Representative image.

Prime Minister Narendra Modi on Saturday inaugurated the strategic Atal highway tunnel, in the Himalayas, which will bring the infantry combat vehicles closer to the Line of Actual Control (LAC).

The tunnel, constructed by Border Roads Organization (BRO), is one of the world’s most challenging and a marvel of engineering motorways.

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Donning a BRO cap, Modi interacted with BRO director general Harpal Singh, who explained to him through a photo exhibition, about the hurdles the agency faced during the tunnel excavation.

Singh explained in detail the challenges encountered during the heavy water influx of Seri rivulet.

The 9.02 km-long horseshoe-shaped single-tube, two-lane tunnel — the world’s longest motorable tunnel at over 3,000 metre above the sea level, came up under the 3,978 metre Rohtang Pass in the Pir Panjal range some 30 km from here in Himachal Pradesh.

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Earlier, chief minister Jai Ram Thakur welcomed him along with defence minister Rajnath Singh and Union minister of state for finance Anurag Thakur upon his arrival at the SASE Helipad near here.

“The all-weather tunnel can take any military traffic, even armoured vehicles,” a BRO official said.

However, the all-weather road to forward areas of Ladakh requires more tunnels, either at Shikunla or at the high passes located on the 475-km Manali-Leh road for round-the-year connectivity.

Considered a wonder of human perseverance, the Rohtang tunnel, a dream of former Prime Minister Atal Bihari Vajpayee and named after him posthumously, was completed after 10 years of sheer hard work by the BRO with an outlay of Rs 3,200 crore.

Project Director Colonel Parikshit Mehra said a length of 587 m across the Seri-nullah or rivulet zone took them four years and the balance 8.4 km took almost the same time.

On the decision to keep the main and escape tunnel within the same opening was with a viewpoint not to disturb a large extent of rock mass and restrict excavation to a specific area only, Colonel Mehra said.

The tunnel construction, a blessing for the people of landlocked Lahaul-Spiti district who mark a new beginning in their lives this winter, was abandoned on numerous occasions, primarily due to the complex geology that included fracture zones and fault lines.

The tunnel will cut the distance between this Himachal Pradesh tourist resort and Keylong, the headquarters of Lahaul-Spiti, by 46 km, shortening the travel time by nearly three hours.

With the maximum speed limit of 80 km per hour, the tunnel is expected to see traffic of 3,000 cars and 1,500 trucks a day.

The tunnel has consumed 12,252 metric tonne steel, 1,69,426 metric tonne cement and 1,01,336 metric tonnes of concrete, and excavated out 5,05,264 metric tonnes of soil and rocks by adopting the latest Austrian tunnelling method for construction.

The construction contract of the tunnel has been awarded to Strabag-Afcons, a joint venture between India-based Afcons Infrastructure and Austria’s Strabag.

Chandigarh-based Snow and Avalanche Study Establishment (SASE) has designed mechanical structures to ensure the safety of motorists by countering avalanches on both ends of the tunnel that remain under snow even during peak summer.

The tunnel’s foundation stone was laid by United Progressive Alliance (UPA) Chairperson Sonia Gandhi on June 28, 2010, in the Solang Valley near Manali, some 570 km from the national capital.