ABSTRACT
The Heathrow Express (HEX) Rail Link provides a fast direct connection between the airport and central London. A principal component was the new underground station in the airport’s Central Terminal Area (CTA). The multi-storey car (MSCPs) in the CTA appeared to be as typical construction of their kind and all of them, including MSCP 1A, had performed as expected. The original tunnel construction for the CTA station was undertaken using sprayed concrete linings as the primary support. The narrower sub-surface trough is shown with a greater magnitude of settlement at the upline tunnel axis. The orientation of the diagonal cracks was consistent throughout occurring in the column faces at right angles to the alignment of the tunnels. Pilot tunnels with a diameter of 3.3 m were also driven ahead of the main shields to further aid control of settlement.
