This paper describes the design and construction of the two terminal buildings in phase 1 of the £4·3 billion Terminal 5 development at London's Heathrow airport. A total of 40 000 t of steel was used to create 280 000 m2 of space in the dramatic main terminal building, T5A, including forming a clear span roof of 156 m by 396 m to enclose it. In addition to high visibility for passengers, the design provides maximum flexibility for future modifications. In the first of two satellite buildings, T5B, 600 000 m2 of posttensioned flat slabs were cast using minimal amounts of formwork and site labour. Building these vast structures at the world's busiest international airport also meant all construction operations had to be undertaken within a highly restricted space and with no cranes allowed above roof level.

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.

The 176 m free-spanning dramatic roof structure of Heathrow's Terminal 5 main terminal building will undoubtedly become one of London's iconic buildings. This paper describes the various processes that the roof team used to ensure compliance and system integrity in order to guarantee that the 17 000 t structure could be built safely while negotiating one of the project's critical paths. The paper describes the engineering issues and how collaborative working contributed to achieving one of BAA's most successful sub-projects. The focus of the paper concentrates on the structure and describes how the design criteria set the fundamental requirements for the construction operations while the design of both permanent and temporary works was developed together. It details the rigorous review and approval processes and describes why risk assessment and compliance audit were crucial. The importance of the team structure and how this operated in conjunction with the lifting protocol to guarantee the success of critical operations is emphasised. It covers the development of the engineering procedure and how this was used to develop the hold points to control key stages. A full description of the construction engineering studies is provided to highlight the complexity and extent of preparation undertaken.