Swansea Sail Bridge

The 140m North Bridge, named the "Sail Bridge" by the Welsh Assembly Government, is an iconic design explicitly required by the Client and City Council to form an emblem for the regeneration of the Port of Swansea.  Though the structure of the North Bridge adopts a classic symmetric cable-stayed configuration, in cross section the deck is held along only one edge.  The simplicity of the overall form is augmented by the apparent delicacy of the asymmetrically suspended walkway.

The 42m high mast, of varying cross section, is fabricated from a series of flat and rolled steel plates of decreasing thicknesses from base to tip.  The cross section migrates from a filleted square at the base through to a kite shape at mid height, culminating in a triangular configuration at the tip.  This developing form is achieved without the use of warped planes [all faces are ‘flat’] and yet the final form is visually complex.  The plate thicknesses in the mast vary from a maximum of 45mm at the base to 10mm at the tip.  The final craneage weight of the mast was 78 tonnes from an initial material procurement tonnage of 93 tonnes, and the mast was lifted in one piece using a 1200 ton crane on the west bank.