Chenani-Nashri Tunnel — An Engineering Marvel

Chenani-Nashri TunnelThe Chenani-Nashri tunnel is a single-tube bi-directional tunnel, with a 9.35-metre carriageway, vertical clearance of 5 metres, and a parallel escape tunnel with cross passages connecting to the main tunnel.

The 9.00 km Chenani-Nashri tunnel, India’s longest and safest tunnel, built in a record period of five years, will reduce travel time between Jammu and Srinagar by at least two hours. It was recently inaugurated by PM Narendra Modi, and opened for traffic.

Built at a cost of Rs.3,720 crore on the BoT annuity model, the tunnel is a part of the Jammu-Srinagar Highway’s four-laning project. Constructed between Udhampur and Ramban at an elevation of 1,200 metres on one of the most difficult terrains of the Himalayas, this all-weather route is not only India’s longest road tunnel but is also Asia’s longest bi-directional highway tunnel. A unique feature is that it is a single-tube bi-directional tunnel, with a 9.35-metre carriageway, and a vertical clearance of 5 metres. There is also a parallel escape tunnel, with cross passages connecting to the main tunnel at intervals of 300 metres.

The project is believed to have been conceived in early 2009 followed by the bidding process, and by 2010, the project was finally awarded. Though work on the project was scheduled to begin from December 2010, construction started only in May 2011. Despite all the odds such as political disturbances in J&K and the region’s harsh weather conditions, the project was successfully completed this year, that is, in five years and nine months’ time. The construction work was executed by IL&FS Transportation Networks Limited and was closely monitored by the Ministry of Road, Transport and Highways (MoRTH).

Part of the 293-km long four-laning of the Jammu-Srinagar National Highway, the Chenani-Nashri tunnel, built with New Austrian Tunnelling Method (NATM) has a series of smart safety features -- all functioning / monitoring through a single software. Features include an Integrated Traffic Control System; Surveillance, Ventilation and Broadcast System; Fire Fighting System, Evacuation Broadcast System; and an emergency SOS box at every 150 metres. In case of any help, the tunnel users can inform the cotrol room through the SOS call Boxes. At the same time the incident detection system will immediately raise and alarm at control center.

The Chenani-Nashri project has set a benchmark for all other construction firms in India. Its successful completion has not just paved the way for other construction firms to use the technology, but also raised the standard of infrastructure building in the country. The National Highways and Infrastructure Development Corporation Ltd (NHIDCL) has decided to replicate the technology for the upcoming 14 km Zoji la tunnel between Leh and Srinagar.

Work on the other 12 tunnel projects (also part of Jammu-Srinagar Highway’s four-laning project) is in full swing. Once constructed, these will reduce the length of the 293 km between Jammu and Srinagar by 62 km, and the distance of 231 km will be covered in 4-4.5 hours. The 293-km-long four-laning of the Jammu-Srinagar National Highway project, expected to be completed by 2019, is seen as the lifeline of the State.

"The Chenani-Nashri Tunnel is going to be an economic game changer," says Mr. Ashutosh Chandwar, VP&RH North, IL&FS Transportation Networks Limited, in an interview with S.A.Faridi & Maria R.

Ashutosh Chandwar
At the outset, please accept our heartiest congratulations on successfully completing the challenging Chenani-Nashri tunnel project. Please share your experience on this critical but strategically important project.

I convey on behalf of IL&FS Transportation Networks Limited, my thanks to you and all those who have supported us directly and indirectly in successfully completing the Chenani – Nashri Tunnel (CNT). CNT is the country’s first and the world’s sixth tunnel with a transverse ventilation system and having bi-directional traffic. The 9 km tunnel is also not only India’s longest highway tunnel but also the longest in South East Asia region. While for many it might just be another structure, but for us and the team of people involved from conceptualization, designing, constructing and bringing it to life, it’s been a challenging task to construct a tunnel running through the Himalayas.

But its greatness lies not so much in its length as it does in the fact that this is a technological marvel. Not only has it been built on a treacherous terrain, cutting through snow-clad mountains, but it has also used cutting-edge technology. The challenge was to inculcate technology in excavating the tunnel with so much of overburden (up to 1100 m) and arranging logistics in the region. Probably, it’s largest highway project undertaken in the country.

Chennai Nashri Tunnel

What are the unique features of the project?

