In Zürich, a crack Anglo-Swiss project team including Grimshaw and Arup have used imagination and pragmatism to bring glamour back to air travel. Martin Spring takes a tour around the airport that is a bit of a departure.
Flying from London to ZÜrich provides a succinct tale of two airports. Setting off from Heathrow Terminal 4, British Airways passengers leave a cavernous, nearly windowless, crinkly-tin box where they have to struggle through the myriad shops, cafes, airport facilities and security officials all going about their serious business. Arriving at Zürich airport an hour-and-a-half later, they waft along wide, airy concourses on polished granite floors while the shops stand discreetly aside, cafe-bars radiate suave glamour and an immense window wall gives a grandstand view of the runway and the hills beyond.
One moral of the tale is that airport terminals are such highly complex, commercially driven, intensively technical buildings that, left to their own devices, they would put all but hardened masochists off air travel for good. Another moral is that, given a bit of imagination and goodwill, airports can also bring exhilaration back to air travel.
It follows that Zürich airport was designed by a top architect and engineer and developed by an enlightened airport authority. British architect Grimshaw and engineer Arup won an international design competition in 1996 in a joint venture with a Swiss architect and engineer, Itten & Brechbühl and Ernst Basler & Partner. In the competition brief, the airport authority made it clear that it wanted the airport to be extended so as to double capacity from 15 to 34 million passengers a year, making it one of Europe’s top 10 air-transport hubs. It also held up the classy Oslo and Copenhagen airports as models rather than commercially compromised Heathrow.
According to Grimshaw director Chris Nash, the Anglo-Swiss team won the competition with a design that was “by far the most pragmatic” – not a characteristic usually associated with this flamboyant architect – “and by far the most exciting and emblematic.”
Of the two buildings designed by Grimshaw, the more exciting and emblematic is the newly completed airside centre. This is the building that is dominated by the immense window wall overlooking the runway. The window wall is a heroic inward-sloping expanse of nearly clear glass, a full 250 m long and 25 m high. Overhead, a lightweight roof curves down gracefully on either side and at the rear. Directly behind the window wall, slender, sloping columns in white tubular steel soar upwards in interlinked A and V-shapes to support the roof. In true Grimshaw style, the columns combine sculptural elegance with structural honesty, as they taper towards large, clearly articulated pin joints at floor and ceiling.
Just inside the window wall, a seating area stretches along the whole length of the building. This is a true chill-out zone, where passengers can bask in comfort, quietly absorb the view and soothe any nerves frayed by travel. They are assisted in this activity by two bijou pocket cafe-bars and a restaurant that are spaced along the open concourse. Cafe tables and mustard-yellow chairs placed in intimate curlicue arrangements are punctuated by bamboo copses.
This cool, calm departure lounge is bounded on the inside by a long double-storey screen, the top half of which is faced in natural wood veneer. The screen shields the seating from the noise and bustle of that mainstay of the airport departures hall – the duty-free shops.
The duty-free shops are arranged on two storeys on either side of malls that curve gently round in a crescent shape. All the usual gaudy suspects are present – chains plying liquor, cigarettes, cameras, perfume and jewellery – yet they confine themselves to the continuous sweep of shop fronts allotted to them without crowding or jostling passengers heading for their departure gates. What’s more, the two curving shopping malls are broken at either end and in the centre, inviting passengers to take in the expanse of space and light, admire the view, slump into a comfy seat and gulp down a drink before rushing on again.
The double-height departure hall had to be built out over the existing inside service road, which could not be moved. This meant the arrivals hall, where passengers queue up for passport control, had to be pushed underground (see diagram left). In contrast to the airy, sweeping, crescent-shaped departure hall above, this is a rectilinear hall in the Swiss rationalist tradition. Three regular rows of cylindrical concrete columns march through the space, beneath a flat cherrywood-veneered ceiling with skylights. In the lower basement, a station to an underground shuttle train leads to a remote passenger terminal.
