Uttarkashi tunnel rescue: What went wrong with the auger machine, what's next for rescuers?

The 41 men stuck inside the Uttarkashi tunnel might be out by Christmas, international tunnelling expert Arnold Dix has said. This setback came after an auger machine broke while drilling into the tunnel, thus blocking the passage and making the rescue operation more difficult.

In this context, let us have a look at what an auger machine is, how it broke down during the operation to rescue the trapped workers, and what is in store for the mission next.

Auger machine

A horizontal auger or boring machine is a tool used for digging horizontal bores (or tunnels) underground without causing any disturbance to the surface. The auger is a helical screw blade that is attached to a drill. When switched on, the drill pushes the auger through rocks, soil, or any such material. These machines are usually used in construction projects like laying cables or pipes.

In the ongoing rescue operation, the plan was to use excavators to remove debris blocking the tunnel. However, this plan did not bear fruit.

This was when the rescuers thought the auger machine would be the right instrument to use.

Why the auger machine did not work

At 2:30 pm on Friday, the machine was put back together and all of the augers were put back in after some difficulties over the previous days. By 4:30 pm, the auger was more than 45 meters inside when the push for the tenth pipeline began. An employee of the company that supplied the machine, Trenchless Engineer Services, stated that auger blades are available in three different lengths: eight, six, and three meters. Joints were used to connect many blades to one another over a distance of more than 45 meters.

There was a fresh impediment seen on Friday. In the past, when comparable circumstances arose, the machine and the auger blades were removed to allow someone to manually inspect the impediment inside the pipes.

The current approach

On the hills above the Silkyara Tunnel, authorities have also started vertical digging in an effort to provide a different path for the rescue of the trapped men.

The National Disaster Management Authority on Sunday said that work is on to retrieve broken parts of the auger machine and start manual digging while vertical drilling has also started to bring out 41 workers trapped for the last 14 days following the tunnel collapse in Uttarkashi.

National Disaster Management Authority (NDMA) Member Lt Gen (retd) Syed Ata Hasnain told reporters here that all efforts are going on to rescue the workers.

Considered as the second best option, the work on vertical drilling started around noon and 15 meters of drilling has already been completed, Hasnain said.

After 86 meters of vertical drilling, the crust of the tunnel will have to be broken to bring out the trapped workers, he added.

The member also mentioned that as many as six plans are being executed to rescue the workers but the best option so far is horizontal drilling, under which 47 meters of drilling has been completed.

Machines for undertaking sideways drilling (perpendicular drilling) are expected to reach the rescue site during night, Hasnain said.

(With PTI inputs)