National

Prime Minister Modi inaugurates Atal Tunnel - longest tunnel above 10000 ft

SimpliCity News Team · 04 Oct 2020

Ladakh: The Prime Minister inaugurated the Atal Tunnel yesterday and took the inaugural drive through in the 9km long tunnel.

The Atal Tunnel (also known as Rohtang Tunnel) is a highway tunnel built under the Rohtang Pass in the eastern Pir Panjal range of the Himalayas on the Leh-Manali Highway in Himachal Pradesh, India. At 9.02 km (5.6 mi) length, it is the longest tunnel above 10,000 feet (3,048 m) in the world and is named after former Indian Prime Minister Atal Bihari Vajpayee.

The tunnel reduced the distance between Manali and Leh by 46 km (28.6 mi) and reduced the travel time by 4 to 5 hours without any threat of road blockade or avalanche.

The usefulness of the tunnel may be better illustrated thus: The 117 km distance from Manali to the south of the pass to Keylong on the north side of Rohtang Pass via Gramphu 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 journey is much easier now as Manali to the South Portal of the tunnel is 24.4 kms ~ 50 mins, through the tunnel in approximately 15 mins and without traffic snarls, and North Portal to Keylong is 37 kms ~ 60 mins.

The tunnel is at an elevation of 3,100 metres (10,171 ft) whereas the Rohtang Pass is at an elevation of 3,978 metres (13,051 ft).

It was inaugurated by Prime Minister Narendra Modi on 3 October 2020. The Approximate cost of this project is 3200 crore.

The Moravian Mission first talked about the possibility of a tunnel through Rohtang Pass to reach Lahaul in 1960. Later, Prime Minister Nehru discussed a rope way to Rohtang Pass with local tribes. The tunnel project was conceived in 1983.

Almost 39 years after the first mention, when Atal Bihari Vajpayee became Prime Minister, locals suggested his childhood friend Arjun Gopal to visit him and 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 on June 2000 and declared that the Rohtang Tunnel would be constructed. RITES conducted a feasibility study.

In 2000, the project was estimated to cost ₹5 billion 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 ₹9 billion. In May 2007, the contract was awarded to SMEC (Snowy Mountains Engineering Corporation) International Private Limited, an Australian company by the Dr. Manmohan singh Government, and the completion date was revised to 2014. However, there was no progress for the next three years till May 2010.

Finally after much delay, 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, 30 km (19 mi) north of Manali. Some of the anchoring and slope stabilisation work was subcontracted to Spar Geo Infra Pvt Ltd.

Prime Minister Narendra Modi renamed the tunnel the Atal Tunnel, in honor of Atal Vajpayee, on 25 December 2019, Vajpayee's birthday.

The Rohtang 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 village north of Keylang in Lahaul region of Himachal Pradesh. Connectivity to Ladakh will require more tunnels: either at Shikunla, or at the passes located on the present Leh-Manali road.

Timeline

Total length of tunnel is 9.02 km.

The project was announced by then prime minister Atal Bihari Vajpayee on June 3, 2000. The work was entrusted to BRO on May 6, 2002.
The foundation stone of the project was laid on June 28, 2010 by Mrs Sonia Gandhi in her capacity as the Chairperson of National Advisory Council.
As of June 2012, two years after the start of the project, 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 at serri nullah fault zone, 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 of the tunnel collapsed towards the north portal on 17 October 2013 and the digging had to be stopped.
As of September 2014, 4.4 km of the tunnel, i.e., half of 8.8 km planned length had been dug.
As of December 2016, 7.6 km of the tunnel digging had been completed. Excavation was expected to be completed in 2017, with opening in the second half of 2019.
As of 3 Sep 2017, 276 meters of the tunnel digging work remained. Tunnel to be opened for emergency services like Ambulance to be opened by winters.
As on 13 October 2017 both ends of the tunnel met. The Defence Minister, Nirmala Sitharaman, visited the site on 15 October 2017.
As on 22 November 2017, it was decided to allow patients to be carried through the under-construction tunnel only in the gravest of emergency when the helicopter service was not available and not to allow civilians to enter the tunnel before completion due to risks of falling rocks, lack of oxygen in the tunnel as ventilation system was yet to be installed, etc. and likely interruption in construction work due to presence of civilians.
Sep 2018: the tunnel was used for evacuation of people stranded in Lahaul after sudden spell of bad weather blocked Rohtang La due to snowfall.
Jan 2019: 90% work completed.
Oct 2019: 100 meters work yet to be finished. To be opened for emergency traffic by Oct-2019 end. To be opened for general traffic by Sep-2020.
Nov 2019: Bus service trial started through the yet-incomplete tunnel on 17 November 2019. A Himachal Road Transport Corporation bus carrying 44 passengers entered tunnel from the south portal and the passengers alighted at the north portal. The bus service operated for next five winter months for residents of Lahaul and Spiti valleys. Private vehicles were not allowed through the tunnel.
Dec 2019: On 25th of December the tunnel, which was known as Rohtang tunnel till then, was officially renamed as the Atal Tunnel.
Sept 2020: 100% completion of project.
Oct 2020: The tunnel was inaugurated by Prime Minister Narendra Modi on 3 October 2020, in the presence of Minister of Defence, Rajnath Singh and Chief Minister of Himachal Pradesh, Jai Ram Thakur and Minister of State for Finance, Anurag Thakur.

Challenges

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 more than 800,000 m³ of excavated rock and soil, heavy ingress of water (as much as 3 million litres per day in June 2012) that required constant dewatering, costlier treatment and slowed the progress of excavation from 5-metre per day to just half a metre a day and unstable rocks that slowed blasting and digging. 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.

Specifications

The tunnel is intended to create an all-weather route to Leh and Lahaul and Spiti valleys in Himachal Pradesh.

Salient features of the proposed Rohtang Tunnel are as follows:

Length of Tunnel: 9.02 km (5.6 mi)

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

(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 ₹3,200 crore (Euro 370 million)

Safety measures

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.

Manav Engineering Group, a Banglore based Engineering firm, has provided the design and validation for electrical and instrumentation earthing to the tunnel. It is the same firm that has installed lightning protection atop the Burj Dubai tower.

Trivia

The 9.02 km (5.6 mi) long tunnel is the world's longest tunnel at an altitude above 3,000 m(10,000 ft). The nearest in comparison to the Rohtang Tunnel is the Anzob Tunnel in Tajikistan (length 5 km (3.1 mi), altitude 3,372 metres (11,063 ft)), 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.

After frequent visits of Director General Border Roads, officials from Defence Ministry and Himachal Chief Minister Jai Ram Thakur, August 31, 2020 was the deadline set to complete the remaining works in the tunnel. Started on June 28, 2010, the engineering marvel Atal Tunnel was inaugurated by PM Narendra Modi 3 October 2020.