Heathrow Terminal 5: tunnelled underground infrastructure

Terminal 5 at London's Heathrow airport was one of the largest infrastructure projects in Europe over the last five years. It included approximately 14 km of tunnelling to provide underground infrastructure for rail, road and effluent discharge. In all cases the tunnels were delivered without major incident, thanks to a single integrated team which made all aspects of risk management central to its delivery philosophy. This paper describes the four key projects for which the key aspect of delivery was tunnelling – the airside road, the storm water outfall and the Piccadilly line and Heathrow Express extensions. It discusses the range of aspects that made up the delivery of this infrastructure, ranging from design through to performance of tunnelling machines and the control of surface settlement.