T5A roof: the abutment first run study

The abutment structures provide the support for the main span of the dramatic 176 m free-spanning roof of Heathrow's Terminal 5 ( T5) main terminal building. The abutments contain many complex engineered components, which are replicated 22 times throughout the roof structure. The roof modules were essentially made up of the central portion of the span containing the majority of the roof cladding supported by a 107 m bow-string arch structure, which was in turn supported by the end abutments which form the subject of this paper. The programme for the construction of T5 was time-critical and relied heavily upon constructing the roof in a series of modules to an extremely ambitious cycle time. The construction of the abutments was key to achieving these rapid cycle times. In order to ensure that the cycle times could be achieved, BAA embarked upon what was termed the abutment first run study ( AFRS) essentially to determine, ahead of the construction on site and offline from the critical path, that these crucially important cycle times could be achieved. The current paper describes the rationale behind the study and the preparations made for the construction of the AFRS at Severfield Rowen's facility in North Yorkshire. The paper focuses on how practical refinement of complex installations can contribute to savings of both time and cost and how attention to detail during the design and manufacturing phases ensured that the components successfully fitted together. The effectiveness of the AFRS helped to guarantee that when the roof module was suspended from the strand jacks some 30 m in the air, the support points on the abutment structure were correctly aligned.