December 10, 2014

Tunnels provide an effective method of linking hilly and other difficult areas, often curtailing journey time. The Indian road network does not have too many tunnels on date, but some of these constitute critical links of important highways in various parts of the country. Existing tunnels on roads and highways include the Jawahar Tunnel (2.6 km), a vital road link connecting Jammu with Kashmir, Bhatan Tunnel (1 km) on the Mumbai-Pune Expressway, and so on.

Several more tunnels are either planned or under various stages of construction in different parts of the country. The one under construction below the Rohtang Pass in the Leh-Manali Highway will be the longest (8.8 km) in India and the highest in the world, and would pass through the Eastern Pir Panjal range of the Himalayas.

Whether these tunnels reduce travel time between end points or are the preferred or only means of travelling between them, the adequate safety and security of travelers during transit is of paramount importance. The perceived security threats from natural and man-made causes may include:

 Blocked traffic
 from heavy snowfall outside (Jawahar tunnel faces this several time each year)
 from accidents or road damages (motorists come to know when they are already part of the blockage and cannot escape)
 from fallen stones or other material falling off the moving vehicles

 Lack of ventilation
 In shorter tunnels, the draft of air due to vehicle movement provides natural ventilation.
 In longer tunnels (typically more than 500 m), the air draft from moving vehicles becomes inadequate and additional means of forced ventilation becomes essential  Dark interiors
 most tunnels have little or no illumination in the interior and the motorists are dependent solely on their vehicle lights  In the event of vehicle light failure, the motorists are often required to move in pitch dark interiors

The modern day technology offers a range of solutions to mitigate these conditions, like -
 VIDS (Video Incident Detection System) – to detect incidents/blockages, etc.
 CCTV Cameras with infra-red capability to facilitate round-the-clock surveillance in tunnels
 VMS (Variable Message Sign) displays well ahead of the tunnel entry for advisories to motorists
 Dedicated communication facilities to enable users or maintenance teams to seek emergency assistance or to send SoS messages to Emergency Control Rooms

However there is no ONE SOLUTION THAT SUITS ALL – it must be customized to each specific location and site conditions.

Sudipto Chakarvaty

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