The new Terminal 5 main building at Heathrow airport (bottom left) has a roof structure with a total weight 18,000t. On completion, this roof structure will be the largest single span building in the UK, with the floor space occupying the equivalent of 50 football pitches.
The single wave effect is formed by 22 steel box rafters forming perfect bow string arches, supported along each side by 11 pairs of steel support abutments. Fagioli PSC lifted this roof in six parts during a nine month construction period. The strand jacking was carried out by 16 computer-controlled L180 jacks, powered by individual electric power packs with all jacking operations being undertaken from a central control cabin located on the ground. Each section had to be lifted to an elevation of 39m while staying within the design tolerance of 50mm. Each of the six operations was performed within a single day.
The strand jacking option was chosen because the working height limitation of 43m (dictated by airport’s radar system) ruled out the use of cranes. The other benefits were the ability to carry out roof cladding and other activities at minimal height with safety, programme and quality benefits associated with working at ground level.
Meanwhile, the new visual control room (VCR) tower at Heathrow Airport, near Terminal 3, has started to take shape.
Fagioli transported the 27m high cone-shaped top section of the tower, weighing 900t, almost 2km across the airfield late last year using three six-axle self-propelled mobile transporters controlled remotely.
The top section was pre-fabricated on a site inside the airport’s southern boundary to minimise the impact on Heathrow’s operations. Throughout 2005, Fagioli PSC will lift the tower using three triangular 16m towers and three L600 strand jacks.
The tower’s top section will be lifted 12m at a time, ready to install five 4m by 12m steel sections underneath.
