T5 is such a huge project that defining its content, shape and ethos, let alone designing the solution, is a major task, reports Adrian Greeman.
BAA has an 'expert client' team in place for T5, to juggle with a multitude of competing users' desires and needs. It is headed up by architect Mike Forster.
'We are the 'what' and the 'why' of T5, rather than the 'how' or the 'when', ' says Forster who has been managing the 55-strong team for the last 18 months as the project has really begun to move.
'We set the brief for what is to be included in the whole package, working in a completely integrated way with the whole design and construction team.
'Perhaps I should say, the 'what' of 16 packages - because a scheme of this magnitude is just too big to think about as a single entity. We are working on giant projects that cover transport interchanges and tunnels, airside civil engineering for taxiways and standings, and landside motorway links and landscaping on a large scale, through to baggage handling and the buildings themselves, the main terminal and the satellites.'
It is also too long term a project to fix in a single pass, or a single set of documents. Forster's team will continue working on the scheme almost until the beginning of its six-month operational testing period in 2008. Integration and interaction will be continuous.
There are two main reasons for this. First, condensing the wishes of around 43 different stakeholders into a brief and the subsequent design is an iterative process, he says, with advances in the design producing impacts on elements throughout. These further modify needs, if only to make sure cleaning can be done easily, or engineering has easy maintenance access.
Constant balancing and judicious compromise is needed to accommodate everyone from major occupier British Airways, various security agencies and Heathrow Airport itself, through to retail store operators. And to keep on budget, of course.
But secondly, there is a crucial need for flexibility. The project will last for nearly a decade in an industry that is not only constantly changing but which has recently been coping with the dramatic impact of 9/11 events, the rise of the low-cost airline and the IT revolution.
'We cannot constantly revise the design but we are working on a basis of 'progressive fixity', ' explains Forster.
'At present, the shell and core are defined but the work on the interiors remains open.'
Even then, as the brief coalesces, he says, the aim will be to keep the structure as flexible as possible.
There is an overall strategic view. And that is summed up as 'Heathrow-ness'. T5 is very much 'Heathrow's new terminal' rather than 'a new terminal at Heathrow', says Forster.
Challenged to define the quality of Heathrow off-the-cuff Forster pins it down as 'a world airport serving the world's greatest city'. It is definitely not a low-cost airport and is different to Gatwick or others in the UK.
'It is seen as stylish, vibrant, pace-setting and internationallyminded, as well as responsible and alert, ' he says.
Naturally, BAA has looked across the world to inform the brief but, Forster emphasises: 'Don't forget that BAA operates a number of major airports in the UK and draws a lot on its own experience.'
One impact of this has been the search for what BAA calls 'wow factors' - aspects of the design that cause users to draw breath.
The rail station at basement level should be one of these and the landscaped setting for the building.
So too will the transport interchange space between the car park and the main building.
'There must always be a gap of at least 30m between car park and terminal for security reasons, ' he says. 'But usually this contains a Departures forecourt deck, which means arriving passengers see only the underside of a road deck where taxis drop people off at Departures.
'But because we have particularly high multi-storey terminal buildings, there is room for the Departures set-down point to be on the top level of the car park, leaving the space free between the buildings, with just slender footbridges providing across to the terminal (top left).'
Once wowed by that dramatic vertical space, passengers will see the enormous single span wave-form roof which covers the entire terminal building, creating a feeling similar to the great Victorian railway stations, he says.
And beyond that, after security checks, users will reach a cascade of three floors stepped downwards in front of a multistorey curtain of glass, with spectacular views across the 'the world's busiest airfield'.
The Richard Rogers architectural team, with an 'appropriate stature' for a project of this size, has been highly successful in 'articulating the concepts' in the brief, says Forster.
A second strategic imperative has been sustainability. As a key UK client and in a high profile industry, he says it is vital to be at the front on environmental and energy questions and 'at least' at best practice level.
Early on, the team set up an environmental advisory group, which consulted with bodies such as CIRIA and the Forum for the Future to establish targets. There is a particular emphasis on water use - a dual, recycled and potable system has been designed which will be fed partly by rainwater runoff and local well holes - and on hitting or exceeding CO 2emission limits, by a variety of light and energy use control mechanisms.
Noise levels and pollution reduction are also important and so too is the notion that sustainability should run right through the project. Not only the terminal design but its construction, fit-out and later operation should reflect sustainability concerns, says.
Sustainability is also part of the transport mix with the Heathrow Express and Piccadilly Line tunnel extensions to platforms at the lowest level helping achieve a desired 50% plus target for public transport use. There will also be two mainline platform spaces perhaps for future Crossrail or high-speed rail options.
Impressing the passengers will also be as much about the smooth operation of the terminal, its maintainability and cleanability, the sense that everything is operating properly. For this, Forster uses the word 'delightful' for the passenger experience.
But the devil, as the overworked phrase has it, is in the detail, and details are very much the preoccupation at present. To have maintainability, for example, means constantly working with the operations and engineering teams to get their input. Security and immigration also have their needs and demands.
And for the first time, the IT structure and systems of the building will be part of the process with its user requirement specifications (URS) feeding into the brief and the design from the beginning. That is no easy matter when the future technology of IT might well have shifted, and keeping cable channel layouts and other services easily reconfigurable absorbs a lot of time.
Forster says that his team and its subdivisions sit alongside their equivalents in the architectural and implementation teams 'and you would be hard pressed to distinguish which is which'.
Particularly important, he says, are the development managers for each of the five major project divisions - rail, baggage handling, buildings, civils and systems - who interact with the project leaders for the implementation of the scheme. 'That is the critical relationship, the fulcrum around which everything else pivots, ' says Forster.
Working on a giant project such as T5 demands flexibility from people, says Forster. It puts demands on them. But it will also be a giant achievement to create something that serves so many different needs.