One On One, Part II; No. 7; What Makes Bridges Stay Up and Fall Down, Featuring Dr. David Billington

This program is made possible by a grant from Sigma Xi, the scientific research society. Traffic is heavy most of the time on the Mayanis River Bridge here in Connecticut, although several years ago something happened to change that, and most residents can't forget it. Part of this bridge fell down late one night, just like that, and people were killed. Now understanding these big structures is very important. I'm Faith Middleton, and my guest is David Billington. He'll tell us why bridges stay up or fall down, and why they are for him works of art. This is one-on-one. David Billington wrote the book The Tower and the Bridge. He teaches engineering at Princeton University in New Jersey, and when you listen to him, you learn pretty fast that engineering affects most of what we do every day.

Now before the Industrial Revolution in the late 18th century, there was no way to build anything out of metal. But then industrialized iron was introduced, and that gave us bridges, machines, and all these buildings. There's plenty to talk about, but when I met David Billington, I knew he'd want to start with beauty. Certainly, a great many bridges are, in my view, beautiful. They are, in fact, works of art. In particular, the bridges of one man, the Swiss engineer, Robert Mayar, has engaged my attention now for about 20 years. And I think his works are the most beautiful of this art for. I know you mentioned the word art. Do you think engineering is an art? Well, I think that I have argued in my recent book, The Tower and the Bridge, that structural engineering at its best, is an art form.

It's a new art form that came into being only with the Industrial Revolution and these new materials. And there has existed over the past 200 years, a tradition of this art form, carried on by a series of great engineers who considered themselves artists, and who were quite conscious of the fact that they were designing on the basis of three separate ideals, which are which are first efficiency, that is to say, all things being equal, the structure that uses the least amount of materials is automatically the best, so long, of course, as it is safe. You can use two smaller material and it'll fall down, and then it, of course, means nothing. So that's the first ideal is efficiency. And did they ever fall down? Well, the best engineers, of course, their works have not fallen down. There are many other works, unfortunately, that did fall down, a very tiny percentage, but a rather large number, and some very famous ones, such as the so-called galloping

girdy, the Tacoma Narrows Bridge, in Tacoma, Washington, which collapsed in a windstorm in 1940, and for which there is a spectacular movie. Many people have seen that movie. And I'm thinking about, in Connecticut, the heart perspective, where all the heart for a civic center collapsed, and the Mayanas Bridge collapsed in Connecticut, that's correct. And so there are, of course, there are hundreds of thousands of bridges, and only a few have failed, but still they are quite famous, and it is important for engineers to know why they have failed. So the first ideal is minimum materials, consistent with safety. The second ideal is economy, and since these structures cannot exist without society, that is to say, engineering is a social process. It must come into being only with lots of people involved, and lots of money involved. And therefore, the second ideal for the engineer is to get the things actually built, and to do that, they must be economical, but they also must serve their purpose.

So the use of minimum monies goes together with the goal of there being useful. So engineers are supposed to say, let's do it the cheapest way possible, and still maintain quality. And still maintain the quality that needed for the usefulness. That's right. So that's the second ideal. First ideal minimum materials, second ideal minimum money, but that's never enough. There has to be a third ideal, and that's where the individual comes in, because the great works, the greatest works of structural engineering are the products of an individual personality. That's why I focus on individual people, such as John Robling, designer of the Brooklyn Bridge, Gustav Eiffel, designer of the greatest bridges in the 19th century in Europe, and also, of course, his famous tower in Paris. And then modern engineers like Robert Mayar and Switzerland, and Ottomar Amman, who also Swiss, who designed most of the large bridges around New York, the gold, George Washington

Bridge, and so forth. So are you saying a committee of people never designed a great? It's the same way with a poem. Very few poems of quality are designed by committee, and very few great works of structural art are designed by committee. Is it hard to build a bridge? Well, the answer, of course, is yes and no. Modern bridges are built by rather careful techniques developed over several hundred years, and so that process was difficult to develop, and lots of trial and error. The other hand, for many bridges today, particularly typical overpasses and all, they are built rather, rather quickly, and rather easily now. So one could say that standard bridges are reasonably easily built today, large-scale bridges such as the Golden Gate Bridge or the Verazzano Bridge, of course, they are very big challenges

to build. They still are today. They still are today, of course, because they are huge things. Are they meant when they're built to last forever? Well, yes and no, yes they are meant to last for as long as they are properly cared for. All of these works must be maintained. The Eiffel Tower would rust away in several generations if it wasn't continuously painted. They're subject to all kinds of weathering. But if they are carefully maintained, there is no reason why they should not last. Well those remarks about maintenance seem obvious, but is it something we really know as a society, though? I mean, do we pay attention to those rules? No, we certainly don't. We certainly have not. We have been engaged in the last 200 years in building, particularly in the United States, and to a lesser extent, but still in Western Europe. And the excitement has always been the new, building something new.

