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by the NFCC

Work in compressed air (Pressurised atmospheres)

During the construction and refurbishment of tunnels and subsurface infrastructures, compressed air can be used to manage ground water and to stabilise the face of the excavation. The nature of compressed air working has changed significantly over the years to reflect developments in tunnelling technology and techniques. Long periods of work in compressed air chambers using hand excavation techniques have ceased to be the norm, as the majority of underground structures are constructed using tunnel boring machines (TBM) or other methods. This has resulted in much lower levels of exposure to pressurised working environments.

Exposure to compressed air is now generally limited to periodic but short excursions into the cutting head of a tunnel boring machine (TBM) for inspection and maintenance. Given the relative rarity of compressed air tunnelling work, the emergency services will have little or no experience of dealing with hyperbaric emergencies. Such operations are specialist in nature and are not activities that normally involve fire and rescue services, other than to provide support and assistance to specialist teams.

The contractor in charge of the pressurised working operations should assist the fire and rescue service in planning its response to an on-site emergency. That assistance will extend to providing equipment and training facilities. Emergency exercises should be undertaken early in the works period and at intervals of not more than 12 months thereafter. The contractor in charge should work with the emergency services to allow them to undertake simulations and joint exercises to improve their ability to respond to emergencies.