The 9.0 km tunnel, will bypass the snow and landslide prone Kud, Patnitop and Batote on the Jammu-Srinagar national highway. The tunnel’s environment-friendly design provides for a safe and all-weather route, with time saving of two hours for motorists travelling along the highway between Jammu and Srinagar, which is prone to frequent and long traffic jams due to landslides, snow and sharp curves, breakdown of vehicles and accidents, seen on mountainous routes. The reduced travel time will result in a saving of fuel worth Rs 27 lakh per day on traffic projections.

A unique feature of the tunnel is that it is completely dry, with not a single drop of water throughout the entire length of the tunnel. This has been done by using water proofing membranes behind the concrete walls. A system behind the membrane collects the water coming down from the mountains and takes it to a central drain. The collected water is then saved for captive use such as for firefighting and construction activities.

What were the challenges during the development process?

To overcome the varied challenges, including the ones mentioned above, we brought our various strengths to the fore such as our ability to mobilize working capital for the project in times of high cost of borrowings. This ensured smooth running of the construction and completion of the project. The contractor appointed had left the project midway, whereafter we negotiated, mobilized and managed the work with small sub-contractors. To carry out the work was a critical factor in maintaining the required pace of progress. IL&FS Transportation’s managerial strength in making financial, procurement, engineering, execution and trust of our lenders and investors helped us to make this happen.

Our project management strategy was “strategy without tactics is the slowest route to victory; tactics without strategy is the noise before defeat”, so we expect the best, plan for the worst, and prepare to be surprised. It was necessary to inculcate ownership in every worker engaged in the project.

Indias longest highways tunnelPrime Minister Narendra Modi dedicated India’s longest highways tunnel – the Chenani-Nashri tunnel in Jammu and Kashmir to the nation on 2nd April 2017. On this Occasion, the PM also announced to invest around Rs. 7,000 crore in highways projects in Jammu and Kashmir in the next two years.

For engineers, tunneling in hilly areas means dealing with difficult terrain conditions, in-situ stresses, ingress of water and gases, geothermal gradient, high-level of seismicity, etc. What advanced mechanization and tunneling technologies were used on such a challenging site to complete the project safely and smoothly?

Some of the main difficulties we faced were the unpredictable nature of Himalayan geology. The wide variation in its rock classes caused frequent over-breaks, and also caused convergence, settlement, tilt, etc, in the surrounding rocks to overshoot estimates. The rock mass took longer than expected to minimize its settlement, and thus, further works were put off. This also made us expend additional effort and time on our support systems and on additional monitoring of excavation. We also encountered aquifers (water bearing rocks) during linear excavation and this caused seepage during the excavation, which led to further delays in the progress.

With parallel excavation from both the north as well as the south portals, we were able to achieve a certain rate of progress whenever we encountered such strata from any one side. Also, we undertook excavation of the Escape Tunnel far ahead of the Main Tunnel, so that we could get an approximate of the nature of the rock mass likely to be encountered while excavating the Main Tunnel. In NATM (New Austrian Tunneling Method), the precision of blast, early clearance of excavated material, quick installation of support system, continuous monitoring, and remedial measures for convergence, is key. We deployed navigated drilling boomers specific to our requirements. We used articulated low bed dumpers and high capacity loaders for quick disposal of muck. We mobilized special hydraulically operated gantry forms for lining activities in the tunnel, which made the final lining with precision and remarkable finish.

Since 2014, there were days of intense flooding due to unrelenting rains. This caused widespread damage to NH 1A leading to the tunnel, and landslides. This caused delays in the transportation of construction materials to our site location. Our mitigation was by using our stockpiles and helping the authorities in clearing the landslide to open up the blocked highway in the least possible time.

Chennai Nashri Tunnel work

CNT has been dubbed the ‘safest highway tunnel in the country’. Please elaborate.

CNT, the world’s sixth road tunnel, has a transverse ventilation system enabled and controlled by ITCS. It also boasts features like Video Surveillance System, FM Rebroadcast System, Entrance Detection Control System and Firefighting System. All systems are controlled / monitored using the Integrated Tunnel Control System (ITCS) for safe and smooth travel. There are 124 closed-circuit TV cameras for surveillance inside the tunnel. In case of a traffic violation, the control room will inform the traffic police deployed outside the tunnel, who will fine the violators on the spot. There is also an intelligent traffic mechanism with a fully automatic smart control, almost without human intervention, for its operations.

Even though the tunnel is very long, you need to have no worries about your mobile phone connectivity as providers like Airtel, BSNL and Idea have set up their network facility. So, you can easily get connected with anybody outside the tunnel. The 29 cross passages between the two tunnels will be used to evacuate a user who might be in distress, or to tow away a vehicle that might have broken down. The 124 cameras and a linear heat detection system inside the tunnel will alert the ITCS located outside to monitor and intervene, if necessary.

