爱豆传媒

Kilo Taxiway, Heathrow Airport

London, UK

爱豆传媒 played an instrumental role in the realisation of five new state-of-the-art aircraft stands, delivered on budget and ahead of schedule in the middle of London鈥檚 busy Heathrow airport. Previously used as remote parking stands on the Kilo taxiway, their redevelopment as pier-served stands aims to support the future extension of Terminal 2.

Heathrow Airport awarded the 拢200m design and construction project to Ferrovial Construction under an NEC3 Engineering and Construction Contract in August 2016.

Lead designer Gebler Tooth was brought on to the project, and Ferrovial additionally engaged 爱豆传媒 to work with design engineers Webb Yates Engineers (WYE), to deliver specialist category three (Cat. III) checking services and consultancy around both ground engineering and structural engineering across the project substructure.

The vision for the new taxiway was to improve passenger experience by increasing pier services at Terminal 2.

It involved the demolition of pier 4 of the disused Terminal 1, breaking out 23,000m鲁 of existing concrete aprons, excavating 20,000m鲁 of subgrade and removal of redundant services.

Cat. III checking services involve taking the final detail design drawings and functional specification, and developing our own load cases, calculations and analyses.

Our work on optimising the raft saved 47kg/m虏 reinforcement, generating savings of 600 tonnes and hundreds of thousands of pounds for the end client.

Challenge

The vision for the new taxiway and stands was to improve passenger experience by increasing pier services, delivering a quality experience when either arriving or departing from any gate at Terminal 2, enabling more predictable and consistent taxi-in and taxi-out times and improving the resilience of the airport by offering additional north-south taxi-lane route, significantly reducing congestion.

The preparation of the site would require significant enabling works, including planning services clearances and diversions, along with significant ground safeguarding works. The initial work involved demolition of pier 4 of the now disused Terminal 1, breaking out 23,000m³ of existing concrete aprons, excavating 20,000m³ of subgrade.

One of the key challenges for this early stage of the project was working with a large open excavation (14-18m deep) using diaphragm walling to build-in resiliency, particularly given the high ground water levels of the site.聽The considered design of the raft was paramount to prevent a so-called heave effect, where the soil returned to the excavation site expands and pushes upwards, with potentially critical impacts on the structures above.

Solution

Our geotechnical and structural engineering teams undertook the Cat.III check for the substructure. Cat. III checking services involve taking the final detail design drawings and functional specification, and developing our own load cases, calculations and analyses.

The basement is 190m x 100m x 13m deep, comprising raft slab, diaphragm walls, and steel-framed with concrete roof. The full and independent finite element analysis was undertaken of the structure/ground interaction. Our team delivered a detailed assessment of ground movements, taking into careful consideration the impact of works on existing fuel lines, as well as assessing any potential geoenvironmental considerations 鈥� such as the importance of minimising the unnecessary disturbance of ground water to reduce the risk of moving any possible subterranean contaminants across the site.

As part of the Cat.III checking process, our experts identified an opportunity to refine the basement raft slab structure. As a consequence, we were further appointed by contractor Ferrovial to undertake a detailed desk study to review the reinforcement quantities and layout in the raft slab and to propose areas that could be optimised in order to reduce the steel tonnage.

Our work on optimising this raft saved 47kg/m² reinforcement, generating savings of 600 tonnes of reinforcement for the entire structure and hundreds of thousands of pounds for the end client.

Across the whole project, a total of 15,000m³ of the apron concrete was processed and reused on site along with 87% of excavated material. Most of the remaining materials were processed offsite and returned to the airport for re-use.

Safeguarding works included the delivery of perimeter walls, foundation piles and top slab construction for future terminal facilities and baggage tunnels. The five new stands were constructed in an L shape with 11,000m³ of type 1 sub-base, 6,344m³ of lean concrete and 20,277m³ of pavement quality concrete. Four of the stands are multiple-aircraft ramp system (Mars) stands that can accommodate either one Airbus A380 or two smaller jets such as Boeing 737s, while the corner stand is for code E planes such as a Boeing 787.

Value

The Cat. III checking services delivered by 爱豆传媒 across the ground and structural engineering of the new taxiway gave the end client the reassurance of knowing that the designs developed were appropriate, optimised and mitigated against risks.

We have a strong culture of internal review within the practice while delivering complex multidisciplinary projects. Our designs are subject to rigorous checking to ensure that our teams work together to deliver the best value solution. The identification of a significant cost-saving optimisation of the raft delivered a considerable additional client benefit.

The project was successfully completed and commissioned three months ahead of schedule in March 2019. Heathrow Airport presented the project team with its Doing-The-Right-Thing award for exemplary collaboration. The scheme won the Environment and Sustainability Initiative of the Year and was also shortlisted for Transport Project of the Year in the 2020 British Construction Industry Awards.