To Engineer Is Human Page 8
As the nineteenth century drew to a close, the situation in Britain was apparently no different, as a macabre pencil drawing by John Tenniel, the illustrator of Alice’s Adventures in Wonderland, suggests. His drawing of Death straddling the cracked girder of a railway bridge and captioned “On the Bridge!” appeared in an 1891 issue of Punch. The image was used to illustrate an anonymous essay with the same title, which, as its introduction stated, was meant to be a modernized version of Joseph Addison’s “The Vision of Mirzah” (which had appeared in a 1711 issue of The Spectator). In Addison’s allegory, the narrator Mirzah is led by a genius to a precipice above the valley of time that is spanned by a bridge, which represents human life, linking the beginning of the world and its end. The bridge Addison’s Mirzah observes is in a ruinous condition, and many attempting to cross fall through. Mirzah passes some time marveling at the wonderful structure, but his heart fills with “a deep melancholy to see several [human figures] dropping unexpectedly in the midst of mirth and frivolity, and catching at everything that stood by them to save themselves.”
Addison goes on to moralize, and so in his own way does the anonymous Punch parodist. In that modernized version, the protagonist, Matthew, contemplating “the Vanity of human Holiday-making,” falls asleep over the pages of the multitudinous timetables of Bradshaw’s Monthly Railway Guide. He dreams of being taken by a Genius to a pinnacle above “the Vale of Travel” traversed by “the great Railway System,” which rises out of and recedes into the mists of “Monopoly and Muddle.” The Genius directs the nineteenth-century Mirzah’s attention to a metal bridge, of which Matthew reports:
I found that the arch thereof looked shaky and insecure; moreover, that a Great and Irregular-shaped Cleft or Crack ran, after the fashion of a Lightning-flash in a Painted Seascape, athwart the structure thereof from Keystone to Coping. As I was regarding this unpleasing Portent, the Genius told me that this Bridge was at first of sound and scientific construction, but that the flight of Years, Wear and Tear, vehement Molecular Vibration, and, above all, Negligent Supervision, had resulted in its present Ruinous Condition.…
Only an Attent, and, as it were, complacently Anticipative Visage, of an osseous and ogreish Aspect, gleamed lividly forth therefrom, as the Apparition appeared to Look and Listen through the Mist at one end of the Bridge for the welcome Sight of Disaster, the much desired Sound of Doom. A shrill and sibilant Metallic Shriek seemed to cleave the Shadows into which the Spectre gazed; a Violent Vibratory Pulsation, as of thudding iron flails threshing upon a resonant steel floor, seemed to beat the Roadway, shake the Bridge, and as it appeared to me to widen the levin-like Crack which disfigured the Arch thereof.
When Matthew asks the significance of the Spectre, the Genius replies gravely that it is “Insatiable Death waiting for Inevitable Accident.” When Matthew asks about Monopoly and Muddle, the Genius is no longer found present. Matthew soon awakens and changes his mind about a “Railway Excursion to Rural Parts” for Holiday. Instead he goes to the pub and passes the day “in Safety—and Solitary Smoking!” (an as yet unacknowledged Victorian health hazard). The Punch story ends: “Next morning, however, I read something in the papers which led me to believe that Railwaydom Aroused meant exorcising and evicting that Sinister Spectre, ‘regardless of Cost’; and I shall look forward to my next Holiday Outing with a mind Relieved and Reassured.”
This suggests that even the railway companies themselves recognized the unacceptable frequency of bridge failures, but what the exact number was is a historical detail. Regardless of the numbers, the Punch parody and the drawing by Tenniel—like Nathaniel Hawthorne’s earlier short story alluding to unsafe bridges on the Celestial Railroad—demonstrate that the perceived risk of failure, and not only of iron truss bridges, was certainly high.
Our own contemporary technological failures perhaps bring this point home more forcefully. It took only a single DC–10 crash in Chicago in 1979 to ground the whole fleet, and the tragedy of the collapsed walkways in the Kansas City Hyatt Regency Hotel in 1981 was not diminished because it was a unique accident. Dismissing the single structural failure as an anomaly is never a wise course.
The failure of any engineering structure is cause for concern, for a single incident can indicate a material flaw or design error that renders myriad apparent structural successes irrelevant. In engineering, numbers are means, not ends, and it ought rightly to have taken the failure of only a single bridge to bring into question the integrity of every other span. This elementary observation was accessible to monarch and commoner alike in the nineteenth century, as the record of that period shows. Today we speak of “technological literacy” and the need for non-engineers to be able to understand the ways and methods of technology. Neither Queen Victoria nor the nineteenth-century railroad traveler seemed to feel intellectually timid in the face of the technical issues of their day, and their example is a good one for twentieth-century citizens. While some of the details of engineering may be arcane, the principles of design and safety, of risk and benefit, are not, for to build a bridge is no less a human endeavor than to take a trip. The common expectation of engineer and layman is that the road will not lead to bridges that collapse.
