In April this year, Prime Minister Narendra Modi officially opened India’s longest road tunnel. Located in Jammu and Kashmir and spanning 9.28 Km, the Chennai-Nashri tunnel links the cities of Jammu and Srinagar, reducing the usual travel distance by 30 Km, and cutting the commute by two hours.
Road users can now enjoy a far quicker and easier passage than the traditional route through landslide and avalanche-prone mountain terrain. The tunnel also provides a far safer journey for its users and features a robust, reliable and future-proof public safety and cellular communications system.
India’s Safest Tunnel?
The National Highways Authority of India (NHAI) was committed to making the Chenani-Nashri tunnel the safest in India. As such, a number of innovative safety technologies were incorporated into the tunnel build, including 118 CCTV cameras, air quality and carbon-monoxide detectors, and an electrical fire signalling system. Ensuring reliable communication in the Chennai-Nashri tunnel was also essential.
The construction needed to include a system for both public safety and cellular comms which would guarantee mobile phone coverage for road users, as well as communication to and between emergency services teams. In addition to the 9.5 Km of primary road tunnel, the construction also includes a second tunnel which runs in parallel, for emergency escape use. The two tunnels are connected by 29.1km passages, at regular intervals of 300 meter. This meant that there was total of 19 Km of tunnel which needed to be effectively covered by the communications system.
Tricky Terrain
The tunnel passes through the lower Himalayas at an altitude of 12,000 meter. The mountainous surrounds, as well as the materials used for construction, prevent RF signal from passing into the tunnel, and therefore posed a problem for communications.
A communications system was required which could support GSM signals for commuters, as well as VHF and FM for public safety. Systems integrator Commtel Networks was tasked with establishing the critical communications infrastructure for the tunnel and for selecting and procuring the system. For this challenging project the system integrator required a partner with extensive experience deploying such systems in similar environments. And for this, it turned to Cobham Wireless. The decision, said Prasad Pai, head of technology solutions and engineering for Commtel Networks, was due to Cobham Wireless’ “highly reliable and state-of-the-art products.”
Solution for Safety
Cobham Wireless determined that a customised fibre optic distributed antenna system (DAS) would meet the project requirements and help guarantee the safety of tunnel users.
The company successfully deployed a fibre DAS which incorporates GSM cellular communications for use by the tunnel’s commuters, VHF for the operations staff and FM for emergency break-in announcements. The cellular solution utilises Cobham Wireless’ Active Point of Interface (A-POI), which channels the operator’s signal from the base stations positioned at the tunnel portal, to an optical master unit (OMU). Fibre optical cables are then used to distribute the signal to five multi-band repeaters which are positioned throughout the tunnel. This comprehensive system ensures that consistent coverage is available to commuters for the duration of their journey.
The NHAI spent Rs. 3,720 crore on the Chennai-Nashri tunnel and was committed to making it the safest in India. Achieving this status required the tunnel to feature a system which supports public safety communications between operational teams onsite as well as one-way communication to commuters using the tunnel.
Cobham Wireless’ solution has delivered on this. OMUs channel the signal to eight BSFs (band selective fibre optical repeater) and one D-CSR (digital channel selective remote) positioned throughout the tunnel, supporting VHF and FM technologies, and ensuring that communication is clear and reliable.
Those using the tunnel can also be confident that, in the case of an emergency, they will receive rapid and clear communication from rapid response teams. This is thanks to the break-in system which features in Cobham Wireless’ solution which allows emergency services teams to access the FM channel and alert drivers to potential safety issues.
Monumental Project
We are extremely proud of our involvement in such a monumental tunnel project and our success in delivering this solution in such a complex environment will open up further opportunities to deliver similar systems across the Asia Pacific Region.
The Cobham Wireless solution completes the Chennai-Nashri tunnel’s impressive range of integrated safety solutions. The provision of seamless, uninterrupted radio signal coverage means that commuters can stay connected throughout their journey, and operational staff can communicate reliably, both within and between departments.
The digital repeaters which feature as part of the solution are software-based, meaning new features and capabilities can be added and upgraded easily via a remote download. The system will remain up-to-date and future-proof, guaranteeing the safety of all the tunnel’s users for many years to come.
About the Author: Ajay Soni, Regional Manager, Cobham Wireless
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