Nearly 30 workers including those from China, Nepal, Uttar Pradesh, Tamil Nadu and Gujarat work around 12 hours a day in the underground tunnels

Kathiri has just begun and residents are already cribbing about the heat. But a small group of people may actually be looking forward to their time on the surface.

The rest of their day is spent 20 metres underground, carrying out vital work on the Metro Rail project.

Chang Zhu, a worker from eastern China, who is in his mid 20s, has been in Chennai for a few years now. “I am more or less used to the climate in the city but it is still a struggle to work inside the tunnel during summer with the high levels of humidity. A good ventilation system is in place; nonetheless the atmosphere is very different from ground levels,” he said.

Nearly 20-30 workers including those from China, Nepal, Uttar Pradesh, Tamil Nadu and Gujarat work around 12 hours a day in the underground tunnels in two shifts, said an official of Chennai Metro Rail Limited (CMRL).

“While there are no exhausts in place, we do have forced air circulation inside the tunnel and this provides for adequate ventilation. Also, we measure the temperature about 2-3 times a day and try maintaining it around 30-32 degree Celsius. Thus, while the temperature is lesser underground, the suffocation levels will definitely be higher since the air circulation is lower here,” said an official.

This is the first time 35-year-old Hiranyan is working in a tunnel. An electrical engineer from Chennai, he has had experience working with other private contractors before joining the Metro Rail project.

“The equipment we wear for safety before entering the tunnel — jackets, helmets and shoes — adds to the suffocation. It is really difficult to manage till about 3 p.m.; after that, it gets better,” he said.

Ram Kiran Lal, a native of Nepal, who is involved in the maintenance work inside a tunnel in a Metro site in Poonamallee High Road, also said that despite regular refreshments, work is truly a struggle.

“They give us mineral water or butter milk throughout the day. But sometimes, even that does not beat the heat,” he said.

(Names of workers have been changed to protect their identity).

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