Which innovation leads to a successful design and which to a failure is not completely predictable. Each opportunity to design something new, either bridge or airplane or skyscraper, presents the engineer with choices that may appear countless. The engineer may decide to copy as many seemingly good features as he can from existing designs that have successfully withstood the forces of man and nature, but he may also decide to improve upon those aspects of prior designs that appear to be wanting. Thus a bridge that has stood for decades but has developed innocuous cracks in certain spots may serve as the basis for an improved design of a bridge of approximately the same dimensions and traffic requirements. Or an existing design that has suffered no apparent distress after years or decades of service may lead the engineer to look for ways to make it lighter and thus less expensive to build, for the trouble-free prototype appears to be overdesigned.
The choices of design are ultimately like the choices of life. While the engineer can pursue on paper two or even many different designs that fulfill the requirements of a projected structure, in the last analysis only one design can be chosen to be built, just as, finally, only one route can be taken on a single trip from Chicago to New York no matter how many are considered in the planning. Deciding which paper design will be cast in concrete presents the designer or the selection committee with a problem not unlike that faced by Robert Frost:
Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;
The designer tries to look ahead to determine where his different designs will end up down the road, but the way through the future always seems to fork again and again and to become fuzzy in the undergrowth. An ultra-conservative engineer may take the path that others have taken and opt for the familiar bridge, even though it is more expensive than a newer design or despite its unattractiveness for the site. A bold and imaginative engineer can infuse a bridge with meaning, as Frost did a common fork in the road. Robert Maillart, the Swiss engineer who has been called a structural artist, developed innovative concrete designs of both economy and beauty that revolutionized bridge construction early in this century, and he might be said to have followed the poet:
Two roads diverged in a wood, and I—
I took the one less traveled by,
And that has made all the difference.
7
DESIGN AS REVISION
There is a familiar image of the writer staring at a blank sheet of paper in his typewriter beside a wastebasket overflowing with crumpled false starts at his story. This image is true figuratively if not literally, and it represents the frustrations of the creative process in
engineering as well as in art. The archetypal writer may be thought to be trying to put together a new arrangement of words to achieve a certain end—trying to put a pineapple together, as Wallace Stevens said. The writer wants the words to take the reader from here to there in a way that is both original and familiar so that the reader may be able to picture in his own mind the scenes and the action of the story or the examples and arguments of the essay. The crumpled pages in the wastebasket and on the floor represent attempts that either did not work or worked in a way unsatisfying to the writer’s artistic or commercial sense. Sometimes the discarded attempts represent single sentences, sometimes whole chapters or even whole books.
Why the writer discards this and keeps that can often be attributed to his explicit or implicit judgment of what works and what does not. Judging what works is always trickier than what does not, and very often the writer fools himself into thinking this or that is brilliant because he does not subject it to objective criticism. Thus manuscripts full of flaws can be thought by their authors to be masterpieces. The obviously flawed manuscripts are usually caught by the editor and sent back to the author, often with reasons why they do not succeed. Manuscripts that come to be published are judged by critics and the general reader. Sometimes critic and reader agree in their judgment of a book; sometimes they do not. Positive judgments tend to be effusive and full of references to and comparisons with other successful books; negative judgments tend to be full of examples demonstrating why the book does not work. Critics often point out inconsistencies or infelicities of plot, unconvincing or undeveloped characters, and in general give counter-examples to the thesis of author, editor, and publisher that this book works. In short, the critic points out how the book fails.
The point was made quite explicitly in a recent review of The Man Who Could See Through Time, a play by Terri Wagener in which a physics professor and a young sculptor debate science and art. Reviewing the play in The New York Times, Frank Rich wrote:
The best two-character plays look so effortless that we tend to forget how much craft goes into them.… To see a two-character play that fails, however, is to appreciate just how difficult the form really is.
And so it is with engineering structures. The great suspension bridges look so simple in line and principle, yet the history of failures of the genre has demonstrated that their design takes a touch of genius. And geniuses like Washington Roebling and Othmar Ammann can arguably be said to have learned more what not to do from the great failures of their forgotten predecessors than today’s designers can be expected to learn about how to design the next suspended masterpiece from either the Brooklyn or the Verrazano Narrows Bridge.
