Atal Tunnel

Atal Tunnel (Hindi: अटल सुरंग) is a 9.02-kilometre-long (5.60 mi) road tunnel connecting Manali and Keylong. It helps in bypassing the Rohtang Pass, Himachal Pradesh in the eastern Pir Panjal range of the Himalayas. It carries two lanes of National Highway 3. It is the longest highway single-tube tunnel above 10,000 feet (3,048 m) in the world. It is named after the former Prime Minister of India, Atal Bihari Vajpayee.
The tunnel reduces the travel time and overall distance between Manali and Keylong on the way to Leh. The route, which previously went through Gramphu, was 116 km (72.1 mi) long and took 5 to 6 hours in good conditions. The new route via the tunnel brings down the total distance travelled to 71 km (44.1 mi) which can be covered in about 2 hours, a reduction of around 3 to 4 hours when compared to the earlier route. Moreover, the tunnel bypasses most of the sites that were prone to road blockades, avalanches, and traffic snarls.
The Moravian Mission first talked about the possibility of a tunnel through Rohtang Pass to reach Lahaul in 1860.
The proposal for the construction of a tunnel across Rohtang Pass was first conceived in 1942 by Dr. John Bicknell Auden, Geological Survey of India (GSI) who at that time visited this pass intending to divert the water of Chandra river to Beas.
When Atal Bihari Vajpayee became the Prime Minister, locals suggested his childhood friend Arjun Gopal, To visit him and to talk about Rohtang Tunnel. Gopal and two companions, Chhering Dorje and Abhay Chand, moved to Delhi. After a year of discussions, Vajpayee went to Lahaul in June 2000 and declared that the Rohtang Tunnel would be constructed. RITES conducted a feasibility study.
In 2000, the project was estimated to cost ₹500 crore and be completed in seven years. On 26 May 2002, the Border Roads Organisation (BRO), a tri-service organisation of the Defence Ministry specialising in road and bridge construction in difficult terrains, headed by Lt. Gen. Prakash Suri, PVSM, was put in charge of construction. The approach road to the tunnel entrance was inaugurated by Atal Bihari Vajpayee.
However the project did not move beyond the tree-felling stage by May 2003. By December 2004, the cost estimate had grown to ₹900 crore. In May 2007, the government of Dr. Manmohan Singh awarded the contract to SMEC (Snowy Mountains Engineering Corporation) International Private Limited, an Australian company, and the completion date was revised to 2014. However, there was no progress for the next three years, until May 2010.
Finally, the Cabinet Committee on Security in UPA government cleared the Rohtang Tunnel Project. The work was awarded to a joint venture of AFCONS Infrastructure Limited, an Indian construction company of Shapoorji Pallonji Group, and STRABAG AG, Austria, in September 2009. The drilling of the Rohtang Tunnel through the Himalayan ranges began on 28 June 2010 at the South Portal, 25 km (16 mi) north of Manali. Some of the anchoring and slope stabilisation work was subcontracted to Spar Geo Infra Pvt Ltd. Permanent maintenance free earthing system design, supply and installation was sub-contracted to Manav Energy Pvt. Ltd.
Prime Minister Narendra Modi renamed the tunnel as the Atal Tunnel, in honour of Shree Atal Bihari Vajpayee, on 25 December 2019, Vajpayee's birthday.
The Atal Tunnel has been planned to ensure an all-seasons, all-weather road route to strategically important areas of Ladakh and the remote Lahaul-Spiti valley. However, the tunnel will provide this connectivity only up to Darcha, north of Keylong in the Lahaul region of Himachal Pradesh. Connectivity to Ladakh will require more tunnels: either at Shikun La, or at the passes located on the present Leh-Manali road. Director General Border Roads Lt Gen Rajeev Chaudhry, VSM has initiated plans for construction of tunnel at Shinkula.
Total length of tunnel is 9.02 km.
The most challenging task was to continue the excavation during heavy snowfall in winter. Excavation for tunnelling was done from both ends. However, as Rohtang pass closes during the winter, the north portal was not accessible during winter and the excavation was being done only from the south portal in winters. Only about one-fourth of the entire tunnel was excavated from the north end and three-fourths was excavated from the south end. There were more than 46 avalanche sites on approaches to the tunnel.
Other challenges to the progress of the tunnel included difficulties in disposing of the more than 800,000 m of excavated rock and soil, heavy ingress of water (as much as 3,000,000 litres per day in June 2012) that required constant dewatering and costlier treatment, and unstable rocks that slowed blasting and digging. The progress of excavation was regularly slowed from 5 metres per day to just half a metre a day. A cloud-burst and flash flood on 8 August 2003 killed 42 labourers who were building the temporary access road. Questions were also raised on the impact of cutting down more than 700 trees on the ecology.
The tunnel is intended to create an all-weather route to Leh and Lahaul and Spiti valleys in Himachal Pradesh.
Salient features of the Atal Tunnel are as follows:
The following parameters have been set in design:
Project Cost : Approximately ₹3,200 crore
The tunnel was built using the New Austrian tunnelling method and has been equipped with a semi-transverse ventilation system, where large fans separately circulate air throughout the tunnel. A 2.250 m tall and 3.6 m wide emergency tunnel has been integrated into the tunnel cross-section beneath the main carriageway for evacuation during emergencies.
Fires inside the tunnel will be controlled within an area of 200 metres and fire hydrants are provided at specific locations throughout the tunnel. The tunnel also has a public announcement system to make important announcements in emergency situations for which loudspeakers are installed at regular intervals.
Heavy snowfall in the Rohtang Pass area is a major concern, especially on the approach roads to the main tunnel. To prevent any damage to the roads and to ensure the safety of the roads and tunnel users alike, avalanche control structures have been constructed. Since the Atal tunnel is likely to witness heavy traffic, CCTV cameras are placed at regular intervals in the tunnel which are connected to two monitoring rooms on both ends of the tunnel for vehicular management and pollution monitoring. Pollution sensors continuously monitor the air quality in the tunnel and if the air quality in the tunnel is below the desired level, fresh air is injected into the tunnel via two heavy duty fans on each side of the tunnel.