The airside centre has all the regular geometry, airiness and glamour of a top-notch standalone passenger terminal. Yet it is not a standalone building. It is not even a self-contained passenger terminal. And this is where the pragmatism of the Anglo-Swiss team’s design comes in.
Before their intervention, Zürich airport comprised two passenger terminals built in 1954 and 1972. Whereas their rivals in the architecture competition would have swept these away to create a giant, all-encompassing terminal, the Anglo-Swiss team took the more expedient route of inserting two new buildings linked to existing ones, much as Grimshaw was doing at the time at Manchester airport. In Nash’s phrase, the additions have been “knitted into” the existing airport complex.
As conceived by Grimshaw and their colleagues, the airside centre bridges the gap between the existing terminals. It serves as an efficient and attractive transit zone, moving arriving and departing passengers between the aircraft docking piers and the check-in desks and baggage reclaim halls in the terminals. In this sense it is a hub that unifies the airport complex.
The other building designed by the same team and completed in March 2003 is likewise a transit zone and hub. Known as the landside centre, it is effectively a transport interchange for passengers arriving by train, bus and car. Just like the airside centre, it knits into the existing buildings on either side – in this case a wide shopping mall leading to the passenger terminals.
In terms of circulation, security and servicing, there are few buildings more complex than airport terminals, and knitting together new and existing buildings only increases the complexity. At Zürich the interfaces between the new and the old total 1.5 km in length, if each storey is calculated separately, according to Grimshaw senior associate Kai Flender. To complicate matters even further, the floor levels do not match up among the existing buildings, as the site slopes across them.
The slogwork of connecting the internal spaces, fabric, structure and services of the new buildings to the existing ones was largely carried out by the Swiss partners in the joint venture. The big achievement is that passengers are largely unaware that they are passing through several buildings of different ages, layouts and finishes.
This nearly flawless continuity in the public concourses is achieved by several means. Continuous floor surfaces in polished stone or composite give a sense of unity, even though the type of granite, marble or terrazzo differs in each building. The two infill buildings must also take up the difference in floor levels – as much as 900 mm in the airside centre – and this is done by means of barely perceptible slopes in the floor rather than by the impediment of steps.
Most of all, this seamless effect is created by the design team’s adherence to five design principles that, despite their British contribution, have an undeniable Swiss rationality to them.
As Flender relates, the five principles are calmness, clarity, contrast, transparency and freshness.
The airside centre, for instance, offers calmness in the secluded seating area, clarity in the sweeping malls on the two upper floors uncluttered by projecting shop fronts, contrast between the airy double-height departure lounge and the rectilinear immigration hall below, transparency with the grand view through the window wall, and freshness with the natural timber enclosures to the shops.
Elsewhere, passengers must negotiate a few abrupt changes in direction, or rise or descend by escalator to different storeys. Here again, visual clarity comes to their assistance. Destinations are indicated by a system of illuminated signs – designed by Grimshaw – that are uniform, bright and clearly legible. In the landside centre, where passengers departing by train must descend three storeys to the railway platforms, their route is clearly indicated by freestanding escalators passing through a spacious central void topped by a large circular rooflight. This effortless transport interchange within a single building brings to mind Amsterdam’s vast but efficient Schiphol airport.
The two buildings added by the Anglo-Swiss team provide a total of 128,000 m2 of new and remodelled space at a combined cost of £291m. Although they are only part of an even more extensive airport expansion costing £965m in total, they show how an airport can be unified and doubled in capacity by the pragmatic, sustainable solution of knitting in additions. They also show that such a pragmatic approach can at the same time bring back the exhilaration and glamour that has been squeezed out of air travel. And they help explain why BAA selected Grimshaw, in preference to Foster and Partners, for the job of expanding London’s Stansted airport.