Some writers, even if they do not try to publish them, do not crumple up their false starts or their failed drafts. They save every scrap of paper as if they recognize that they will never reach perfection and will eventually have to choose the least imperfect from among all of their tries. These documents of the creative process are invaluable when they represent the successive drafts of a successful book or any work of a successful writer. What other authors tend to learn from the manuscripts and drafts of the masters that cannot be learned from the final published version of a work is that creating a book can be seen as a succession of choices and real or imagined improvements. An opening sentence or even a word may evolve to its final form only after going through dozens of rejected alternatives. Sometimes the final version is closer to the first than any of the intervening versions, and sometimes a word will be crossed out only to have a ladder of synonyms, near synonyms, remote synonyms, and even antonyms leading like Jack’s beanstalk through the clouds of imagined riches, ultimately to have the author fall back on the very word with which he began. These creative iterations suggest that the author’s choice of even a single word is more easily understood in terms of rejection than acceptance, in terms of failure rather than success, in terms of no rather than yes. The fair manuscript gives little if any hint as to why exactly the author put down what he did in his first draft. But the word changed, the sentence deleted, and other alterations that may be traced through successive drafts show clearly that the author did not believe what he had originally written had been right. It failed in some way to contribute to the end that the author was working toward. This is not to say that something unchanged from first to last was deemed perfect by the author; it simply indicates that, rightly or wrongly, he detected no unacceptable fault with it or could see no alternative. The unchanged part of his book’s structure might teach the student nothing about its composition, however.
Some of the acknowledged masters of the written word were seemingly never completely satisfied with their work. James Joyce was apparently notorious for making voluminous changes even as his major works Ulysses and Finnegans Wake were being set in type by the printer. And what was set in type was revised by Joyce in the proofs. In 1984, after volumes of criticism were published based on the original 1922 version of Ulysses, a new edition appeared, reportedly correcting over five thousand errors that crept into the first edition. The book was claimed by one critic to be so changed by the restoration of a few dropped lines that a whole new interpretation of the novel was in order.
Other recognized masters often express the thought that they abandon a work rather than complete it. What they mean is that they come to realize that for all their drafts and revisions, a manuscript will never be perfect, and they must simply decide when they have caught all its major flaws and when it is as close to perfect as they can make it without working beyond reasonable limits. Even the twenty-odd years Joyce spent on Finnegans Wake was apparently not enough for him to believe he gave a perfect manuscript to the printer, and all authors acknowledge implicitly that revisions to manuscripts reach a point of diminishing returns.
The work of the engineer is not unlike that of the writer. How the original design for a new bridge comes to be may involve as great a leap of the imagination as the first draft of a novel. The designer may already have rejected many alternatives, perhaps because he could see immediately upon their conception that they would not work for this or that reason. Thus he could see immediately that his work would fail. What the engineer eventually puts down on paper may even have some obvious flaws, but none that he believes could not be worked out in time. But sometimes even in the act of sketching a design on paper the engineer will see that the approach will not work, and he crumples up the failed bridge much as the writer will crumple up his abortive character sketch.
Some designs survive longer than others on paper. Eventually one evolves as the design, and it will be checked part by part for soundness, much as the writer checks his manuscript word by word. When a part is discovered that fails to perform the function it is supposed to, it is replaced with another member from the mind’s catalog, much as the writer searches the thesaurus in his own mind to locate a word that will not fail as he imagines the former choice has. Eventually the engineer, like the writer, will reach a version of his design that he believes to be as free of flaws as he thinks he can make it, and the design is submitted to other engineers who serve much as editors in assessing the success or failure of the design.
As few, if any, things in life are perfect, neither is the analogy between books and engineering structures. A book is much more likely to be an individual effort than is a building, bridge, or other engineering structure, though the preparation of a dictionary or an encyclopedia might be said to resemble the design of a modern nuclear power plant in that no individual knows everything about every detail of the project. Furthermore, the failure of a book may be arguable whereas the failure of a building collapsed into a heap of rubble is not. Yet the process of successive revision is as common to both writing and engineering as it is to music composition and science, and it is a fair representation of the creative process in writing and in engineering to see the evolution of a book or a design as involving the successive elimination of faults and error. It is this aspect of the analogy that is most
helpful in understanding how the celebrated writers and engineers alike learn more from the errors of their predecessors and contemporaries than they do from all the successes in the world.
While engineers who play it safe and copy designs that have stood the test of time may be well paid (though perhaps not nearly as well paid as the authors of mass market paperbacks who use more formulas in their genre fiction than are available to any engineer), there is no more professional distinction in being such an engineer than there is literary recognition in being such an author. When we speak of creative engineers we are talking about as select a few as there are great writers. And just as the great writers are those who have given us unique and daring experiments that have worked, so it is that the great engineers are those who have given us their daring and unique structural experiments that have stood the test of time.
It is not capricious to compare engineers with artists on the one hand and with scientists on the other. Engineering does share traits with both art and science, for engineering is a human endeavor that is both creative and analytical. Being creative pursuits, the innovative works of engineering test the vocabulary of the critics, whoever they may be, and it is not always clear-cut whether a daring new structure will stand or fall, even in the make-believe world of hypothesis testing. The problem with the new structure lies in the very humanness of its origins and of the world in which it will function. Whether an engineering structure succeeds as a work of art may not be a question of life and death, but whether it will stand or collapse beneath the weight of those attending the dedication ceremonies is indeed a question to be reckoned with.