This standard lays down the safety requirements and precautions to be taken during tunnelling operations in rock. It covers critical hazardous activities including drilling, blasting, mucking, ventilation, illumination, and scaling to ensure the occupational health and safety of underground workers.
Lays down safety requirements for tunnelling operations specifically in rock, covering excavation, support, and ventilation.
Quick Reference Values
lighting circuit voltageNot exceeding 110V for general tunnel lighting
portable lighting voltageNot exceeding 24V in wet underground areas
vehicle clearanceMinimum 600 mm safe clearance for moving equipment
ventilation requirementSufficient to clear fumes and maintain oxygen above 19.5%
Practical Notes
Strict compliance with IS 4081 is mandatory when handling and firing explosives during tunnel excavation.
Continuous mechanical ventilation must be maintained to dilute noxious gases (like CO, NO2) and silica dust after every blasting cycle before workers re-enter.
Scaling of loose rock from the roof and sides must be performed meticulously after blasting and before mucking operations commence.