Engineers of Dreams: Great Bridge Builders and the Spanning of America

by Henry Petroski

  By the turn of the century, tunnel projects in and around New York were inextricably associated with the names of William Gibbs McAdoo, an entrepreneurial lawyer from Georgia, and Charles Matthias Jacobs, a Yorkshire-born, privately tutored, and apprentice-trained engineer who had come to America in 1889 and subsequently designed tunnels for rapid transit and gas lines under New York’s East River. An exact contemporary of Lindenthal’s, Jacobs had become involved with Hudson River tunnels in 1895. As Jacobs and McAdoo were demonstrating the feasibility of tunneling under the Hudson, electric-traction locomotives were being developed, obviating the objection that smoke would choke passengers in the tunnels. Thus the Pennsylvania Railroad decided to build its own rail tunnels under the river, thereby removing themselves as the most significant potential supporter of Lindenthal’s bridge. In the meantime, over the past decade, Lindenthal had become established and well known as a consulting engineer in New York. In 1902, he found himself appointed by reform mayor Seth Low as the city’s commissioner of bridges; this necessarily redirected his attention from the North to the East River, which was contained wholly within the city of New York. But intracity and intrastate politics could complicate bridge design and construction at least as much as interstate issues.

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  Even before the Brooklyn Bridge was formally opened in 1883, there were calls for additional bridges between Manhattan Island and Long Island, on which the then separate city of Brooklyn was located. A new bridge was proposed to connect New York with Brooklyn’s Williamsburg section. Another was proposed farther north; here the presence in the river of Blackwell’s Island reduced the size of spans needed, while an approach convenient to Brooklyn’s City Hall was still possible. A charter for a Williamsburg bridge was obtained in 1892 by Frederick Uhlmann, whose interest appears to have been in extending the Brooklyn elevated railways into New York; this would have been a lucrative endeavor, given the congestion on the nearby Brooklyn Bridge, which was being loaded to its limit. When an East River Bridge Commission was formed, it bought out Uhlmann’s charter and appointed L. L. Buck as chief engineer to design a bridge capable of carrying an elevated railway as well as trolley cars.

  Leffert Lefferts Buck was born in Canton, New York, in 1837 and received bachelor’s and master’s degrees from the local college, St. Lawrence, before attending Rensselaer Polytechnic Institute. He graduated in 1868, his studies having been interrupted by the Civil War, which he entered as a private in the Sixtieth New York Infantry. After a period as assistant engineer on New York’s Croton Aqueduct project, he worked on railroad bridges and other engineering projects in Peru, Mexico, Aruba, and many locations around the United States. He oversaw the rebuilding of various parts of Roebling’s Niagara Gorge Suspension Bridge during the period 1877—1886 and, later, its replacement with an arch, which had superseded the cantilever proposal. He became chief engineer of the Williamsburg Bridge project in 1895 and would continue in that capacity until the bridge was opened in 1903 as the largest suspension bridge in the world, with a central span of sixteen hundred feet—four feet six inches longer than the Brooklyn Bridge. Its approaches were to be so long that the entire length of the bridge would stretch for seventy-two hundred feet, between Clinton Street in Manhattan and Roebling Street in Brooklyn.

  Leffert L. Buck, chief engineer of the Williamsburg Bridge (photo credit 4.12)

  When plans for the Williamsburg Bridge were first published in Engineering News, in 1896, it was criticized “from an aesthetical point of view,” and there appeared to be considerable visual discontinuity associated with the roadway at the towers, which were nothing like the monumental stone towers of the Brooklyn Bridge. Indeed, the shift at the towers from an above-deck truss to an under-deck truss made the truss itself look as if it had been severed by some angled guillotinelike device. In spite of this image, Buck’s towers were remarkable in that they were all steel, and they were defended by Engineering News, which was “utterly opposed to false ornamentation in similar structures and to any attempt to disguise the real materials of construction or the chief lines of stress.” The journal did admit, however, that, “in a monumental work of this character, in the center of a great city, good taste in design and proper ornamentation must be considered; and if a more pleasing effect can be secured … the effort should certainly be made and is worth the added cost.”