And the attitude, at least in this country, has often seemed to be, well, if it's old, then we'll scrap it and build something new. And we are only gradually coming to realize that we can't afford to do that anymore. And that we have to try to build with a longer future in mind. And indeed, one of the greatest contemporary bridge builders has proposed the idea that every bridge should come with a manual of operation that the owner gets from the designer, just like you get from a car, for a car. And that tells you what you're supposed to do, what kind of inspections you're supposed to have every six months, every year, every five years. You mean that doesn't exist? That doesn't exist, no. And how does the information get passed on? Well, I mean, who knows how to care for the Golden Gate Bridge or the Brooklyn Bridge? Well, there are, of course, public officials charged with that activity. Images are normally the province of states, and there are state highway departments.

And their job is to maintain these bridges. They have that clear and distinct obligation. But unfortunately, they are largely underfunded, and they have built so many bridges, and they have usually such a small staff that they can't possibly follow a reasonable maintenance schedule. And so much of their work has to be to go for the things that are just about ready to go rather than systematic careful inspection. Are we in danger at some point of seeing a major bridge collapse? That's unlikely, very unlikely. I think the miasna bridge that fell in Connecticut whenever it was 83, I think, was a way of major bridge. I mean, it was certainly on a major artery, and fortunately, it came down, at least relatively speaking, when there were very few very little traffic.

But it sent a signal, though. It certainly sent a signal for bridges. It's not a long-span bridge. I mean, there are thousands of bridges of that kind of size. And it certainly sent a signal for such bridges. The major bridges, such as the bridges in New York City, the Manhattan bridges, are all now undergoing major renovation. And none of them, as far as I know, were actually in danger of collapsing. But they were all certainly badly in need of maintenance, very badly in need. And had there been no maintenance program, they would surely have collapsed eventually, not too long, not too distant future. How do you build a bridge? I don't know. Imagine the Veritsano bridge, for example, big bridge, Veritsano bridge. And the first step in such a bridge is of the major superstructure is to sink the case ons for the two towers.

And that's a big project in itself, mostly done underwater. And then the towers are built up in the air on top of each other. That is to say, you build it up by building on top of what you've already built, to you get way up in the air with the towers. The two towers of the Veritsano bridge are not parallel, incidentally. They are sloped with respect to each other because of the curvature of the earth. So they're further part of the top than they are at the bottom. And then the next job is to prepare the foundations on the shore for the anchor reaches of the cables. Then the cables were strong from anchor reach over the top of the towers, sagging down to the middle of the span, and then back to the other shore, over the tower and back to the other shore. Once the cables are up, then the deck is hung from the cables. And with the deck hung and secured to the approaches on either side and to the towers, then the roadway is paved and the bridge is opened. Sounds easy enough.

Sounds easy enough. Takes a few years, several hundred millions of dollars, thousands of people, and hundreds of people, maybe not always thousands, but that's a big example, of course, but they're much simpler bridges than that. Do you have to understand numbers? Well, if you speak of the engineer or you speak of the general public, I think if the general public wants to understand about bridges, they need to understand three kinds of things about the bridges. And I'm referring now to, for example, to courses that I teach at Princeton for liberal arts students who study these subjects without technical background. And in order to understand how bridge works, they still need to know a few formulas and to work with a few numbers. That's crucial. They don't have to have calculus or higher mathematics or college physics, but they do need to work with a few numbers.

The second idea in... Excuse me. One of the numbers tell me why the form looks like it does. Imagine the Eiffel Tower. Why does that form look like it does? Well, you want to know that at the halfway point of the tower, the width of the tower is just about one quarter, the width of the base. So you have a curve, you have two curves converging, and at the base it is four times as wide as it is halfway up, and then it is almost zero at the top. Now that's the curve of a parabola. And what is a parabola mean? That means that if you take the wind load, the horizontal blowing wind against the tower, which is what the tower is designed for. That's the principle load on the tower. That the way the engineer defines the forces in an object like a flagpole or something sticking up in the air called a candle lever.