What is the total project cost, and was there any cost overrun due to unexpected conditions?

The total cost of the project is Rs.37200 million, of which 80% is funded by debt and the remaining through our internal sources - Equity and Sub Debt. Primarily, cost overrun was due to the high interest rate during 2011-15.

Chennai Nashri Tunnel work

As part of the Jammu-Srinagar Highway’s four-laning project, how is the CNT going to be a game changer for the economy of J&K?

CNT is not just the longest tunnel, but a big leap for Jammu and Kashmir in terms of development, and will act as an engine of growth and employment for the people of the region. It will provide safe and all-weather route that will result in significant time savings to motorists travelling along NH1 between Jammu and Srinagar, which is prone to frequent and long periods of traffic jams. CNT will reduce the total distance between Chenani and Nashri by 30 km and travel time by approx two hours, with resultant saving on fuel to the tune of Rs.27 lakh per day. Overall, CNT will ensure preservation of the pristine forest in the ecologically sensitive Patnitop area, and will provide for better integration of Jammu, not only with people of the Kashmir valley, but also with Kishtwar, Doda and Bhadarwah, by providing better connectivity with reduced and safe travel. The tunnel will also boost economic activities and tourism in J & K State.

In addition to the above, movement of goods will also get a push due to the reduced travel time, and this can lead to an increase in business revenue. Additionally, essential supplies and relief measures in the hilly state can be transported more swiftly through this tunnel. “The tunnel will bolster tourism in the state” is the message India has given to the world.

Chennai Nashri Tunnel work10 GHH low height Dump Truck (Model MKA35) played a key role in taking out the muck from the Tunnel

CNT will also have a very positive impact on the state’s economy. The project provided employment to over 2000 unskilled and skilled youth of Jammu and Kashmir as 94% of the work force was from the state itself. This tunnel will result in job creation, the state’s hotels, motels, and related businesses will get a boost, and all this will create new job opportunities for the unemployed youths of Kashmir.

Importantly, the success of this project will revolutionize the highway sector, and planners will have more confidence and will come out with more and more new highway tunnel projects. We are already receiving enquires from the authorities for managing and maintaining highways using the ITCS deployed in the tunnel. We will definitely witness a sea change in the operation of highways in India.

Facts & Figures
  • India’s All-weather tunnel located at 1200 metres, thrice the height of Empire State Building.
  • Built at a cost of Rs.3,720 crore, the tunnel will reduce the distance between Jammu and Srinagar from 41 km to 9.00 km
  • Rs.27 Lakh fuel savings a day
  • The Project was awarded to ITNL by the National Highways Authority of India (NHAI)
  • 1,500 engineers, geologists, skilled workers and labourers worked on the project. The project has provided employment to about 2000 unskilled, semiskilled and skilled youth of J&K.
  • 92.7 FM is mandatory for vehicles where emergency messages will be relayed
  • 6,000 LED multiple colour lights used
  • GSM phones will work inside the tunnel. 118 SOS boxes have been set up, one every 150 metres on both sides
  • Smoke and heat dampers will react quickly in fire incidents
  • 124 CCTVs, one every 75 metres
  • 19 km long excavation was done for main tunnel, escape tunnel and cross passage. The excavation was possible by adopting the New Austrian Tunnelling Method (NATM).
  • Comprises two tubes and 29 cross-passages, with special lane for exigencies
  • Main tube has a diameter of 13 metres, while escape has a diameter of 6 metres
  • Air quality monitors every 600 metres will keep a check on carbon monoxide + opacity
  • Automated Integrated Traffic Control System will monitor traffic round-the-clock and overheated vehicle will be made to stop for cooling off outside the tunnel
  • This is India’s first tunnel with transverse ventilation system
  • Equipment & machinery: Boomers, Concrete Sprayers, High Capacity Articulated Dumpers, Hydraulic Gantries, Pumps, indigenously developed concrete batching plants, gantry forms, travellers, dumpers, transit mixers, concrete pumps etc..
  • Construction materials used: approx 2 lacks MT of cement, 25000 MT of Steel, 5000 MT of Explosive for excavation works.
  • Integrated Tunnel Control System to control/monitor traffic control system, communication system, power supply system, tunnel ventilation system, tunnel lighting system, Emergency call boxes, and fire fighting system.

NBM&CW May 2017

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