|Location||Himachal Pradesh, India|
|Work begun||28 June 2010|
|Operator||Border Roads Organisation|
|Length||8.8 kilometres (5.5 mi)|
|Number of lanes||Two (one in each direction)|
|Operating speed||80 km/h (50 mph)|
|Width||10 metres (33 ft)|
Rohtang Tunnel is a tunnel being built under the Rohtang Pass in the eastern Pir Panjal range of the Himalayas on the Leh-Manali Highway. With 8.8 km (5.5 mi) length, the tunnel will be one of the longest road tunnel in India (the longest road tunnel in India will be the Chenani-Nashri Tunnel or Patnitop tunnel north of Udhampur) and is expected to reduce the distance between Manali and Keylong by about 60 km (37.3 mi) The tunnel is at 3,100 metres (10,171 ft) elevation whereas the Rohtang pass is at 3,978 metres (13,051 ft) elevation 51 km (32 mi) away from Manali. The pass receives heavy snowfall and blizzards during winter months and is open for road traffic for only four months in a year. Lying on the Manali-Leh axis, this is one of the two routes to Ladakh. The other route through the Zoji La pass on the Srinagar-Drass-Kargil-Leh highway also gets blocked by snow for nearly four months in a year. These two routes are vital to feed military supplies into the sub-sector west (facing Aksai Chin) and the Siachen Glacier.
Rohtang tunnel is not exactly under Rohtang pass; it is slightly west of the pass. The southern end (portal) of the tunnel is reached by turning left at Palchan, 10 km north of Manali on the way to Rohtang pass or about 40 km before Rohtang pass. After crossing Solang village, Dhundi is reached after 10 km. The south end of the tunnel is just north of Dhundi across the [[Bhaga River]Tributary of Chenab River ] at 32.3642° North and 77.1330° East coordinates.
The northern end of the tunnel meets the existing Manali-Leh highway near Teling village at 32.4388° North and 77.1642° East coordinates about 10 km west of Gramphu which is the first village after Rohtang Pass on the existing highway.
Rohtang tunnel was planned for ensuring an all-weather road route to strategically important areas of Ladakh and providing round-the-year connectivity to the remote Lahaul-Spiti valley. However, the construction of Rohtang tunnel will provide all-weather connectivity only to the Lahaul Valley of Himachal Pradesh up to Kyelang (Keylong). The all-weather road to Ladakh will require more tunnels: either at Shikunla, or at the passes located on the present Leh-Manali road for a year-round road connectivity to Ladakh.
The project was conceived in 1983 and announced by Prime Minister Atal Bihari Vajpayee on 3 June 2000. The project was estimated to cost Indian rupee INR 5 billion and be completed in seven years. On 6 May 2002, the Border Roads Organization was entrusted with the construction of the tunnel, and on 23 May 2002, the work was inaugurated by Mr. Vajpayee. The cost of the project was revised to INR13.35 billion, with an expected completion by 2010.
However the work did not progress much, with the project not moving beyond the tree-felling stage by May 2003. By December 2004, the project cost estimate had escalated to INR17 billion In May 2007, the contract was awarded to SMEC (Snowy Mountains Engineering Corporation) International Private Limited, an Australian company, and the completion date was revised to 2014. Despite multiple announcements that the work on the tunnel would begin in 2008, no progress had been made by November 2009.
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 after the Cabinet Committee on Security cleared the Rohtang Tunnel Project. The drilling of the Rohtang Tunnel through the Himalayan ranges began on 28 June 2010 at South Portal 30 km (19 mi) north of Manali.
Status of progress of the project
- As of January 2012, 2.5 km of the tunnel digging had been completed.
- As of June 2012, 3.5 km of the tunnel digging had been completed.
- Only a little progress was made in the next one year due to heavy ingress of water that required constant dewatering and slowed the digging and blasting to a crawl.
- As of October 2013, a little more than 4 km of the tunnel had been dug. However, about 30 m portion of the roof the tunnel collapsed towards the north portal on 17 October 2013 and the digging had to be stopped.
- As of March 2014, 4.1 km of the tunnel had been dug and the digging will be resumed when the snow melts in summer.
- September 2014: 4.4 km of the tunnel, i.e., half of 8.8 km planned length had been dug 
The Border Roads Organisation (BRO), a tri-service Defence Ministry agency specialising in road and bridge construction in difficult terrains, had estimated that the contractors are scheduled to complete the tunnelling work and get it ready for vehicle flow by 2015. However, the date of completion has now been put back by two years to 2017.
The most challenging task is to continue the excavation during heavy snowfall in winter. Excavation for tunnelling is being done from both ends. However, as Rohtang pass closes during the winter, the north portal is not accessible during winter and the excavation is being done only from the south portal during the winter. Only about one-fourth of the entire tunnel will be excavated from the north end and three-fourths will be excavated from the south end. There are more than 46 avalanche sites on approaches to the tunnel.
