Can Horizontal Auger Boring Save Workers Trapped in Uttarkashi Tunnel in the Shortest Possible Time? – News18

The 41 workers trapped in the Uttarkashi tunnel are expected to be rescued in a minimum of two days if everything goes as per the plan. While as many as five options are being considered for the rescue, the fastest method on the agenda for saving lives is horizontal auger boring.

Considered one of the most common trenchless and tunnelling options, the machine is used to install pipes and casings in various ground conditions. It is cheaper and has minimum chances of soil collapse or damage to the surface.

The machine uses a combination of jacking to push pipe casings into the soil and an auger to remove the spoil from the inside of the casings as they progress through the bore. It has four main equipment components in a horizontal auger boring operation — the rotating cutting head, the auger, jacking equipment and entrance and exit pits.

It is well suited for softer ground conditions, but one of its limitations is that it will not pass through any hard surface. In case of a hard rock or metal in the passage, it will have to be dealt with manually.

Authorities believe that if there is no hard rock or no steel in the passage, the machine can complete the drilling in the next two-three days. However, each blockage could increase the rescue time by at least a few hours.

Explaining the process, a Ministry of Road Transport and Highways (MoRTH) official said a gas cutter will have to be used if there is metal in the passage. Hard rocks too will be removed only manually.

The machine needs to drill a passage up to 60 metres deep for 800 mm and 900 mm diameter pipes to create an escape path. The work is being carried out by the National Highways and Infrastructure Development Corporation Limited (NHIDCL).

Last week, the rescue work was hampered as the machine hit a metal object after successfully drilling 25 metres through the debris. The work stopped because there was a fear of further damage.

While the officials involved in the rescue are confident in the success of the method, they are still considering and working on other escape paths for saving the workers in case the auger boring does not work.