London’s second largest international airport is replacing one of the original piers on its South Terminal to improve efficiency and passenger experience.
The last few scraps of cut steel and fragmented concrete were being hauled away from Gatwick Airport by contractor Vinci in mid-October as the four-month demolition of Pier One finished. Concrete foundation pads were being cast for a brand new terminal extension to replace it and recycled concrete was being placed for new aircraft aprons.
Once a symbol of London’s growing air transport capacity in the 1960s, the pier had become tired and difficult to maintain. Internally it was relatively dingy and poorly lit, ceilings were low and the space cluttered.
“It has been somewhat showing its age,” says Gatwick head of piers infrastructure and airfield projects Ben Green, who is in charge of the £184M replacement scheme.
“It certainly does not suit Gatwick’s ambition to be seen as London’s passenger friendly airport of choice.”
The pier is much the smaller of two on the airport’s South Terminal, familiar to many holiday and business travellers. Pier One was originally designed in the days of turbo-prop aircraft and, despite upgrades and modernisations, it somewhat clutters up the terminal operations for both passengers and aircraft operations.
“The stand layout outside is inefficient, especially for modern aircraft types,” explains Green. A kind of cul de sac between the small pier and its larger Pier Two neighbour means that aircraft have to be reversed out and turned to reach the taxiways, and they often back into space needed by other aircraft.
All this will be solved by the new terminal extension building, which is to occupy a very different footprint - a compact rectangular area close to the airport perimeter. Around it will fit five plane stands, replacing the eight there at present. All are linked directly by air bridges to the gate rooms.
“But because of the chance to repave and enlarge the parking area and reconfigure its movements, these fewer stands will allow more passenger throughput,” explains Green. The stands will also handle larger aircraft than before.
The unusual shape of the new pier is not just to do with a tighter footprint in a space close to the busy Gatwick main runway. It also accommodates another feature of the project: a total renewal of the baggage handling system.
Based on modern automated warehousing technology using “totes” or standardised plastic trays, this will be a new ergonomically efficient system, reducing baggage handling effort and improving efficiency. The conveyors and handling lines will be at the heart of the new building.
The new system increases capacity from 3,800 to 4,250 bags an hour, but on top of that it will include an “early bag store”, which can hold 2,600 bags.
“The handling system is crucial and in a sense the terminal is built around it,” says Gatwick construction director Derek Hendy.
Originally, the £45M baggage system and the new building were separate projects but it made good sense to merge them into the now £184M project.
You are trying to fit a vast Meccano structure into a complex 3D space and there are thousands of points where you can get conflicts
Jason Griffiths, Vinci
Doing so has partly dictated the rectangular floor shape but this also comes from the need to fit the new pier into a space close to the runway. The position also determines an essentially two-storey format squeezed in underneath the radar profile for air traffic control.
For Vinci this limited envelope and a requirement limit interference with existing underground services have been key constraints for the project. The contractor’s remit includes detailed design work as well as the physical demolition and reconstruction, and much of the first year has been occupied with the design, overlapping onto the start of site work in June.
“Gatwick provided an outline design for the tender and we put together a proposal as part of the tender,” says Vinci south east regional director for air Jason Griffiths.
The contractor worked with Arup for airfield works, Brydon Wood for structures and Beumer for the baggage handling system. The team offered various improvements.
“For example, we were able to consolidate some of the small plant rooms and put them towards the back of the building,” Griffiths says.
That allowed the gate rooms to have larger picture windows and helped keep the internal layout tight, reducing the walking distance to the gates.
Vinci also worked hard on the building structure to squeeze as much as possible under the radar line. A relatively thin pre-stressed floor slab helped reduce the structure’s height as did a maintenance free slim-line roof.
“But the major work in the design, maybe 75%, is around the baggage handling,” says Griffiths “both in finding the appropriate supplier and technology and then in making it all fit.”
Building information modelling (BIM) was used to build up a huge 3D data model of the entire airport, and it came into its own, says Griffiths. The tender process was already facilitated by BIM procedures, and then working straight into a 3D model allowed the complex work of integrating the handling system and the building to go exceptionally well.
“You are trying to fit a vast Meccano structure into a complex 3D space and there are thousands of points where you can get conflicts or need to leave space for maintenance, access and egress. All that with tolerances in the tens of millimetres,” says Griffiths.
By exporting the 3D model into baggage simulation software, it has been possible to run hundreds of “what-ifs” to satisfy everyone that the system will work from day one.
Virtual modelling has also helped streamline the wayfinding and signage for the new interiors, and for familiarising and training ground staff. “It is the only way to do a project as complex as this,” says Griffiths.
Work for the new pier began in June with the start of demolition. Since then most of the old steel frame and concrete pier have been crunched up with hydraulic shears, and a giant mobile guillotine - an American 8600 Badger Breaker with a 12t hammer over 2m wide.
“We are getting fairly high rates of recycling, particularly for the 40,000t of old apron and taxiway paving which is taken to a local yard in Reigate for crushing. It makes excellent subbase and foundation,” says Griffiths.
Another clever move was the decision early on to keep the project land side. Airport security fences were temporarily moved to bring 90% of the pier outside the perimeter thus ruling out the need for high level security checks for construction workers.
Building work is now in train with the pier due to open next June and the baggage “factory” in August. Final completion is due in December 2014.