a day, and the armed forces will use it as an alternative to the Srinagar-Kargil-Leh route. But more critically, the tunnel will be a lifeline for the 32,000 residents of Lahaul and Spiti. For six to eight months a year, these areas are cut off from the rest of the country, save by air, weather permitting. The tunnel will also help local potato farmers, who are trying to grow and supply other vegetables nationally.