Medical support for the sydney airport link tunnel project.

Abstract

In 1996 a contract was awarded to construct a tunnel connecting Sydney Airport with the rail network. The project involved driving a tunnel through soft ground over a distance of 5.5 km. Medical input involved planning compression and decompression, assessment of fitness to dive, training of workers and lock operators, health monitoring of workers and treatment of related injuries. Oxygen decompression tables were used for the first time in Australia, the UK or US, although they have been successfully employed elsewhere. Oxygen tables improve efficiency and may reduce the risk of decompression illness (DCI). 22 individuals were declared unfit to work in compressed air. Over the course of the project there were 767 entries into raised pressures (interventions), with a median of 4 workers each time, at pressures ranging from 1.75 to 5.02 bar gauge (175 to 502 kPa absolute) with an average time at the cutter head of 3 hours 2 minutes. Compression related problems included 8 cases of decompression illness. The incidence of DCI was one case every 286 man interventions (0.35%) and this problem affected 5.9% of the workers. This incidence compares favourably with that of projects using air decompression. The combination of the Tunnel Boring Machine (TBM) and oxygen decompression, in a context of vigilant medical supervision, provided a safe working environment. We recommend this approach in the future.