THE ART OF SUCCESS UNDER HEATHROW

This article describes the 1.3 km long Airside Road Tunnel (ART) project at Heathrow Airport. The requirements in building the twin- bore 8.1 m diameter parallel tunnels involved minimal clay cover, minimal ground movement, and zero unplanned impact of the operation of the airport and the Heathrow Express running tunnel. A tunnel boring machine (TBM) was specifically designed to meet construction challenges, which also included retaining the excavated London Clay in working condition for future work. Moving Exclusion Zones were used as mitigation measures, designed to keep aircraft movement directly about the TBM to a minimum and thus reduce the potential for ground movement. Since the alignment of the ART involved a vertical crossing over the Heathrow Express tunnel, real time monitoring was installed in the tunnel in order to allows for the unrestricted operation of train services on the Heathrow Express. The article discusses the TBM operation and performance, as well as the challenges that were faced in managing overall construction.