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Connecting South Asia’s largest highway tunnel

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Connecting South Asia's largest highway tunnel

Equipping the Chenani-Nushri tunnel, located in the Lower Himalayas, with fail-safe communication technology and provisions for passenger safety.

Overview

Inaugrated on April 2, 2017 by our honourable Prime Minister Narendra Modi in Jammu and Kashmir, the Chenani-Nushri Tunnel is South Asia's longest highway tunnel.

Spanning 10.89 km, we equipped it with fail-safe communication technology and passenger safety provisions, to make it India's safest and longest bi-directional highway tunnel.

The Task

Located in the Himalayas, one of the most difficult terrains on the planet, the ‘Chenani-Nushri Tunnel’ is extremely important to India and the rest of Asia. Being India’s longest bi-directional road tunnel, it is integral to the various trade and transport routes that span across the country’s borders.

Our task was to equip this tunnel with telecommunication systems that were ultra-reliable, highly responsible, and most importantly, secure.  We had to ensure that in the event of an emergency, such as an accident or a landslide, provisions for emergency broadcasts as well as first-responder communications were set up. Furthermore, in order to ensure passenger safety, we needed to provide fail-safe measures for electrical and fire-related incidents.

The Challenge

When it comes to design for Acoustics and Radio waves within tunnels, they come with their own set of challenges. Working in these environments are usually the most challenging as it is difficult for achieving the required amounts of Speech Intelligibility, measured in STI (Speech Transmission Index), in order to establish flawless communication. This is due to loud volumes of noise from traffic, high reverberation, and echoing effects.

In order to overcome this, tunnel sections were first modelled in a virtual environment for acoustic analysis. These multiple sections were then combined side-to-side so as to simulate the entire length of the tunnel.

Next, a detailed design of the radio signal distribution was constructed, to achieve seamless radio coverage by Slot Broadband Radiating Cable, in order to match the specifications of the selected equipment. This was done to ensure that the solution worked right the first time.

During the construction phase, ongoing civil work inside the tunnel created a lot of dust and debris. This affected the termination of fibres at 29 LVR locations within the tunnel. Claustrophobic conditions posed great challenges to integration and installation.

The magnitude of this project demanded long working hours
inside the tunnel. As the timelines for commissioning grew stringent during civil works completion, installation and commissioning were done with multiple teams and in extreme temperatures during winter. Our partners worked hand-in-hand to meet the stringent requirements in both specifications and project
timelines.

The Solution

We did our part in making this tunnel safer and highly connected by deploying the following systems:

Evacuative Broadcast System – (Partner: BOSCH)

The EBS system ensures that emergency and safety-related messages are broadcasted in select areas and throughout the tunnel. There are 12 pre-recorded messages in three languages viz. Hindi, English, and Kashmiri. They are automatically triggered in the event of an emergency. Individual messages can also be relayed from the Control Room as well.

FM Rebroadcast System – (Partner: COBHAM)

Specifically deployed for passenger safety, it allows one to tune into FM channels while crossing the tunnel and also acts as an emergency broadcast system. During an emergency, the ongoing FM Station program can be interrupted, so as to alert passengers to take necessary precautionary measures.

GSM Repeater System (for cellular network coverage) – (Partner: COBHAM)

It facilitates mobile phone connectivity and ensures they are operative throughout the length of the tunnel, without being cut off from the outside world.

Wireless Communication System (WCS) – (Partners:
MOTOROLA for Radio and COBHAM for In-Tunnel
Equipment)

A critical means of communication for emergency first-responders, it is a direct voice link between the
scene of the incident and the Control Room. Handheld Radio communication (walkie talkies) and radios installed in emergency vehicles allow them to communicate with the Control Room and take necessary action during an emergency. It is also used in normal traffic conditions for voice communication.

The Highlights

  • Built at a cost of Rs 3,700 crore it will reduce the distance between Chenani and Nashri, from 41 km to just 10.9 km, bringing down the travel time between Jammu and Srinagar by 2 hours.
  • Over 1,500 engineers, geologists, skilled workers and labourers participated in the building of this tunnel. There are 124 CCTV cameras which allow the control room to monitor traffic.
  • Situated at an altitude of 1,200 metres, the tunnel has traffic and fire control systems, video surveillance, FM connectivity and transverse ventilation systems.
  • The main traffic tunnel is 13 metres in diameter and has a safety tunnel alongside which is 6 metres in diameter. The two tubes of the tunnel are internally connected through 29 cross passages (each after a gap of 300 metres) and the escape tunnel will be used exclusively by pedestrians.
  • The estimated value of daily fuel savings will be to the tune of Rs 27 lakh, according to the PMO.

The Benefits

Our systems, together with the fibre optic cable, laid across the length of the tunnel, forms the backbone that responds in real-time to any incident and ensures safe operations of the tunnel on a 24×7 basis.

These highly responsive and advanced systems were chosen because they met all the international standards of operation. They were proven to safely and efficiently operate in rugged environments while offering high availability. This made them ultra-reliable, secure, and provide value for money.