  In his report to the commissioners in September 1896, Buck asserted that the bridge could be completed by January 1, 1900, at a cost of $7 million, which compared very favorably with the $15-million final price tag of the Brooklyn Bridge. With regard to the cost, Engineering News criticized the commissioners for being overly frugal with the salary of the chief engineer, upon whose “judgment, skill and experience the safety and convenience of the great numbers who will use the bridge for generations to come, depend solely.” Buck’s salary was $10,000 per year, whereas “the same commission pays out about $75,000 for two and one-half years’ work of a legal counsellor.” The editorial went on to anticipate what Lindenthal would say of Cooper a decade later—namely, that the low compensation granted engineers was a reflection of the “ignorance of the true value of the engineer” in such a large project, and it was “humiliating to the whole profession of engineers.” The question of the compensation of engineers versus lawyers was especially keen at the time, because an injunction had been sought against the commissioners, who had limited bidding to those who could supply steel made by the “acid open-hearth process,” as specified by Buck. The court refused to issue the injunction, and Engineering News praised the decision, concluding, “An engineer may not be infallible in his decision of engineering questions; but we shall make no gain by setting a lawyer to review his decision.” An engineer like Buck was receptive to criticism, however, and the lines of the deck were much improved in a revised view of the bridge published later in the year. Though it retained the straight-cable profile on the land-based spans, because they were to be supported from below as girders and not suspended from the cables, the deck had achieved a continuity that Buck’s earlier sketch had lacked. Whether the Williamsburg Bridge would be seen as a graceful swan or as an ugly duckling beside the Brooklyn Bridge would be largely a matter of taste.

  Sketch of an early design detail for a tower and the roadway of the Williamsburg Bridge (photo credit 4.13)

  Since a suspension bridge was required by the legislation authorizing the crossing, a cantilever could not be considered, even though it might have been more economical. However, economic considerations rather than aesthetic ones did strongly influence the appearance of the Williamsburg Bridge, especially with regard to its towers and cables, among the most costly components of any suspension bridge. Furthermore, economic and technical design factors are often intertwined. The decision, for example, to have the cables come straight down from the towers to the anchorages, and not support the land spans, meant shorter and lighter cables could be used, thus reducing their size and thereby their cost. Had stone or masonry towers been employed, they would have had to be very wide and heavy, in order to accommodate all the rails and roadways that would have had to pass through them. Employing lighter steel towers made smaller foundations (very costly components of any bridge) possible, and much time and cost were saved. “Roughly speaking, masonry towers would require foundations twice as large, would cost five times as much, and would take three times as long to build,” according to a contemporary report. Moreover, using steel towers meant they could be built taller, thus allowing the cables to have a deeper curve; they did not have to be stretched so tight, and so could be smaller in diameter. Economic considerations also led to the choice of steel viaducts rather than masonry arches for the bridge approaches.

  The construction of the Williamsburg Bridge was well under way when its administration was passed from a board of commissioners to the newly appointed commissioner of bridges, Gustav Lindenthal, on January 1, 1902, ending Buck’s role as chief engineer. Though Lindenthal must have had severe r
eservations about the design and appearance of the Williamsburg Bridge, he avoided talking about them in his brief official address at the dedication ceremonies, in which he announced that the bridge was ready for traffic, on December 19, 1903. He simply described the monstrosity he had inherited as “the heaviest suspension bridge in existence, and the largest bridge on this continent.” In comparing the Williamsburg to the Brooklyn Bridge, he noted that the newer structure was twice as strong—something New Yorkers would have appreciated, since the limitations on the strength of the Brooklyn Bridge had curtailed the commuter traffic across it for some time. Nevertheless, it was the older bridge that was the architectural success: “The imposing and stately stone towers of the Brooklyn bridge give that structure the appearance of great strength, but in the steel towers of the new bridge, and in all its other elements, a greater power of resistance is hidden.”

