Learning from the Rat-hole miners of India
India
heaved a sigh of relief when rescue workers brought out 41 trapped men on the 28th
of November 23. We owe a big thank-you to all agencies involved, led by
the National and State Disaster Management agencies. The last two days of the 17-day
rescue saga had some important lessons.
The
rescuers called in the army along with six rat-hole miners, who specialize in
working in confined and dangerous spaces. They succeeded where heavy, modern
machinery had failed. These were high performance auger machines that work like
giant corkscrews with a drilling head and a corkscrew mechanism to send the
debris back. They failed in Uttarkashi
where the tunnel under construction had collapsed. The machinery was to bore a
hole 80 to 90 cm in diameter. The plan was to insert steel pipes in the drilled
hole and bring out the trapped workers through them. The problem was that the
collapsed rubble had steel items like ladders and pipes buried in it. These
obstructions damaged the corkscrew like blades of the auger and made it stop.
However,
six rat-hole miners could drill through 10 meters of the rubble in 24 hours,
using only hand tools. The newspapers screamed that this was a case of men
succeeding where machines failed. I would argue that there is some other lesson
here for us.
Big augers
and cranes usually lack feedback. Imagine a man in a hurry trying to break down
a latched door using bare hands. He could fracture his hand. The rat-hole
miners could see and sense resistance from buried metal. They could call in
teams handling plasma metal cutters to cut the metal items into pieces that
could be removed. I believe that engineers should now incorporate computer
vision devices, strain gauges and even sound recognition capabilities into
heavy machinery like boring machines.
One possibility is to add a video-camera to the system so that the machine operator at the back could see the area being drilled and make intelligent decisions on how to proceed. A sound-processing subsystem could recognise sounds indicating problems and alert the operator.
Srinivasan
Ramani
29-11-2023
