With the commissioning of the Chenani-Nashri tunnel in Jammu & Kashmir, India has to its credit the construction of Asia’s longest bidirectional road tunnel. In a much-awaited move, the central government inaugurated the tunnel on April 2, 2017, providing a safe, all-weather route to those travelling from Jammu and Udhampur to Ramban, Banihal and Srinagar. The landmark 9.28 km tunnel boasts of world-class safety features and a fully integrated tunnel control system that does not require any human intervention for operations, notably the first of its kind in India.
Making of the tunnel
Infrastructure Leasing & Financial Services Limited’s (IL&FS) transportation arm, IL&FS Transportation Network Limited (ITNL) was awarded the tunnel construction project by the National Highways Authority of India under Phase II of the National Highways Development Programme. The construction project has been undertaken on a design-build-finance-operate-transfer annuity basis for a period of 20 years, including an initial construction period of five years. ITNL will receive semi-annual annuities of Rs 3.17 million for the remaining concession period during which it will maintain the tunnel. The concessionaire had subcontracted the construction work to Jammu & Kashmir-based Beigh Construction Company Private Limited among others and a special purpose vehicle, Chenani-Nashri Tunnelway Limited, was incorporated for the project.
While the original cost estimate for construction was about Rs 25 billion, project delays led to an escalation resulting in a total cost of Rs 37 billion. As per reports, project deadlines were revised nine times and it took about five years for the tunnel to be completed. The primary reasons for the delays were disputes between construction workers and the executing agency, and bad weather conditions disrupting electricity supplies which hindered testing and inspection processes, among others.
Located at an altitude of 1,200 metres in the difficult Himalayan terrain, the tunnel is expected to reduce the distance travelled between Jammu and Srinagar from 41 km to 9.28 km. The successful launch of the tunnel is a result of the hard work of over 1,500 engineers, geologists, skilled workers and labourers who worked on the project, as well as the government that gave the required impetus to the project. Assistance was also given by a specialised team of tunnelling experts who were regularly called in for their advice, suggestions and guidance.
The tunnel is being lauded as a technological masterpiece. Nonetheless, like any other infrastructure project undertaken in the region, this one too was fraught with issues. “Working amidst young, immature Himalayan rocks and with the geological uncertainty of the Himalayan terrain was a huge challenge. A probabilistic approach and the New Austrian Tunnelling Method were used to overcome these issues,” says
J.S. Rathore, project director, Chenani-Nashri Tunnelway Limited. “Further, labour unrest was another factor that led to disruptions of over 150 days in project execution,” asserts Rathore.
Geological surprises such as the sudden ingress of water in the north portal towards Nashri and high temperature conditions inside the tunnel posed serious obstacles during construction. Besides, rock bursting and squeezing in the south portal due to low vertical and lateral cover zones were other hindrances.
“To add to the woes, there was poor road connectivity due to landslides, snowfall and traffic jams in the rainy and winter seasons during project execution, further hindering the work,” explains Rathore. “However, it is due to proper planning and execution, hard work and perseverance, learning from failures, and most of all, the love and excitement for what you are doing, that we have seen light at the end of the tunnel. We, the tunnel engineers, called it a dream come true,” he adds.
Automation all the way
The state-of-the-art, world-class technology used in the project has raised the bar for tunnel construction in the country. The tunnel comprises two lanes and 29 cross-passages, with a special lane for exigencies. Each tunnel tube has a diameter of 13 metres, while the sideway has a diameter of 6 metres. The use of automatic navigated boomers for drilling, a first in the country, resulted in a reduction in drilling time and ensured accuracy. Further, the traditional wire mesh construction system was replaced by the use of polyfibre/steel fibre shotcrete. This not only requires less labour and construction time, but also helps improve the crack capacity of the concrete. The use of Germany’s GHH 35 tonne capacity articulated trailers helped reduce the mucking time. Both the tunnels (the main tunnel and the escape tunnel) have been made 100 per cent waterproof, leaving no scope for water seepage from the ceilings or walls.
To keep pollution levels in check, a transverse ventilation system, enabled by ABB drives and controlled by ABB software, has been installed in the tunnel to provide fresh air to passengers. Besides, air quality monitors installed every 12 metres will help in ensuring appropriately low levels of carbon dioxide and carbon monoxide in the tunnel, preventing suffocation and ensuring an acceptable level of visibility, which is vital, especially given the length of the tunnel.
Further, in order to prevent a diminution of vision due to a change in the intensity of light while going in or coming out of the tunnel, lighting has been adjusted at a gradient of luminous strength. Besides, 6,000 LED multiple colour lights have been used to break the visual monotony. A three-tier power system has been used in the tunnel. While power for two of the tiers will be provided by switchyards at Chenani and Nashri, power for the third will be through a generator. Overall, the tunnel is expected to consume 10 MW power daily.
With regard to safety provisions, more than 100 CCTVs, one every 75 metres, have been installed in the tunnel. Parking spots have been designated for vehicles in the case of a breakdown and the speed limit has been set at 50 km per hour, resulting in a total tunnel drive time of 12-15 minutes. In case of a fire incident, the pushing of fresh air into the tunnel will be stopped and only longitudinal exhausts, which have been installed at regular intervals, will be operational. A fully computerised operations room for the surveillance of vehicles inside the twin tubes has also been established by ITNL.
Meanwhile, to deal with crisis situations, emergency messages will be communicated through the 92.7 FM radio channel. Keeping the radio on this channel has been made compulsory for vehicles travelling through the tunnel. Besides, GSM phones will also be operational inside the tunnel. In addition, 118 SOS boxes have been deployed, one every 150 metres on both sides, which will act as emergency hotlines for travellers in distress. The tunnel is also equipped with advanced scanners to ward off any security threat. Very few tunnels in the world have this kind of fully integrated tunnel control.
Weighing the costs and benefits
Owing to a reduction in the distance by around 30 km and travel time by about two hours, the tunnel is expected to result in daily fuel savings of Rs 2.7 million. The toll for light motor vehicles has been fixed at Rs 55 for a one-way trip and Rs 85 for a two-way journey. Meanwhile, a monthly pass of Rs 1,870 is also available. Further, mini buses will be charged Rs 90 for a one-way trip and Rs 135 for a two-way journey, while buses and trucks will have to pay Rs 190 for a one-way and Rs 285 for a two-way trip. Vehicles with a clearance height of over 5 metres have been prohibited from using the tunnel.
Leading by example
Several big-ticket tunnel projects in the country have been in limbo owing to similar constraints, such as the Zojila Pass tunnel project on National Highway-1D in Jammu & Kashmir. In this scenario, the inauguration of the Chenani-Nashri tunnel lends a ray of hope for the successful execution of projects of similar scope and size. Besides, the distinctive features of the Chenani-Nashri tunnel have also led to an expansion in the scope of tunnel projects in India. The expertise gained can be utilised to enable domestic developers to become self-sufficient in building tunnels, as replicating the modern technology features of this project in other upcoming and ongoing projects will now be easier and less time consuming. However, geological surprises – the biggest challenge for the sector – need to be dealt with. Besides, a lack of engineering skills, inadequate risk assessment, contractual disputes and lack of safety are other areas that demand attention.