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

by Henry Petroski

  While Ellis would certainly appear to have been badly treated by Strauss, he also seems not to have been able to maintain a sound perspective on the matter at the time. Strauss eventually replaced him with Clifford E. Paine, a onetime student of Ellis’s at the University of Michigan and an associate of Strauss who once quit his employ “in protest over his boss’s interference with his work.” He was hired back with assurances that he would be left alone. Paine’s strong personality and central position on the Golden Gate project were subsequently demonstrated again in the fact that Strauss Engineering Corporation became Strauss & Paine, Inc., in 1935, about halfway through the Golden Gate construction. In a brochure available from the Bridge and Highway District, Paine is identified as “principal engineer during the design and construction” of the bridge. When it was completed and a plaque was to be prepared, Paine wanted to be identified as “Assistant Chief Engineer,” but Strauss preferred that the credit read “Assistant to the Chief Engineer.” Today, the plaque, on the southeastern face of the eastern leg of the San Francisco tower, identifies Paine as “Principal Assistant Engineer.” Others receiving credit are Russell G. Cone, as “Resident Engineer”; Charles Clarahan, Jr., and Dwight N. Wetherell as “Assistant Engineers,” and the consulting engineers Ammann, Derleth, and Moisseiff. There is no recognition whatsoever of Charles Ellis here, or in the listing of the engineering staff in Strauss’s final report to the board of directors.

  The Golden Gate Bridge opened on May 27, 1937, with an event known as Pedestrian Day. By 6 a.m., about eighteen thousand people had assembled on both sides of the bridge to be the first to walk over it. Over the course of the day, an estimated two hundred thousand strolled across the miraculous span. In 1987, as a means of commemorating the Golden Gate’s fiftieth anniversary, another Pedestrian Day was announced, but so many people showed up before the opening ceremonies that they pushed onto the bridge and pre-empted the usual political speeches. It was estimated that about a quarter-million people were crowded onto the Golden Gate at one time, thus testing it as it had never been before. The bridge, which has come to be known among engineers for its flexibility in the wind, for having been stiffened since construction, and for having been found structurally unsuitable to carry an extension of the Bay Area Rapid Transit system into Marin County, had the graceful arc of its center span flattened out under all the people in 1987, and there was some concern for its safety.

  The Golden Gate Bridge, in its dramatic setting (photo credit 5.16)

  It is unlikely that the centennial of the bridge will be celebrated with another uncontrolled Pedestrian Day, unless substantial structural retrofitting work is done in the meantime. This may indeed occur, for after the 1989 Loma Prieta Earthquake, extensive plans were prepared to make the bridge capable of surviving a quake registering as high as 8.3 on the Richter scale, to meet standards set by the state of California. The Bridge and Highway District’s $128-million project was first delayed by an environmental study required by the Federal Highway Administration, and then by disagreements over liability between the district and the engineering firm of Steinman, Boynton, Gronquist & Birdsall. This successor firm to David Steinman’s practice felt it was being asked to provide more security against financial loss than the district itself had felt prudent, and so refused to sign a contract for the retrofitting job. The irony of this development is only evident in the context of events subsequent to the completion of the Golden Gate Bridge, when Steinman and Ammann disagreed over the causes and cures of movements of their own suspension bridges in the wind. But that was still in the uncertain future when the Golden Gate Bridge was opened on Pedestrian Day, 1937.

  On that day, forty-five years after he had proposed a bridge connecting the continents of Asia and North America over the Bering Strait, the class poet Strauss commemorated the opening of the golden bridge that he had built across the Golden Gate with a new poem, which began:

  At last the mighty task is done;

  Resplendent in the western sun, …

  Though the poem did not involve Strauss directly, except as author, neither did it celebrate the assistant and other engineers who had labored over and checked calculations for the foundations, towers, and cables. The bridge itself is the hero of Strauss’s poem; it deals mythically with the setting and the structure, which is anthropomorphized in titanic proportions. The bridge was destined to be, “for Fate had meant it so,” and only in the fourth stanza did the poet begin to hint at the human toll such an engineering project could take:

  Launched ’midst a thousand hopes and fears,

  Damned by a thousand hostile sneers,

  Yet ne’er its course was stayed;

  But ask of those who met the foe,

  Who stood alone when faith was low,

  Ask them the price they paid.

