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

by Henry Petroski

  Lindenthal, whose own career was then in its twilight, was to be swayed neither by a portrait nor by the myth of Waddell the prolific author, who in a biographical sketch that may very well have been autobiographical was said to write out “in longhand his accurate and well-finished papers and discussions in his office or during numerous long railroad trips back and forth across the continent.” No matter how dedicated to his writing Waddell might have been, Lindenthal expected it to stand up to engineering scrutiny. His basic technical criticism of the 1916 book was nicely summarized in the lengthy review:

  J. A. L. Waddell, from the frontispiece of Memoirs and Addresses (photo credit 4.31)

  The book … appears to be valuable and authoritative only in so far as it deals with the engineering of bridges of ordinary span and type, that have already become more or less standardized. When the author ventures outside of this field into the domain of long-span and indeterminate structures, his insufficiency of knowledge and experience are betrayed [on the specific pages cited], and his lack of grasp of the big questions in this field becomes evident. This may sound like harsh criticism, but it appears to be justified in view of some of the author’s pretentious but erroneous judgments on higher-class structures.

  Lindenthal takes Waddell’s discussions of several topics as an opportunity to set the record straight, as on the characteristics of cantilever bridges, on the safety of suspension bridges, and on aesthetics. On Waddell’s “witticisms” about the Queensboro Bridge, for example, Lindenthal remarks that “there are few structures, even of those designed by the author, about which some amusing things could not be written, but such do not furnish instruction to engineers,” and he goes on to discuss the political system in which “engineers are as often abettors as victims.” With regard to aesthetics, Lindenthal wonders if Waddell’s “taste will always be shared by other designers.” When he elaborates, Lindenthal appears again to have something of his own experience on his mind:

  The author’s repeated reference to aesthetic appearances based on nothing more than curves in the top or bottom chords will appear to others as rather naïve. This chapter on architecture is well meant as an earnest plea to bridge engineers to show themselves in their work as cultured men. The author, however, in undertaking to furnish instruction and guidance to seekers of the aesthetic in bridge construction, has set himself a task that is evidently beyond his scope. For any bridge structure requiring architectural consideration the bridge engineer will do well to consult a competent architect; and experience has shown that not every architect is competent here.

  10

  The question of bridge aesthetics and the role of the engineer versus the architect in bridge design was one that was to grow well beyond a difference in point of view between Waddell and Lindenthal, and some of Lindenthal’s views may inadvertently have threatened the position of engineers generally. In 1919, a Delaware River Bridge Joint Commission was created by the legislatures of Pennsylvania and New Jersey, and among its first orders of business was the appointment of a board of engineers to study specific sites and types of bridges. In the meantime, the Pennsylvania State Art Commission wrote to the governor calling for an architect to be put in charge, stating that the commission members were “convinced that the question of ‘where’ and ‘what’ are of greater importance, and more difficult to answer, than ‘how’ to build it.” Indeed, to their mind, the “how” was “after all but a detail.” The insinuations and arrogance of the art commissioners would have been enough to incite the engineering community, but the final straw was contained in a statement that made patently false claims about the history of bridge building in America: “The great bridges of New York have all been planned by architects, though, of course, built by engineers. They are beautiful because they fulfill their purpose, and are fittingly designed, with due consideration to the ‘where’ rather than only the ‘how’ ” Perhaps Bridge Commissioner Lindenthal had retained architect Hornbostel, and perhaps engineer Lindenthal’s ego had driven him to demand the title of architect as well as engineer on the Hell Gate project, but it was a gross misstatement to say that architects had decided where and what bridges were built across the East River. Indeed, as the stories of the bridges reveal, they were conceived, located, relocated, and designed by the (sometimes conflicting) recommendations of engineers, and there were long and continuing disagreements as to whether any of the bridges was even beautiful or fulfilled its purpose.