When they figure out the forces against a candle lever, it turns out that the forces at the base are four times as great as they are halfway up. So the structure should be four times as wide as it is halfway up. So those are the kinds of numbers, and a simple expression, a parabola is an easy expression to write, the formula for it, and you can see that the formula for the wind effects is also parabolic, and therefore you can connect together the loading and the four. I got it. Okay, so you were saying three, there are three things. So first is that expression of numbers, but the second thing you have to understand is is the historical context in which something arises, and the controversies and the politics that surrounds it, because these works are always political objects. And therefore the public always is involved in paying for them, in objecting to them, in liking them, in using them, and so forth.

For instance, in the case of the Eiffel Tower, the many of the most elite public thought that that was a monstrosity to build that in Paris. When they first saw Mr. Eiffel's proposal, they wrote it to the mayor of Paris and said, you can't possibly build that. It's a horrible thing. What do you think about that? And well, I think they were mistaken. I think they were their image of building was conditioned by pre-industrial revolution forms. They could only imagine city buildings as being heavy, stone, facade, solid buildings. Here was this light, transparent, metal structure. They had not yet brought their vision into even the 19th century. And so I think they were just mistaken. Of course, by now, I think there's ceases to be any argument culturally about the Eiffel Tower. That doesn't mean that some people still don't like it, but it does mean just like some people don't like Mozart, but the culture has ceased to argue whether it's great music

or not. And the same thing is true with the Eiffel Tower and the Brooklyn Bridge and the Bridges of Mayar and so forth. And the third, then, is that these works, of course, at their best, are works of art and as works of art, they are great symbols of the times in which they are built and they are consciously designed by individuals who think of themselves as artists. And so the third aspect is to understand these works as works of art, as a new art form, an art form that didn't exist before the Industrial Revolution, before the introduction of the new materials of industrialized iron and then steel and then reinforced country. Why is that important to you? The art. Well because I think that it's an expression of personality, it is sense in which it is the ultimate reason why engineering is a humanistic discipline as well as a scientific discipline. And it is important for engineers and the general public to understand what technology is best can be, just as it is important for people to understand poetry, to understand

what the language and best can be. And though the vast majority of things that are written just as the vast majority of things that are built are not works of art. If you've just joined us, we are with David Billington, who is an engineer and professor of civil engineering at Princeton University. Is there a style in bridges, summer, metal, and summer concrete? Yes. How do they decide? Concrete becomes competitive, more competitive, usually less expensive than steel, away from our major steel mills. In the east, there's more steel bridges in the far west and in the south. There are more concrete bridges. There tend to be, tend to be the case. There are many counter examples, but that's tend to be. Why did you become an engineer? Well I more or less backed into it. We had a special program at Princeton called Basic Engineering, which was a program for

people who wanted to take engineering, but probably didn't want to be engineers. And I took it because I could take a lot of liberal arts courses. I was interested in literature and art and music. And so I was able, by that program, to take more liberal arts electives than the liberal arts students. And then by good luck, I got a Fulbright fellowship to go study in Belgium in 1950 to study bridges in Belgium because, and frankly, my interest was I wanted to go to Europe. And the most, the way that looked, the only way looked possible for me was to get a Fulbright scholarship. They had just introduced the Fulbright program. And I tried to figure out a project that would be reasonable. And I got some good advice for one of my professors at Princeton. I had some knowledge of French, so I applied to go to Belgium, where the bridges had been blown up through, each bridge practically had been thrown, blown up three times during

the war. So they had developed techniques for building bridges very quickly. And the country, of course, it's the lowlands, and they tried to have to have their bridges through all the canals and little rivers and everything. So I went over there and studied for two years. And in that way, really learned structural engineering and became quite interested in it, yes. But I still did not have any sense of it as anything aesthetic. And I practiced engineering for eight years in New York, then came to teach. And it was only when I began to teach that, and particularly when I began to teach architects who were very bored with what I was teaching them, the straight engineering. And they would bring me pictures of beautiful things, and ask why they couldn't study those things. And they actually brought me my our bridge pictures, which I'd never seen before. So I agreed that they were beautiful, but I didn't know how they worked. And so I started to try to figure that out.

And that was what really got me going. And so that brought the two together, the art and the technology, well, it was the aesthetics. And I didn't know, think of it as an art form in those days. It just seemed to me they were very beautiful things. And I was interested in finding out whether they were good engineering. In other words, people were talking about my our bridges and other things as works of sculpture or as architecture or things like that. And so I began to study them carefully. I went to Switzerland, got the original drawings and calculations, and began to study these works. And I realized that they were not architecture at all. They were not sculpture at all. They were engineering, pure engineer. And the technical features of these works were far in advance, not only of their time, but of our time. And therefore I became more and more convinced that my art was an engineer, pure engineer. But he was also at the same time an artist. And he was conscious of that. He wrote like that. He wrote about aesthetics.

