Evaluation of Heat Stress in Construction Site of Metro Rail in Chennai.

Introduction: Tunnel boring machine (TBM) is used for constructing a tunnel. Worn out cutting tools have to be changed under difficult working conditions. Temperature is high and the work is strenuous. Work is often carried out under increased atmospheric pressure to ward off water ingress. Workers are at a very high risk.

Aim: To evaluate heat stress during hyperbaric intervention on TBM during Chennai Metro Rail construction.

Methodology: One hundred and eighty-eight miners after a thorough medical examination worked under increased atmospheric pressure for more than 45,000 man hours. Mitigating actions to protect workers by reducing temperature and increasing ventilation. Medical monitoring was done to identify and treat potential victims.

Results: 52° C was the highest temperature recorded. Most times work was carried out at a temperature range of 34-45° C.

Conclusions: Motivations of monetary gains, reduced working hours, and food supplements played a major role in work execution without any untoward incidence.