Grimshaw, Itten & Brechbühl
Structural and services engineers
Arup, Ernst Basler & Partner
Project and construction manager
Itten & Brechbühl
NO TAKING ON EXTRA FUEL …
Although Zürich Airport was designed to expand by some 50% in floor area, planning permission stipulated that there should be no increase in energy consumption over a 10-year cycle up to 2005. Nor could the airport’s large district heating installation be increased in capacity, even though it was extended in coverage. Several measures were adopted to reduce energy consumption.
The west-facing window wall in the airside centre has clear glazing to maximise views and solar gain. On sunny afternoons horizontal, perforated aluminium louvres automatically swivel downwards to cut off excess sunlight while allowing views through. Overall, the building envelopes were designed for low heat loss.
The lofty departures hall would have suited a low-pressure air-displacement system. But since its floor levels had to match those of adjacent buildings, this left insufficient space in the floor zones to fit in air-supply ducts. Instead, a modified air-displacement system was used in which air is supplied at ceiling level. Elsewhere, ducted air-distribution systems were replaced with low-pressure systems. All this reduced the frequency of air changes and energy consumed.
The downside of the reduced air changes is that internal temperatures fluctuate widely. Temperatures in the airside centre can fluctuate between 20°C and 28°C, whereas the normal benchmark for such a building would be 22°C.
HOW THE AIRSIDE CENTRE ABSORBS THERMAL AND STRUCTURAL VARIATIONS
Measuring 250 m by 46 m, the steel-framed roof of the airside centre is designed as a single monolithic structure. With no internal expansion joints, it expands and contracts in heat and cold by as much as 35 mm on all sides. This expansion is taken up on the side of the window wall by steel A-frames that can pivot slightly on their pin joints, and on the opposite side by a sliding Teflon layer sandwiched within the head of each vertical steel column.
The west-facing window wall is hung from the roof and expands and contracts in heat and cold at its base. Movement joints at the base allow the mullions to slide up and down within the floor zone of the departure hall.
The clearly articulated pin joints at the base and head of the A-frames in the airside centre were at first intended to be cast in steel. But since the floor slopes by 900 mm across the hall, all the joints vary slightly in angle, making a standard casting mould inappropriate. Instead, Swiss roof contractor Tuchschmid Engineering recommended that the joints be fabricated out of steel plate, laser-cut to pattern and welded together. They came out as seamlessly precision-engineered as top-quality castings.
A TURBULENT JOURNEY – BUT ARRIVED ON SCHEDULE AND AT A LOW COST
Costing some £965m, the fifth expansion to Zürich International Airport is the largest building project ever undertaken in Switzerland. The two terminals designed by the Anglo-Swiss team cost £291m.
Eight years on from the design competition, the terminals have been delivered with impressive quality, on schedule and a full £19m below budget. Although this can be taken as a tribute to Swiss efficiency, not to mention the contributions of Grimshaw and Arup, the project suffered several major jolts, each of which could have grounded it for good. Out of the full development team, only the designers have remained on the project from start to finish.
The first jolt was that the national airport authority was privatised. “It was all change with new staff, and it went hugely commercial,” recalls Grimshaw director Chris Nash. One result was that retail areas in the airside centre doubled in size.
The second came when Switzerland considered joining the Schengen agreement, which allows free movement within European states. This would have turned Zürich into a two-stream airport, with domestic arrangements for European passengers and full passport controls for international flights.
This meant an extra floor had to be added to the airside centre and its roof re-profiled. In the event, Switzerland did not sign the Schengen agreement, and this extra floor has largely been devoted to retail.
The third jolt was the combined effect of the 9/11 attacks, which curtailed international tourism, and the ensuing bankruptcy of the airport’s anchor tenant, Swissair.
Fortunately this occurred too late to halt the development process or even to change the brief, although the effects are still felt in lower-than-predicted throughput of passengers.
Designing and building the two new buildings and adapting the existing complex went relatively smoothly under the control of an 80-strong site design team.
This process included 18 months of partly demolishing and adapting the existing terminals while they were fully operating. Grimshaw senior associate Kai Flender sums up the process: “It was like open-heart surgery, cutting into the living arteries of the airport.”