  Suspension- and cantilever-type bridge designs proposed to cross the Delaware River between Philadelphia and Camden, New Jersey (photo credit 4.32)

  Various engineering groups responded with “resolutions of remonstrance,” demonstrating their own firm grasp of the history of the New York bridges. Philadelphia’s Society of Municipal Engineers pointed out that “engineers are as keenly aware as any class of citizens, of the need for taste and beauty in structures erected in public view,” and they pointed out a difference between the conditions under which engineers and architects sometimes work. In designing a bridge or some other structure, the engineer is often directed by the client to provide the most economical, no-frills structure. The architect, on the other hand, is “oftenest called in by clients who wish to pay the necessary price for taste and beauty,” and so does not work under the handicap of strict economy in design. The engineer-architect issue was a threatening one, but it became moot, at least in Philadelphia, when Ralph Modjeski was chosen as chief of the board of engineers charged with making recommendations as to site and type of bridge.

  After the location of a suspension-bridge design was settled upon and approved, construction on the Delaware River Bridge was begun early in 1922. The final decision was probably made more expeditiously than it might have had there not been a strong desire to have the bridge ready for the Sesquicentennial of the Declaration of Independence, on July 4, 1926, and an experienced engineer was most likely to be able to do that. Among the critics of the design was Lindenthal, perhaps remembering Modjeski unkindly as the engineer who gave the stamp of approval to the Manhattan Bridge, whose final plans had, of course, been altered and modified from Lindenthal’s own changed design. Thus he wrote that “the engineer who thinks merely of stresses must combine with the architect, who deals with artistic forms.” In focusing on the towers, the “most prominent feature” of suspension bridges, he asserted that “from the aesthetic point of view, metal towers, no matter how finely designed, will never equal stone towers.” At this time, as we shall see, his own design for the North River Bridge was evolving toward stone from its original steel towers, whose curve had resembled the Eiffel Tower. That was the structure that he still considered “the finest example of an artistic metal tower,” even though “as an architectural creation it does not impress the beholder with that feeling of dignity and majesty which he experiences at the sight of any of the great spires in famous cathedrals.” The Williamsburg Bridge towers, for which “no architect was consulted,” were “bandy-legged,” and the Delaware River Bridge towers were “too much on the utilitarian principle of braced telegraph poles or derricks, holding up ropes.” However, Lindenthal also knew as an engineer that metal towers were “lighter and cheaper,” thus requiring not only less costly and time-consuming foundations but also less capital investment. In a situation where a bridge is desired to be ready for a sesquicentennial, for example, such considerations are naturally persuasive, though seldom sufficiently so to all. In this case, one of the most effective critics was an artist.

  Perspective drawing of Delaware River Bridge (photo credit 4.33)

  Joseph Pennell, who was born in Philadelphia in 1857, attended evening classes at the Philadelphia School of Industrial Art and then the Pennsylvania Academy of the Fine Arts on and off around 1880, his talents as an illustrator blossoming. He then worked mostly in Europe, traveling back to the United States to record American engineering projects, from which developed the “Wonder of Work” theme of his sketches of projects under construction, such a
s the Panama Canal and Hell Gate Bridge. World War I caused him to return to the United States more or less permanently, and in 1924 he sketched the Delaware River Bridge under construction. The title of his etching, The Ugliest Bridge in the World, was unkind to the incomplete structure, which was not yet a fully formed bridge. However, the relatively wide towers, necessarily so to accommodate the eight lanes of traffic, were rather squat-looking for their height. It is one of these towers, which Lindenthal found wanting in their design, that is the focus of Pennell’s drawing.

