Emirates Air Line, London, UK: south tower substructure in the River Thames

Abstract

This paper, the second in a series describing the delivery of the Emirates Air Line project in London, UK. It presents the challenges associated with the delivery of the south tower base to the 90 m steel tower, in the tidal Thames, to a tight programme, with an Olympic deadline. The paper presents an appraisal by the team of the given reference design of caisson construction at tender and the decision to develop a different design to meet programme. This is followed by a detailed optioneering of the design of the substructure elements leading to selection of the optimal approach employing large concrete precast elements for site assembly. The elements included a protective silt skirt to avoid erosion of the riverbed. Aesthetic considerations are discussed, including the tower, located offshore on piles that are visible at low tide, which required careful attention to the compositional aspect of its overall substructure. To continue the elegant form of the twisting tower, the piles were fitted with double curved precast concrete sleeves to continue the curvature of the steel ribbons down into the Thames. Finally, construction challenges are outlined and a description is given of the dramatic site delivery of the 200 t precast skirt using river-based shear legs.