Slabs were cast to form the future roof of the underground station. This station was one of the first to be designed under new legislation following the Kings Cross Underground fire, sufficient headroom was required for smoke extraction to enable a train to burn safely at the platform.

Enabling Works for a future underground metro station beneath the new bus station involved creating retaining walls using contiguous augered piles. Isolated piles were installed to become future columns along the platforms.

Beams up to 3m deep were cast to span between columns and across the future tracks.

Lines of contiguous augered piles were connected at the top with deep concrete beams. These formed the load bearing retaining walls of the metro station and track. The roof slab was cast across the top between the two lines of piles.

The detailed design for the Enabling Works was carried out under a design-and-build contract that enabled us to concentrate on the detailed design of the bus station structures above (see sheet 2 of 3). Construction of the bus station commenced as soon as the enabling works were complete.