  • • •

  An Honored cause and nobly fought,

  And that which they so bravely wrought,

  Now glorifies their deed;

  No selfish urge shall stain its life,

  Nor envy, greed, intrigue, nor strife,

  Nor false, ignoble creed.

  Strauss’s vision of the battle for the bridge appears to have been of one among the human emotions that dominate the political and financial design, rather than among the mathematical and material forces that must be reconciled to make the structure work. On the other hand, Ellis seems to have fought the fight entirely on the technical level, and he certainly must be considered one who paid a price. He may never have read Strauss’s poem, and it might not have mattered to him if he had. It is known that Ellis, who lived until 1949, never visited the bridge; that may be a fair indication that his satisfaction lay in the designing rather than the building—or that he was nursing a mighty grudge.

  Later in his own career, David Steinman would take up writing poetry, adding to his list of accomplishments and awards, and he too would versify on his own poems in steel. However, for every Strauss and Steinman, who seemed to wear their accomplishments as Waddell wore his medals, there have always been and no doubt always will be uncounted and unheralded engineers like Ellis designing and building bridges equally worthy of poetry. Many such engineers were glad to have jobs in a worsening economic climate; few were as contentious and uncompromising as Ellis with their chief engineers.

  10

  The sense among bridge engineers generally in the 1930s was one of supreme confidence in their theoretical capabilities, which Ammann himself articulated in an article in Civil Engineering in 1933: “When Telford planned the Menai Bridge [in the 1820s] he developed the major forces largely on models. Bridge failures of that day resulting from inadequate design might be excused on the ground of insufficient knowledge; today the designer has no such alibi.” Ironically, Telford’s bridges might themselves have served as models of the kinds of failure that could still befall bridges, and the designer, whether modern or not, indeed had no alibi for being unaware of such things. But designers in the 1930s certainly seem to have been oblivious to the power of the wind, as developments soon would show.

  In 1930, Ammann rose from bridge engineer to chief engineer of the Port Authority, and as such he oversaw the planning and construction of the Lincoln Tunnel, which entered Manhattan at 39th Street and thus provided, when it opened in 1937, the long-dreamed-of midtown crossing of the Hudson. That same year, Ammann assumed simultaneously the position of director of engineering of the Port Authority. With the growing use of automobiles, other New York City transportation needs had been developing between the boroughs, but those intracity projects were under the control of the master planner Robert Moses, who was chairman of the Triborough Bridge Authority. This autonomous and yet highly political entity was named after its first large project, which was to connect the three boroughs of Manhattan, Queens, and the Bronx with a system of bridges and viaducts known collectively as the Triborough Bridge, whose centerpiece was a suspension bridge across the Hell Gate just south of and parallel to Lindenthal’s famous
railroad arch. With his success at the Port Authority well established, Ammann was asked by Moses to bring his (and Allston Dana’s) experience to the troubled Triborough Bridge project, whose Tammany engineers prized granite towers over traffic lanes. Since considerable design work had already been done, the bridge and its squat towers could not be completely reshaped to look like an Ammann structure. Nevertheless, the bridge, completed in 1936, remains a major achievement in facilitating traffic movement within the city.

  From 1934 to 1939, while continuing in his position with the Port Authority, Ammann served also as chief engineer of the Triborough Bridge Authority. One of the projects that Moses promoted toward the end of this period was a bridge between Brooklyn and the part of lower Manhattan known as the Battery, with a central anchorage near Governors Island. The proposed design consisted of two suspension bridges in tandem, not unlike the San Francisco-Oakland Bay Bridge, then recently completed on the West Coast; Moses’s bridge was so convincingly drawn on an aerial photograph of New York Bay that one would swear that the bridge was a reality. A tunnel at the location had been proposed at least a decade earlier, and the New York City Tunnel Authority had been created to construct it. Moses was not interested in giving up any opportunity to control another great project, however, and while the Tunnel Authority was looking for financing during the Depression, the bridge alternative was proposed. Considerable opposition arose to an above-water crossing, not only by the War Department but also from citizens who did not want to see the spectacular and world-famous view of the lower-Manhattan skyline hedged by the enormous elevated approach roads that would have had to accompany a bridge.

  The tunnel project, under the direction of chief engineer Ole Singstad, had been estimated to cost about $65 million, but Moses, who had earlier made a deal with Mayor Fiorello La Guardia that a federal loan covering part of the cost would be supplemented by funds from the revenue-rich Triborough Bridge Authority to help construct the tunnel and connecting highways, put the cost at $85 million. This inflated figure gave Moses an excuse to renege on his agreement with the mayor, arguing that the bridge could be built for about half the cost of a tunnel. However, Moses’s figure for the bridge did not square with the cost of other spans then under construction, and Ammann, the designer of the structure, was asked for his opinion on the matter. The engineer was apparently caught off guard, and, torn between his engineering integrity and his loyalty to Moses, who had given him opportunities to continue to design and build great spans, Ammann hemmed and hawed enough to lead representatives of a citizens’ group to ferret out the true costs of each complete project; this comparison favored the tunnel.

  A controversial bridge designed in the mid-1930s, and strongly advocated by Robert Moses fifteen years later, convincingly drawn onto a photograph of its dramatic proposed location between Brooklyn and the Battery, in lower Manhattan (photo credit 5.17)

  The Brooklyn-Battery bridge thus became a footnote to Ammann’s portfolio of designs and dreams, usually not even mentioned by biographers. Though the general slowdown in large projects toward the end of the 1930s must certainly have played a role, the uncomfortable incident relating to lower Manhattan must also have influenced, if not triggered, his departure from civil service, and he went into private practice the year the bridge-tunnel controversy came to a head, 1939. However, before he left the employ of Moses, Ammann did, as chief engineer of the Triborough Bridge Authority, oversee the design from scratch and the realization of a major suspension bridge between the Whitestone section of Queens and the Bronx. Planning for that bridge had begun in 1935, and the Bronx-Whitestone Bridge was to be completed in time to serve the traffic influx expected for the 1939 New York World’s Fair. Since the site for the bridge did not constrain the lengths of the main or side spans as the Palisades location did those of the George Washington Bridge, Ammann had free rein to design a structure whose proportions were chosen principally for economic and aesthetic reasons. The latter was extremely important in the case of the Bronx-Whitestone, for its entire profile, including anchorages and approach spans, was to be in clear view, “so that the structure as a whole [would] be visible to an extent that [was] true in no other case.” No conflict between architectural and structural considerations was necessary here; in a report published in Civil Engineering to coincide with the completion of the bridge in April 1939, Ammann wrote of how modern engineers like himself could view such matters when unencumbered by the constraints of the past:

  It is now well established that long-span suspension bridges for modern highway traffic may have a relatively flexible stiffening system, and that the degree of flexibility has a material effect upon the economy of the design. In this respect the Bronx-Whitestone Bridge marks another radical departure from past theories and practice. Its stiffening girders have greater flexibility in relation to span length than any other suspension bridge built in recent years, except the George Washington Bridge in its present state with only a single unstiffened highway deck. The latter bridge, however, with a present roadway capacity equivalent to that of the Bronx-Whitestone Bridge, has a suspended dead weight per linear foot 2½ times greater, a center span 56 per cent longer, and side spans somewhat shorter, all of which factors contribute to the greater rigidity of the unstiffened cables.

  It was the aim of the writer, on esthetic as well as structural and economic grounds, to restrict the height of the floor structure to a minimum, to avoid trusses, and to keep the top at such an elevation above the floor as not to obstruct the view of the landscape from passing vehicles. A depth of 11 ft for the stiffening girders was found to be sufficient and to fit best into the floor structure. This is only 1/210 the length of the center span and only 1/70 of the side span.

  Ammann here laid down the prevalent philosophy of suspension-bridge building in the later 1930s. The solid plate girders defining the deck profile and the “design of the towers as rigid frames without any diagonal cross bracing” contributed to “the graceful appearance and structural simplicity of this type of bridge,” according to Ammann. Even the anchorages and approach viaducts were “reduced to a minimum as to materials required for strength and stability,” and were “devoid of extraneous architectural embellishments.” Furthermore, all these factors “in no small degree contributed to the unprecedented speed in the construction of the bridge.” Ammann’s apparent about-face with regard to “architectural embellishments” was more a turning from the traditional view that masonry provided the texture of choice for monumental works to the modernist view, pre-eminently expressed by Le Corbusier, which saw beauty in steel. The outline of the towers of the Bronx-Whitestone were in fact not unlike those of the early sketches for the George Washington, when Ammann had worked with the architect Ruegg. After the unrealized Cass Gilbert treatments of that bridge, Ammann must have been happy to be collaborating on the Bronx-Whitestone with yet another architect, Aymar Embury II.

  Embury had already established himself as an architect to the elite, having designed a classic dormitory at Princeton University and a good number of estates on Long Island, when Robert Moses persuaded him to work on parks in New York. In a remarkable series of articles in Civil Engineering in early 1938, Embury seemed to be single-handedly trying to heal the rifts that had developed between architects and engineers. He acknowledged help from the likes of Ammann, Steinman, Waddell, and, “in particular,” Allston Dana, who was engineer of design on the Bronx-Whitestone as he had been on the George Washington. Indeed, Embury wrote that he “had the good fortune to work in close association with” Dana. Embury went on to say that he and Dana “had a fairly free hand, although, of course, the designs were always subject to Mr. Ammann’s criticism and never out of his control. We were, in a sense, his instruments, and were guided by his desires as to the lines along which we should proceed.”

  The Bronx-Whitestone Bridge as completed in 1939, with an anchorage in the foreground (photo credit 5.18)

  Embury came to Ammann’s aid late, however, and
it was only on the design of the Bronx-Whitestone anchorages that he worked with Dana de novo. They “wanted the anchorages to look like an anchorage and like nothing else,” Embury reported, in keeping with Ammann’s desire that “the whole bridge should be kept smooth, sharp, and clean.” The design for the anchorages was “made without reference to any precedent,” and the final result was one of simplicity and appropriateness for the foundation conditions. In his paper on the aesthetics of bridge anchorages, Embury also showed alternative designs for the anchorages of the Triborough Bridge and proposed designs for the anchorages of the George Washington Bridge. Then, five years after the opening of that great bridge, the completion of the architectural treatment of its New York anchorage was still on hold “until traffic conditions should necessitate construction of the lower deck.” In the meantime, Cass Gilbert had died, and his design was being criticized as “an anachronism in a modern steel bridge.”

  But Embury did not have only positive things to say about engineers in his articles, for he spoke of “design by drawing instruments,” and wondered “how often do engineers, because their triangles are 45, 30, and 60 deg, use one of these slopes for diagonal members?” Architects also came in for criticism for following “the easiest way,” and Embury called for more of a meeting of the minds: “Engineers should be good architects, and architects good engineers!” He very graciously closed the second in his series of articles with a note on his collaboration, in which “a reversal of function” surprised those involved in the project: “As a rule it has been the architect who has suggested and the engineer who has acted as the artistic critic.” Yet modern steel suspension bridges still presented immensely difficult problems in both structural and architectural design, not least of which was the problem of massive steel superstructures in close proximity to massive masonry anchorages. And solutions to such problems were often ineffable. In the end, Embury admitted that, although engineer and architect had in their anchorage design “a shape that pleases us both, we do not know why.”