  The Williamsburg Bridge, upon its dedication in December 1903 (photo credit 4.14)

  Rather than dwell on comparisons, however, Lindenthal spoke of the future of bridges. His words were prescient:

  So far as engineering science can foretell with confidence, this colossal structure, if protected against corrosion, its only deadly enemy, will stand hundreds of years in unimpaired strength.…

  Our city will be pre-eminently the city of great bridges, representing emphatically for centuries to come the civilization of our age, the age of iron and steel. A time must come, not many generations distant, perhaps not more distant than the crusades in the past, when the building of such colossal structures will cease because the principal material of which they are molded, that is, iron and steel, will not be [any] longer obtainable in sufficient quantity and cheapness. When the iron age has gone, the great steel bridges of New York will be looked upon as even greater monuments than they are now.

  Gustav Lindenthal, as he appeared when he was commissioner of bridges for New York City, 1902–03 (photo credit 4.15)

  For all of Lindenthal’s grand projections into the future, the Williamsburg, along with many other New York bridges, would be in danger of collapsing long before the century was out. Forgetting his caveat about a bridge’s “only deadly enemy,” corrosion, New York and many other cities would during times of fiscal crisis neglect and defer maintenance of bridges like the Williamsburg to an alarming degree.

  Even when the Williamsburg was young, there were problems with it. Within three years of its completion, headlines reported that, because it had “such a liking for the Borough,” the bridge was “slipping to Brooklyn.” Evidently, the bridge had been “out of place since it was built,” but it was only then becoming known that “efforts to correct it had failed.” According to The New York Times, “a piece of engineering computation of the utmost nicety” was taking into account every ounce of material in the structure to determine the needed adjustment, so that the heavy cars of the elevated railroad could be allowed to run over it. Studying, straightening, and strengthening the Williamsburg Bridge continued on and off for about a decade. Two additional supports were added under each of the (unsuspended) land spans, and additional steel was added to the deck so that it could carry the heavier subway cars that had been developed since the bridge was designed. In fact, something similar was going to happen to many of the bridges around the world, because of changing conditions and philosophy, as articulated in 1911 by one of the engineers involved with the Williamsburg Bridge strengthening project:

  Mr. Buck designed the bridge on the theory that traffic should adapt itself to the bridge; we are now proceeding on the theory that such a bridge should adapt itself to traffic and that it should be as good as any other for traffic purposes, and not be a weak link. Mr. Buck designed the bridge for small locomotives drawing trailers. To-day, in a six-car train, there are generally four motors, all heavier than any of the old locomotives. The trolley cars also have increased in weight. The bridge is perfectly able to carry its traffic to-day, but as it now stands it would be inadequate for the future. Ten-car steel trains will probably be run through the subway loop, for one thing, and for such conditions we must provide.

  Buck had, however, designed a sound if unattractive bridge for the conditions he knew and under the conditions he worked. When some corrosion was discovered on the wrapping of the cables, they were uncovered in 1921 and found to be well preserved, and the steelwork generally to be in “perfect condition.” At that time, Engineering News-Record, which had in 1917 been formed of a merger of Engineering News with the Engineering Record, noted that this condition of the cables “gave fair assurance that main parts of the great New York suspension bridges have an indefinite length of life.” Indeed, the journal was tempted to say, they had an “unlimited life,” if properly cared for:

  Such bridges, in other words, are not subject to perceptible decay, and so far as corrosion is concerned they may remain free from measurable deterioration if intelligent inspection and maintenance are applied. As we look at the ancient stone bridges of Europe we reflect with wonder and admiration on their endurance through the ages; yet it is not beyond the bounds of possibility that our great steel bridges may survive as long.

