Rescue efforts continued on the fifth day, with the American drilling machine opening a ‘tunnel within a tunnel’ to rescue 40 workers and engineers who had been trapped since 5 a.m. on November 12. Meanwhile, authorities are having a hard time reassuring the workers and their relatives and family members of the trapped workers, who have run out of patience after repeated unsuccessful rescue efforts. They believe not enough is being done and complain about endless waits for a machine.
Officials say an SOS has been sent to international experts, particularly Thailand and Norway, for “online advice”. The Indian Air Force on Wednesday airlifted a huge ‘American’ drilling machine in two parts, assembled them on the ground and took them to the crash site by road. Work on opening a new horizontal tunnel began on Thursday.
Here’s everything you need to know:
Tunnel 1 is part of the project to reduce the length between Uttarkashi and Yamunotri by 26 kilometres.
2. In the early hours of Sunday morning, part of the tunnel collapsed, trapping 40 workers and assistant engineers about 245 meters from the mouth.
The 40 men present come from 8 states of the country: Jharkhand (15) UP (8) Odisha (5) Bihar (4) West Bengal (3) Assam (2) Uttarakhand (2) Himachal (1)
3. Experts say that tunnels use either the ‘Drill and Blast’ method or ‘Tunnel Boring Machines’ (TBM), which costs a whopping Rs 200 million and is imported but safer.
4. Shallow tunnels of Delhi Metro were opened with TBMs.
5. However, TBMs cannot be used to tunnel in shorter mountains with an altitude of less than 500 meters. The DBM method of blasting rocks by drilling a hole is widely used in the Himalayan foothills.
6. They say that the accident may have occurred because a piece of loose rock was not noticed while the tunnel was being opened, or because water leakage weakened the rocks after the first part of the tunnel was completed.
7. There are machines like ‘Strain Gauges’ and ‘Deformation Gauges’ that geologists use to test the strength of rocks. Samples are also sent for review before starting the project.
8. Experts had warned that the ‘Char Dhaam’ project, aggressively promoted by the government, which involves widening of roads, tunneling and use of large and heavy machinery, requires more careful planning and execution to avoid disasters.
9. Geologically, the Himalaya is a young mountain range and is still changing. Former chief minister of the state Trivendra Singh Rawat had also warned the authorities against the tunnel construction.
10. Experts’ worst concerns appear to be coming true due to a lack of time and research prior to the start of construction. Experts also believe it is important to ensure that ‘independent’ experts are brought in to review projects and design reports. However, India does not allow international experts and geologists to examine projects in the Himalayas on national security grounds. However, it is a paradox that the help of the same experts is sought after accidents.
news source (www.nationalheraldindia.com)