ICE London Civil Engineering Awards 2013
Emirates Air Line
Principal Contractor: Mace
Client: Transport for London
Architects for concept, design and planning phase: Wilkinson Eyre
Structural Engineers for Mace: Buro Happold
Architects for Mace: Aedas
The Emirates Air Line is the first urban cable car system of its kind in the UK. Officially opened in June 2012, the cable car provides a 1.1 kilometre link across the River Thames, connecting the Greenwich Peninsula to the Royal Docks with a travel time of five minutes. The Emirates Air Line is part of the TfL Oyster Card network and provides a new sustainable transport mode carrying up to 2,500 people, the capacity of 30 buses, across the river in each direction every hour. 34 cabins operate continuously, each accommodating up to 10 seated passengers, with the ability to carry wheelchairs and bicycles.
The project provides an iconic landmark on the London skyline, connecting local communities, and improving access to destinations on either side of the river. The scheme has also proved to be a catalyst for a number of regeneration projects at The Royal Docks and Greenwich Peninsula, each a dedicated enterprise zone, including the new Siemens Technology centre completed in 2012.
The Emirates Air Line was completed by Mace in just over 12 months with the main tower structures completed in March 2012, followed by fitting out of the terminal buildings and cable car system in the spring, with testing, commissioning, trial running prior completed in June 2012.
TfL and its design team lead by Architects Wilkinson Eyre with Expedition Engineering and Mott MacDonald has worked closely with the Local Planning Authorities to design visually striking structures, including three ribbon-like tower structures, one rising out of the Thames. Mace’s Architects Aedas ensured that the final form and finishes of the stations and towers accurately reflected the planning requirements but were buildable within the challenging programme.
The strength of the design was crucial to the construction of the three main towers, two of which are over 85 metres high and weigh 570 tonnes. Designed using a complex helix structure providing stability to the structure the construction tolerances between the steel and concrete had to be very precise to maintain the continuity of the helix. The towers are made up of approximately 6,500 pieces of steel of varying thicknesses from 30 – 50 millimetre ribbons shaped then welded together before being connected to helix tubes that run inside the tower and provide the required stiffness.
To expedite the challenging programme, the Mace design team developed a detailed and precise geometric model of the complex double-curved tower structural steelwork. The Model has been used by all disciplines to coordinate the tower design, including Dutch fabricators who have employed advanced rolling technology to curve the steel plates to a high degree of accuracy. This innovative technology achieved a smooth outer skin, significantly reducing the amount of welded joints compared with conventional construction techniques.
The use of 3D modelling also helped to overcome the challenges faced, this was done with the help of Watson Steel, the largest specialist steel contractor in the UK. All of the towers were manufactured as assembled sections in Bolton in Lancashire and were erected in sections via cranes. The design team took the design for each of the towers and used cutting edge 3D modelling to create the precise measurements for each piece. This intricate modelling technique saw designs for each part drawn to within a millimetre to ensure every piece fitted together like a jigsaw. This process was very innovative for the UK; Watson Steel is the only factory using this technology taken from advancements on its other previous London based projects which include the Emirates Football Stadium and the Arcelor Mittal tower.
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