  Like the story of great bridges generally, the history of the Delaware River Bridge was long and tortuous. Plans were proposed to cross the river between Philadelphia and Camden, New Jersey, as early as 1818. In 1843, a model suspension bridge was exhibited at the Franklin Institute Fair, and in 1851 a suspension bridge with four-thousand-foot spans was proposed by John C. Trautwine, Sr., but neither attracted much serious interest. New Jersey and Pennsylvania bridge commissions were in place in 1918, when the firm of Waddell & Son was retained to make a consulting-engineering study. The report concluded that a bridge would be preferable to a tunnel and presented a suspension design with helical incline approaches, no doubt prompted by the high cost of land for the conventional means. The same approach scheme had also been employed in a Waddell design for a bridge across the entrance to the harbor at Havana, Cuba, and had been used as an illustration in the chapter on aesthetics in Bridge Engineering. A consulting architect, Warren P. Laird, was subsequently engaged to advise on the Delaware River Bridge’s location, and the brouhaha over whether engineers or architects should take the lead in such projects resulted.

  Comparison of steel-tower designs of several contemporary suspension bridges (photo credit 4.34)

  A photograph of the Delaware River Bridge under construction, and Joseph Pennell’s etching of “The Ugliest Bridge in the World.” (photo credit 4.35)

  A Delaware River Bridge Joint Commission, created by the two states in 1919, the following year appointed the board of engineers with Ralph Modjeski as chairman and with the distinguished Philadelphia engineers George S. Webster and Lawrence A. Ball as the other members. Suspension and cantilever designs were considered, the former winning out on economic grounds. Modjeski effectively became chief engineer of the project, and he selected Leon Moisseiff engineer of design and Clement E. Chase as principal assistant engineer. Paul P. Cret served as architect to the project, but under the engineer Modjeski, whose personality and predilection for the dramatic dominated throughout construction. Physical construction began with a ceremony early in 1922, but, “in lieu of the traditional digging of the first spadeful of earth, a plank was torn loose” from a pier that the bridge would replace.

  Before the bridge was finished, a seemingly unresolvable difference of opinion arose between the states of New Jersey and Pennsylvania as to whether or not tolls would be charged. The New Jersey commissioners voted to halt the awarding of contracts—including one to wrap the cables before they began to rust—until it was agreed that tolls would provide funds for interest on and amortization of the bonds that were issued for construction. Philadelphia residents, on the other side of the river and the issue, preferred a free bridge paid for by taxes. Engineering News-Record reminded its readers that, “under the pressure of post-war costs and overdue public needs,” taxation had “largely ceased to be an attractive means of financing large public improvements.” After the Supreme Court granted Pennsylvania permission to sue New Jersey over the issue, the journal observed that, “if the outcome of Pennsylvania’s attempt to outwit the New Jersey taxpayer succeeds, future public toll-bridge proposals will not have an easy time of it.” In the end, it appears to have been public sentiment in Pennsylvania in favor of a toll that swayed that state’s legislators to retreat from their position. Construction resumed, and the bridge was officially opened to traffic on July 4, 1926. Engineering News-Record reported then that “it probably ranks as the largest public toll enterprise ever carried out,” but that distinction would not hold for long, although the bridge itself was expected by some to last indefinitely. At the twenty-fifty-anniversary ceremonies, for example, it was written: “There will be many more anniversaries, for no man can place a limit upon the time this bridge, magnificently designed, honestly constructed and scrupulously maintained, shall endure as the link between the states.” Such conditions of maintenance can continue practically, however, only as long as toll revenue or some other source of funds provides the resources.

  Sketch of Charles Evan Fowler’s proposal for suspension bridges of 3,500-to-4,000-foot main span to cross the Hudson River at three locations (59th Street, 83rd Street, and 178th Street) for a total cost of about $100 million, essentially the same design he proposed for a bridge between Detroit and Windsor, Canada (photo credit 4.36)