He wrote about the idea of engineering as not only technical but aesthetic as well. Do you want to build a bridge? No. No. I had a long enough experience working as a designer to know that I was not cut out to be a designer. Why not? Well I didn't have the right sense, inner sense of that. And I found out that I was much better as a teacher and a writer and a lecturer so that I have no illusions that I could really do that. When a bridge comes along, we hear the name of the engineer. But when buildings are all lined up, I never hear the names of engineers. Why is that? Well, the general view is that buildings are works of architecture. And I think in many cases that's a correct view, there are different building types and engineering and architecture are often confused together.

But as engineers aren't you the men and women who tell the architects why the building won't fall down? Well, yes, for large buildings. For small buildings, no. For a private house, for example, you don't need to have an engineer. The architect is normally well enough trained to be able to do the whole thing, all by all alone. As the building gets bigger and bigger, the engineering part of it becomes more and more important. And for a number of tall buildings, particularly those coming out of Chicago, the engineering becomes so important that the whole form becomes, in some cases, engineering form. And there are a few, very few engineers who have in fact become the designers of the form of tall buildings. Even though most tall buildings are not, the form is not given by engineers, but in some case it is. What does the future look like in engineering? If we start cruising through the trade journals?

Well, I think that's an important kind of a question to get right. And I think that we have over the last 200 years since the Industrial Revolution focused always on the future. We've always thought, well, what's next? What's coming around the horizon? What's new? And I really think that there's a fundamental reevaluation that we have to begin to make. We have built a tremendous amount of things. They are, in many cases, decaying. We must learn to maintain what we have to rebuild sensitively what we can't, we can no longer maintain. Rather than imagining that some brand new idea out there is going to radically change everything. Really in what's now called the infrastructure, that there are no really fundamentally new ideas that are going to rise with respect to sewage treatment and water and roadways and airports and all those things, they're all contained big problems that need to be studied

and need to be worked on as they are built already, rather than as if there was some kind of thing. Now with materials, I mean there was iron and steel and reinforced concrete and pre-stress concrete, the forms possible with those materials by no means been exhausted. There are many new possibilities. We have a whole new class of bridges being built in this country just now called cable stay bridges, very beautiful bridges, which there have been about something like 15 of them designed and under construction in the past a decade. Where is one going up now? Well the most recently completed one is over the Ohio River Huntington, West Virginia, a very beautiful bridge and another large one has just finished over the Mississippi River not far from New Orleans, the Lulong Bridge and there are many others around the country. So that there are, these are new in a way, they don't use new materials, the forms are new though and there are many new possibilities for new forms.

So for the future you say we have to concentrate on maintaining what we've got. That's a high priority, but there are also new forms to be explored just as in any other art form. And that's the fun. And that's also part of the fun, yes. But it's also trying to make do with what you've got is a very great challenge. It's not always so much an artistic challenge, although it can be in the rebuilding of certain things, sensitive. Nevertheless, it is quite a challenge because it fits in with part of the engineer's aesthetic, aesthetic, I mean the engineer's ethic, of trying to do with as little as you can, trying to waste as little as you can. But is the pool here sort of a new generation of engineers coming out saying, I want to make my mark, I want to build something from scratch, I want to try my hand at a new structure. Is that kind of fighting against maintaining the old? There is some of that. On the other hand, along with the idea of maintenance, I think, goes the great importance

of studying history, that the modern engineer needs to know history. And needs to know when I say history now, I'm talking about the last 200 years. How these things came into being, because how these great works came into being is how the future works will also come into being. And by studying the history, one would also find that the great engineers of the past, those who built these great works of art, did their best works only after long years of experience, often with maintaining things and building things that were not so exciting. My art was 58 when the Saugena Tobel Bridge was completed, and he still had his best works yet to come. And Aman, who did the Veritsano Bridge when he was over 80, and so that the idea that you're going to go right out and design something new in this kind of field is not correct, usually.

Princeton University engineer David Billington, author of The Tower and the Bridge. One-on-one is a production of Connecticut Public Radio. The series is made possible by a grant from Sigma Xi, the scientific research society. For a cassette copy of the conversation you just heard, call 203-527-0905, or this member station of the Public Radio network. The engineer of one-on-one is J. McDermott. Michelle Press and I co-produced the show. I'm Faith Middleton. Thanks for listening.