Other challenges to the progress of the tunnel include difficulties in disposing more than 800,000 m³ of excavated rock and soil and heavy ingress of water (as much as 3 million litres per day in June 2012) from unstable rocks that slows the blasting and digging, requires constant 24x7 dewatering and costlier treatment and slowed the progress of excavation from 5 metre 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. A feasibility study for the construction of a tunnel across Rohtang Pass was conducted by RITES.
Salient features of the proposed Rohtang Tunnel are as follows:
- Length of Tunnel: 8.8 km (5.5 mi)
- South portal coordinates:
- North portal coordinates:
- Shape (cross-section) of Tunnel: Horseshoe
- Finished width: 10.00 m (32.8 ft) at road level. (8m pavement and 1m footpath on both sides)
- General altitude of the tunnel: 3,000–3,100 m or 9,840–10,170 ft
- Designated vehicular speed: 80 km/h (50 mph)
- Geology of tunnelling media: Uniformly dipping alternate sequence of quartzites, quartzitic schists, quartz-diolite-schist with thin bands.
- Tunnel boring machines will not be used because of the inability to see inside the mountain, instead blasting and digging will be used to build the tunnel.
- Temperature variation in the area: 25–30 °C (77–86 °F) during May–June, −30 to −20 °C (−22 to −4 °F) during Dec–Jan.
- Overburden: Maximum 1,900 metres (6,230 ft), average more than 600 m (1,970 ft)
- Construction technique proposed: Drill & Blast with NATM
- Support system proposed: Fibre-reinforced concrete (100–300mm or 0–10 inch thick) combined with rock bolt (26.50mm dia, 5,000–9,000mm or 200–350 inch long) has been proposed as the principal support system. In areas of poor rock condition, yieldable steel ribs (ISMB 150/ISMB 300) have been proposed in addition.
- Tunnel ventilation: Semi-transverse system of ventilation has been proposed.
- A 2.25 m high and 3.6 m wide emergency tunnel will be integrated in the tunnel cross-section beneath the main carriageway.
The following parameters have been set in design:
- (a) Upper tolerance limit for concentration – 150ppm
- (b) Visibility factor – 0.009/m
- (c) Vehicles
- (i) Cars – 3000 Nos.
- (ii Trucks – 1500 Nos.
- (d) Peak hour traffic – 337.50 PCUs
- (e) Design vehicular speed in Tunnel
- (i) Maximum Speed – 80 km/h (50 mph)
- (ii) Minimum Speed – 30 km/h (19 mph)
Project Cost : Approximately Rs.(INR)17 billion (Euro 250 million)
A 2.25 m high and 3.6 m wide emergency tunnel will be integrated in the tunnel cross-section beneath the main carriageway for evacuation during emergencies.
The latest Austrian tunnelling method and ventilation system — semi transverse type considered as safest — will be adopted for this project. 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 are being constructed. The design for these structures is being provided by the Snow and Avalanche Study Establishment of DRDO.
As the Rohtang tunnel will witness heavy traffic, vehicular management and checking pollution is a priority. For this, CCTV cameras would be placed at a regular distance and will be further connected to two monitoring rooms on both ends of the tunnel. Sensors to check the pollution level will keep on updating the data and if the record is above the desired level, then quantity of fresh air injected inside the tunnel would be increased. Pollution level will be controlled within 90 seconds adding that two heavy duty fans each on both openings of the tunnel will be installed to inject fresh air inside.
The tunnel will have semi-transverse ventilation system, where large fans would separately circulate air throughout the tunnel length. Another safety feature being added is that fire inside the tunnel will be controlled within an area of 200 metres and fire hydrants will be provided on specific locations.
The tunnel will also have public announcement system to make important announcement in emergency situations for which loudspeakers will be installed at regular distances.
- When completed in 2016, the 8.8 km (5.5 mi) long tunnel is also set to become the world longest tunnel at an altitude above 3,000 m or 10,000 ft. The nearest in comparison to the Rohtang Tunnel would be the Anzob Tunnel in Tajikistan (length 5 km (3.1 mi), altitude 3,372 metres (11,063 ft)), Khojak Rail tunnel near Quetta in Pakistan (length 3.9 km, altitude 3,912m), Salang Tunnel in the Hindu Kush mountains in Afghanistan (length 2.6 km, altitude 3,400m) and the Eisenhower–Johnson Memorial Tunnel in the United States (length 2.73 km (1.7 mi), altitude 3,401 m (11,158 ft)).
- There were proposals of installing a Neutrino detector in the tunnel by Panjab University and Tata Institute of Fundamental Research
- The 85 km distance from Manali to Keylong on the other side of Rohtang Pass is usually covered by vehicles in about five to six hours, without counting the long hours of traffic jams on the hilly route. The same distance would now be covered in less than half-an-hour through the tunnel and without traffic snarls. Keylong would be just 25 km from the North Portal of the tunnel.
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