  By the mid-1920s, great suspension bridges were under construction or being considered in large cities across America, including at Detroit. The Ambassador Bridge, completed only three years after the Delaware River Bridge, would best its 1,750-foot main span by one hundred feet and thus hold the world’s record for a short while. But the record was to be almost doubled in New York in 1931, and increased by another 20 percent in San Francisco in 1937. Though Lindenthal may have conceived and submitted designs for some of these projects, it was the bridge across New York’s Hudson River that he really wanted to build, and for which he still held out hope. His latest design had steel towers enclosed in masonry, following the aesthetic he had recently espoused, and the 825-foot-tall, thirty-five-thousand-ton towers would be higher and more massive than the Woolworth Building, designed by the architect Cass Gilbert and opened in 1913. However, Lindenthal seems not to have completely lost his affection for the bare metal towers of his early North River Bridge design; it, and not its masonry-clad descendant, was illustrated in a long reflective article entitled “Bridge Engineering,” prepared by Lindenthal for the fiftieth-anniversary number of Engineering News-Record, in 1924.

  Lindenthal’s 1921 design for a Hudson River bridge at 57th Street (photo credit 4.37)

  11

  Approaching his seventy-fifth birthday, Lindenthal was both pragmatic and philosophical. Regarding financial constraints, on which he had a considerable opinion, he wrote: “Engineers are sometimes under the authority of laymen with whom financial considerations may seem more important than safety. If the pressure for cheapness comes from them, then the engineer should decline responsibility for the work.” After looking back over the previous half-century of railroad-bridge building, he began to shift into prognostication: “Large bridges costing millions of dollars were comparatively few and will probably become less frequent in the next fifty years.” He did not want to leave the wrong impression, however, for he continued to point out that the “size of bridges never was limited by question of what we could fabricate, but rather by financial considerations.” Perhaps Lindenthal was beginning to resign himself to the fact that his greatest dream would never be realized, but, then again, he knew that it was not because of the limitations of engineers or engineering.

  An illustration of Lindenthal’s proposed bridge, demonstrating how long and heavy its main span would be (photo credit 4.38)

  A 1921 comparison of a tower of Lindenthal’s bridge with the Woolworth Building, then the tallest skyscraper in the world (photo credit 4.39)

  Looking further into the future, Lindenthal thought it “probable that the zenith of large bridge construction” would be reached in the late twentieth or early twenty-first century, because of the “increasing cost of iron and coal” to make steel. He thought the “iron beds would become exhausted long before the coal mines,” and “the production and use of portland cement (which requires coal for calcination) will also cease,” and that stone bridges would “again be the only practicable lasting kind.” He continued, in a rambling historical mode:

  Bridge construction and bridge architecture will be to posterity in a certain sense a surer index of the progress o
f our present day civilization than houses, temples or cathedrals appear to us of past ages. This will be so because the economizing of iron, when it becomes costly, will probably begin in bridge and structural construction before it begins in other kinds of construction. The large sources of energy in nature, coal, water power, wind, tides, heat of the sun, etc., can none of them be utilized without large masses of iron for the tools, machinery and power plants necessary for the conversion of these energies into power for the use of man—all of them more necessary than iron bridges, which may be then structures de luxe. Surely they would have appeared as such to the armored knights only one thousand years ago, when an iron armor was worth nearly half its weight in silver. Iron bridges, iron ships and railroads will then be curiosities. The colossal consumption of iron will have come to an end. In a span of time much shorter than that from Tut-ankh-amen to the present, steel bridges will probably have disappeared from the face of the earth through corrosion and neglect. Iron is a more perishable material, particularly in northern climates, than stone of which were built the Pyramids and the Greek temples and the wonderful Roman arch aqueducts—all in frostless, benign climates. These could be built again, but not iron bridges.

  Lindenthal underestimated the world’s store of iron and did not foresee in 1924 the enormous amount of steel that the automobile would consume, nor did he seem to foresee the tremendous amount of pollution it and the steel mills in its service would create. Such developments would invalidate his climatic argument and threaten the Pyramids as much as iron bridges. But, in spite of his flight of iron fancy, the old man was still not willing to give up his dream completely; his last paragraph held out a glimmer of hope in civilization’s retreat from the iron age: