Santiago Calatrava: The things I create as a painter or sculptor are an important part of my work. Here in the office, I have a workshop where we make not just architectural models, but sculpture, too. Occasionally, I also design a piece of furniture. In the New York studio, I paint. My work as a painter and sculptor is very personal, but it nevertheless finds expression in my architecture as well.
In one of my first projects, a warehouse in Coesfeld-Lette, north Germany, we regarded the various facades as pictures and designed special gates that represent a mechanical sculpture. In later buildings, too, I always tried to incorporate something of my sculpting activities.
Detail: Could one regard your structures as built sculptures, then?
Calatrava: One thing to be learned from the past is that architecture can avail itself of the other arts. A Gothic facade serves above all as a vehicle for sculpture. The entire architecture of the Sistine Chapel is aimed at accommodating the painting. It seemed to me that I could use the three-dimensional expression of my sculptures in a similar way: to develop a vocabulary in architecture. Initially, this had a very formal interpretation, masked a bit perhaps by a sense of the flow of forces. Later, I witnessed how it became a trend to regard architecture as sculpture. I sensed how
Alexander Calder, Jean Dubuffet and Henry Moore must have felt an enormous craving for architectural forms in their last works.
That means, of course, that architecture can be assessed by the criteria of sculpture. I can interpret the language of certain sculptors with the eyes of an engineer: Alexander Calder welded metal sheeting; he used rivets and sheet metal that he bent to form. In the final analysis, he availed himself of the language of engineers to find the appropriate expression.
Detail: Why did you study engineering after your architectural studies?
Calatrava: To be quite honest, I didn’t want to enter into the stark reality of professional life at the age of 23. So I went on to study structural engineering at the ETH [in Zurich]. After completing my dissertation, I won the competition for the Stadelhofen railway station, together with a colleague, as a result of which we had seven years’ work.
Detail: Today, you have a number of offices in different parts of the world. Is the one in Zurich your headquarters?
Calatrava: My offices in New York and Zurich are, in fact, the same size. I have one in Valencia as well, which is somewhat smaller at the moment. Altogether there are about 90 of us – engineers and architects.
Detail: And you always cover both fields: architecture and structural engineering?
Calatrava: As a rule, we do the structural engineering as well as the landscape architecture in-house. We also build the models ourselves and – at least at the preliminary planning stage – are concerned with the technical installations. I try to avoid the division of dis-ciplines. We don’t lead a double life, doing simple projects and occasionally something special.
Detail: You’ve remained relatively true to your architectural language from the very beginning.
Calatrava: I have always attempted to speak my own language, and I think that’s a right one has, even if some people may see it as a form of arrogance. I profit from teachers, of course, but ultimately my school is my own. I’ve studied Michelangelo and Borromini; I’ve ventured cautiously in the direction of Gaudi and visited Louis Kahn. As a student, I travelled a lot in the Mediterranean area and vis-ited the classical cities, but in the end I discovered that it’s important as an architect to come up with a statement of one’s own. That doesn’t mean a person can be entirely autonomous; one is constantly subject to outside influences. But I always had the ambition to bring my own ideas to fruition and to incorporate my own feelings in my buildings.
Detail: Does the fact that you’re an engineer, an artist and an architect give you greater independence?
Calatrava: My decision to move in many different fields is perhaps an expression of curiosity and the wish to explore things to the limit. I’ve always regarded that as a source of innovation.
Detail: Even so, a building structure obeys different laws from a pure sculpture.
Calatrava: What makes architecture special is its functional aspect. It plays a serving role; it has to be useful. It is subject to constraints with which a sculptor is not concerned. On the other hand, that’s precisely what makes architecture exciting: it’s where its philanthropic secret lies. If architecture plays a functional, serving role, it enters into a relationship of love – with people in general and with the designer, as well. That’s something I find very beautiful.
Detail: Your buildings often dissociate themselves from their surroundings.
Calatrava: Some buildings I have designed are detached from the context – usually because it was so ugly, as in the case of Lisbon station, which was erected on the site of a former oil refinery with polluted soil. The harbour area of Valencia is another example. There the ground was contaminated with pyrites and nitrates, and we had to rehabilitate it before we could begin to create a new urban district. When you work in a context like that, there’s not much to latch on to.
I have also built in impressive landscapes, though, such as the Spanish province of La Rioja. Close to Laguardia, I was able to erect a relatively large building for a winery in the midst of a wonderful rocky landscape. It was more or less an industrial structure that simply had to function properly. I was faced with the challenge of designing something that should be integrated as far as possible into the landscape. That was why I adopted the colours of the surroundings, using ochre and wood tones, together with grey aluminium, which corresponded to the colour of the rocks. Similarly, the roof form, which reflects one of my sculptures, makes reference to the surroundings. People who talk about environmentally friendly construction or sustainability shouldn’t think just in terms of the carbon footprint or energy efficiency, but of a respectful approach to the landscape, too.
Detail: Your building in La Rioja, Spain, differs from your other structures. For one thing, it’s not white. The colour white is another signal feature of your architecture.
Calatrava: My first building, the hall in Germany, was not white, nor was the station in Stadelhofen, which has a grey or anthracite appearance. I’ve also used green copper sheeting.
Detail: Nevertheless, you use a similar formal language for all kinds of developments: transport structures, such as airports, stations and bridges, or a grand opera house and a museum like those in Valencia.
Calatrava: All the buildings you mention are, in fact, formally quite different. In terms of colour, the structures in Valencia, which are part of an ensemble, may be similar. Formally, though, they are completely different. What links them is not so much the idea that I repeat elements from an architectural canon, but that I use the same materials: steel, concrete and a limited amount of glass, because the climate there is not particularly suited to large areas of glazing. Another common feature is the use of ceramics, whereby for cost reasons we resorted to waste ceramics. In spite of the low budget, the buildings had to have an emblematic function, which we achieved with the colour white, among other things. When I built my first bridges, white was unusual for structures of this kind. Today, one sees white bridges all over the place. Similarly, pure steel bridges were not common in those days. Composite forms of construction were more usual.
Detail: In our eyes, your great strength lies first and foremost in your transport structures. How does your approach differ from that to a museum or opera house?
Calatrava: I love music, and I find it congenial to build for that purpose. I had the opportunity to do so not just in Valencia, but in Tenerife as well. The concert ensemble there, with a large auditorium for 1,600 people and a smaller hall for chamber music with space for 400 concertgoers, cost €72 million. In other words, one can build something like that with limited resources. If I had the opportunity to construct an auditorium in Berlin, it would certainly turn out quite differently. In the case of the Milwaukee Art Museum, I was commissioned to design something that would define a quite specific identity, for the clients had accumulated sufficient funds from sponsors.
In principle, though, I don’t see why a station should be something completely different from a museum, or why a bridge in an urban situation should not have a bold character, too. Take Paris: if you were to remove all the bridges, it would be a totally different city. In other words, all structures have a significance. Exceptional railway stations make a stronger impact because one is more accustomed to smart looks for museums. Stations are normally regarded as places with a bad smell and where it can even be dangerous at times.
When I began to build bridges, they were purely functional structures. Everything was prefabricated, because all the bridges in Europe had been destroyed during the Second World War and they had to be reconstructed quickly. In the 1950s, therefore, the best bridge was the cheapest one. That’s why an unusual station or airport or an exceptional bridge attracts greater attention.
also concerned with hallmark architecture?
Calatrava: No. It has more to do with a personal attitude.
Detail: But some clients certainly say: “I want a Calatrava”, and they want it to have a particular look. You mentioned the Milwaukee Art Museum, where the clients wanted something quite special.
Calatrava: They would have got that from many other architects, not just from me.
Detail: Your buildings are very popular; some are even tourist attractions. What’s more important to you: the verdict of professionals or the satisfaction of the users?
Calatrava: I have great respect for architectural critics and conduct a dialogue with some who are friends of mine. When you sit in front of a sheet of paper and sketch something, though, you’re all on your own. The critics are far away; it’s not unlike the situation in which a painter finds himself. I’m sure Matisse didn’t think of the critics when he was painting, nor did Picasso.
Detail: How many sketches do you make for a project?
Calatrava: It varies. We’ve catalogued some 100,000 drawings from the past 28 years.
Detail: You still draw a lot by hand. What role does the computer play in your work?
Calatrava: We work a lot with the computer. In order to use computers in Europe at a relatively early date, I brought them in from Canada. In other words, I’ve been a computer user from the word go. But I can also design things without one. I would maintain that you can see whether something has been designed by hand or generated with a computer. As an aid to depicting something or as an interface with industry, the computer is indispensable today: think of the many sections a computer provides almost automatically during the detailed design stage.
Detail: Does the new scope provided by
the computer have much influence on your architecture?
Calatrava: I certainly create buildings that I could not implement without the computer. The bridge in Jerusalem, for example, would have been inconceivable without one – especially the calculations. But I don’t let the computer generate stochastic images and then translate them into spatial form. I prefer to take an orchid or a beautiful snail’s shell as a model. The fantastic quality of such forms has a logic of its own and is far more convincing than something developed with a computer. I have absolutely nothing against the computer, but at that point where the form is defined, I wouldn’t like to use anything but my own hand. This relationship between me and the object is something I don’t want to give up.
Detail: One might think that a building like your station in Liège wouldn’t have been possible ten years ago. But you began the planning as early as 1996. Would the form have been feasible without computer technology in that case, too?
Calatrava: Yes, certainly. But the mathematical analysis of the building would have been very difficult without the computer – in respect of its dynamics and the structural calculations. The girders are very, very slender, but they could certainly have been drawn by hand.
Detail: What was the reason for the unusual direction of span of the arch elements in the hall roof – parallel to the tracks?
Calatrava: All the tracks were to be kept in operation during construction. We therefore built an additional track so that we could close one down at a time and renew it. The longitudinal direction of the arches was very practical for this conversion process. As the work progressed, we could push the roof laterally over the tracks. Secondly, Liège is an important transport node in Europe, through which a lot of long-distance routes run to major cities. This justified the construction of a large, quite special station. What’s more, the form selected for the roof echoes the line of the nearby hills of the fashionable villa district of Cointé. Since the railway lines had divided the city, we wanted to create a certain permeability and transparency between the areas in front of and behind the station. We couldn’t have done that with arches in the lateral direction. It was also my aim to accommodate the trains – roughly 220 –240 metres long – entirely in the station hall. Only extra long trains extend out beneath the platform roofs.
Detail: Apart from formal goals and urban-planning considerations, did the underlying logic of the structure itself have an influence on the ultimate form?
Calatrava: It’s good when several things come together. The structure is quite daring. It has a height of less than 1.20 m at the crest, with a span of roughly 160 m. The ratio of thickness to span is, therefore, greater than one to a hundred. There’s no wind bracing either. Everything was braced by restraining the pur-lins through the steel connections.
Detail: Isn’t that rather elaborate. Wind bracing would certainly have been simpler and more economical.
Calatrava: Because of the many connections, the roof has great structural indeterminacy. That’s why it has the behaviour of a planar bearing structure, although it’s actually not one. Bracing would have created problems with expansion. The form of execution is simple and functional. The flexurally rigid connections weren’t the most complicated, because they are relatively high. They could have been implemented with high-strength bolts instead of welding, but they would then have had to comply with very tight tolerances.
Detail: Did details play an important role?
Calatrava: Certain details were decisive; for example, the pyramidal hinged joints at the base of the arches, where cast elements and a visible chromium-steel bolt were used. The latter demonstrates that this is a hinge. At the transition from the arches to the longitudinal girders that support the two galleries, there is an extremely complex steel structure. We sought to minimize details of this kind. With the great spans involved here and in view of the limited funds available, we had to find compromise solutions at certain points. Some of the details were created on the spot. We had a lot of problems with the tolerances for the aluminium glazing sections. There are great differences between the tolerances for glass-and-aluminium construction on the one hand and large-span steel structures on the other.
Detail: Are the entire compression loads from the arches transmitted at the bearing points, or are there tension elements that tie the ends of the arches together?
Calatrava: The counter-cantilever balances out a small proportion of the loads. There’s also a counterforce in the pyramidal bearings; but the horizontal load component from the main arches is much greater. It is balanced out by the steel structure to the galleries and distributed to the various bearing points, but the concrete elements between the ends of the arches were prestressed, and there is a continuous lower connection.
Detail: Was the main purpose of the shopping arcade below the platforms to introduce daylight?
Calatrava: Providing daylight was very important to us, but there was a further aspect. As a result of the high-speed link between Liège and the centre of Brussels, with a journey time of 35 minutes, this has become virtually an inner-urban trip. People don’t want to be held up very long before they board their train, therefore. For that reason, we wished to create a station with a sense of immediacy. That gave us the idea of a station without a facade, which results in a through draught, of course. The shopping arcade was meant to offer a certain comfort, therefore, and to serve as a waiting area, too. The operators themselves were interested in a special arcade and wanted to use local material. We thus had an opportunity to install a fine floor finish. We used a black stone, known there as “petit granit”, but which is, in fact, a limestone. It lends the station a certain dignity. Via the underground arcade, one can reach the right section of the trains very easily.
Detail: How many projects are you working on at present?
Calatrava: At the moment, I’m working on a project for Taiwan, which involves three smaller structures for a university, including a concert hall. Then I’m concerned with a museum in Rio de Janeiro, where we’re still only at the beginning. We’re involved from time to time with the airport in Denver – in a series of steps; and finally, there’s Ground Zero in New York, which is an extremely bold scheme. The entire development is underground, with spans of 70 metres. There’s an element of Liège about it, with linear load-bearing systems that are very effective. It has been shown that clarity and transparency in halls of this kind are good for security: firstly, because people can find their way about quickly, and secondly, because fewer cameras are needed for observation, which allows very open spaces to be implemented.
Detail: How is the design process for your projects – which you begin with your drawings – continued in the teams?
Calatrava: Shortly before you came, we were discussing the sketches I had made over the weekend; and we held a video conference with New York about the small project in Taiwan. As a communication system, we use corrections made on plans or sketches.
Detail: Do you monitor every project down to the final details?
Calatrava: I’m the architect who designs all the projects, and I follow them through, if possible, down to the details. I have a very good team of assistants, of course, which allows me to work in this way.
Detail: In what phase of a project do you feel the greatest personal satisfaction?
Calatrava: The sketching stage is, of course, extremely congenial. Our projects are very labour-intensive. Liège, for example, took 13 years to complete, so one needs enormous patience. We’ve been working on the Ground Zero project for eight years, and now I receive news that the differences between the clients are still too great. Making progress in a scheme is sometimes quite arduous. In comparison, making sketches is very pleasurable.
Detail: One final question: which of the structures you have created is most satisfying to you?
Calatrava: I’m very fond of Liège, and I’m happy that you have devoted so much attention to it. If I could begin all over again with the planning, maybe the outcome would not be the same. When I’m there, I sometimes think that the ramps are too wide, and perhaps I’d choose a larger span today. But the overall impression is right. Ultimately, it’s clarity I’m always looking for. That’s what counts in situations like this.