  Intelligent inspection and maintenance are more readily called for than provided, however, as has been discovered in more recent years. Times and conditions change. Even the great stone monuments of Europe have been found to be susceptible to increasingly acidic environments. Inspection can uncover deterioration, but arresting or reversing it is another matter. Yet, in the early years of this century, when vehicle emissions were not even dreamed to pose the threat to stone and steel that we know them to today, bridges continued to be designed for the conditions of the time. And there were many bridges to design.

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  If the Williamsburg Bridge was well under way when Lindenthal became commissioner of bridges in 1902, two other East River crossings were not. Both the Blackwell’s Island Bridge, farther north, and the Manhattan Bridge, to be constructed between the Brooklyn and the Williamsburg, were still on the drawing board. (Though the foundation for the Brooklyn tower of the Manhattan Bridge had actually been contracted for, this in no way meant that changes could not be made in the design of the towers themselves or the general superstructure.)

  Shortly after a city ordinance authorizing a third bridge across the East River between Brooklyn and Manhattan was signed by the mayor early in 1900, bonds amounting to $1 million were issued, engineering work was begun, and bids for foundations were invited by early March. Since the Manhattan Bridge, as it was called from the beginning, was to be located wholly within the city of New York, the process was relatively efficient. The design had been largely completed when Lindenthal took over as bridge commissioner.

  Among Lindenthal’s early frustrations in the job were the delays accompanying the cable-making for the Williamsburg Bridge, which “dragged woefully” well into 1902. The cables were being spun by the John A. Roebling’s Sons Company, and Lindenthal “was very much annoyed at the delays shown by the Roeblings in executing their contract.” When the contract expired months before the cables were completed, Lindenthal deducted $1,000 a day from the payment to the company, which in the end amounted to a penalty of about $175,000. The Roebling firm, which had been excluded by New York politics from supplying the wire for John and Washington Roebling’s own bridge, took the city to court, claiming that the bridge commissioner had not furnished them the space needed for their operations, and they were awarded the money that had been withheld. Whether it was the frustration accompanying the delay or the poor relations with Roebling’s Sons, Lindenthal turned away from wire-cable suspension bridges and redesigned the Manhattan Bridge with eyebar chains, a system he had employed for the Seventh Street Bridge in Pittsburgh.

  The original plans for the Manhattan Bridge were made under the supervision of chief engineer R. S. Buck, who, though no relation to L. L. Buck, had worked as assistant to him in calculating stresses and as resident engineer on the Niagara arch-bridge project. Shortly af
ter the new bridge commissioner assumed office, R. S. Buck resigned, and Lindenthal assumed the engineering work on the East River structure. Commissioner Lindenthal’s first semiannual report announced that changes in the plans for the Manhattan Bridge were prompted by the delays on the Williamsburg Bridge, but he also gave the positive reason of economy of construction and maintenance, an argument that was by no means universally accepted by bridge engineers. The new plans, published in Engineering News early in 1903, showed a radically different suspension bridge, with towers that were not rigidly fixed at their base, and with the stiffened eyebar cables that Lindenthal preferred. As with his still-unrealized North River Bridge, this meant that the stiffening system was incorporated into the cables rather than being part of the deck structure. The Manhattan design was said to be so stiff it could be thought of as an inverted arch.

  Lindenthal’s design for the Manhattan Bridge, employing eyebar chains (photo credit 4.16)

  Though Lindenthal argued that the design had architectural as well as engineering merit, the mayor submitted it to a board of five engineers that he had appointed: Lieutenant Colonel Charles W. Raymond, the army engineer; bridge engineers George S. Morison, C. C. Schneider, and Henry W. Hodge, of whom more shall have to be said later; and Professor Mansfield Merriman, an 1871 graduate of the Sheffield Scientific School at Yale and head of the Civil Engineering Department at Lehigh University since 1881. All of the board members were members of the American Society of Civil Engineers, which added credence to the appointments. Theodore Cooper—whose Quebec cantilever approach span was just under construction, but who had little experience with suspension bridges—would replace Raymond before the board reported.