Chennai-Nashri Tunnel is inaugurated on 2 April 2017 by Prime minister of India and is India’s longest road tunnel with a length of 9.28 km (5.8 mi). It is a two-lane tunnel which has two tubes running parallel to each other its work started in 2011 and was scheduled to be completed in 2016 but work got extended and completion scheduled could be possible only in April 2017.
The two tubes are 6 m in diameter and are connected by 29 cross passages at regular interval of every 300 meters. There are several exhaust meters along the tunnel which will check no excessive carbon-dioxide build up inside. With inlets, every 8 meters, bringing fresh air into the main tube, and exhaust outlets every 100 m opening into the escape tube, the tunnel is the country’s first — and the world’s sixth — road tunnel with a transverse ventilation system.
The 29 cross passages can be used between the two tunnels during any emergency need. It is India s first tunnel with a fully integrated tunnel control system. There are total 124 cameras and a heat detection system inside the tunnel which will alert the Integrated Tunnel Control Room (ITCR) located outside the tunnel to the need for intervention.
SOS boxes installed every 150 m will act as emergency hotlines for commuters in distress. The tunnel is located at an altitude of nearly 4,000 feet in difficult Himalayan terrain. Despite having been excavated in such geographic conditions, both tubes are completely waterproof.
This two-lane tunnel has reduced the distance between Jammu and Srinagar by 30.11 km and total time saved is 2 hours. Also, the distance between Chennai and Nashri will be reduced to 9.2 km from 41 km.
The all-weather tunnel bypasses snowfall and avalanche prone areas in winter at places like Patnitop, Kud, and Batote that obstruct NH 44 every winter and cause long queues of vehicles – sometimes for days at length. It is one of the most advanced road tunnel built in the country becomes the longest Highway tunnels in Asia.