The large-scale Kilo Apron Development at Heathrow Airport is now nearing completion.
Webb Yates Engineers have been working closely with Gebler Tooth Architects for Ferrovial Construction to provide structural and civil engineering design services for the large-scale Kilo Apron Development (KAD) at Heathrow Airport.
The project involves the demolition of the 1960’s Euro buildings between Terminal 1 and Terminal T2B on the central Heathrow Airport site. It enables the future completion of the T2A building as well as the new taxilane to be constructed. To minimise future disruption of the site an Early Bag Store (EBS), Hold Baggage Screening (HBS) and Tracked Transit System (TTS) were constructed below the taxilane. In addition to the demolitions, a large amount of services beneath the taxilane had to be diverted as part of the scheme’s enabling works.
The substructure consists of a very large basement, measuring approximately 200m long by 100m wide with a base around 18m below ground. The perimeter of the basement is lined with 1.2m thick reinforced concrete diaphragm walls which allowed for top-down construction. The roof is formed by a reinforced concrete slab spanning between large fabricated composite beams. Steel columns support the roof and transfer loads on to a 1.5m thick raft slab which acts as the foundation.
To ensure ground movements from excavation or construction did not cause damage to nearby adjacent structures such as the Terminal T2B basement or T2 Passenger tunnel complex geotechnical analysis was carried out to determine likely heave and settlement movements. These movements were then checked against the tight tolerances required by the baggage equipment and operational requirements of the taxilane above.
As well as ensuring the structure connected into the existing T2B basement, it was also designed to safeguard for future extension of the basement towards Terminal 2. The diaphragm walls were extended past the Western edge for easy connection and the Western edge of the slab was designed to cantilever, without relying on support from the walls, to reduce the amount of temporary works needed in future works.
The design utilised several novel techniques to reduce the amount of construction time and improve sustainability such as prefabricated reinforcement cages for the diaphragm walls and roof slab, and the use of HVO hydro-treated vegetable oil as renewable fuel for excavators.
* Photos were taken pre-Covid.