"Tunnelling In Himalayan Rocks Treacherous...": Expert Tells NDTV

On what could have caused the Uttarakhand tunnel collapse, Dr Sahu said there were several possible reasons, including defects in design or construction. "It could even be a freak accident."

In light of difficulties faced in the rescue of 41 workers trapped in an Uttarakhand tunnel since November 12, an expert from the Indian Institute of Technology in Delhi told NDTV of the need for guidelines to "correctly assess rock and sediment type before starting construction of a tunnel".

Dr Jagdish Telangrao Sahu, a member of a high-level government committee tasked with framing rules for the design, construction, and maintenance of tunnels, also stressed on the need for safety provisions, such as escape tunnels, at all stages of such projects, for both workers and end-users.

"Tunnel construction (provisions) in India is not so developed at this moment... earlier tunnelling was not used to this extent, as it has in the past 15-20 years. It used to be mostly for hydropower projects but now it is used for railway projects or for building highways," Dr Sahu explained.