MANAGING RISK AT T5

Terminal 5 at London's Heathrow Airport will add capacity for 30 million passengers when completed. It will require about 14 km of tunneling for road and underground rail links, and include stormwater outfall and expanded segmental lined twin bore tunnels. This article provides an overview of the risk management strategies developed by a multi-company integrated team for the tunneling works, the electrical and mechanical elements, the civil and tunnel design and the specialist site support. In the wake of recent major tunnel collapses such as the earlier Heathrow, Munich and Nicoll Highway, the team adopted a non-adversarial contract approach to get participants' fullest cooperation in joint risk management. This was embodied in the T5 Agreement. Ground movements were considered one of the major risks and they were monitored. Describes innovative solutions to problems posed by local geology, settlement hazards, face confinement pressures and constraints on route selection. Steps had to be taken to maintain a 2 bar confinement pressure. The project was successfully completed without incident and under budget.