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

by Henry Petroski

  Holton Robinson, when he was engineer in charge of construction of the Williamsburg Bridge (photo credit 6.4)

  Robinson left the employ of the city in 1907 to join the Glyndon Contracting Company, fabricator of the cables for the Manhattan Bridge. Besides designing the machinery to effect the spinning of the twenty-one-inch cables, then the largest ever, during his tenure with Glyndon he produced an unsuccessful design for a suspension bridge to cross the St. Lawrence River at Quebec, where the great cantilever had failed. He left Glyndon in 1910 to build, as an independent contractor, a suspension bridge near his hometown; this structure was completed in about six months at a cost of $40,000, 50 percent lower than the lowest bid that had been received by the town of Massena. Over the next several years, Robinson worked on a variety of bridge, tunnel, and navy war projects; his experience was broad and deep by the time Steinman met the “modest, distinguished-looking man” in 1920.

  In 1922, Robinson was appointed consulting engineer for cable construction on the Delaware River Bridge between Philadelphia and Camden, New Jersey. He assured the joint commission that, instead of four smaller ones, two cables of thirty-inch diameter could be spun, thus simplifying construction, and he supervised their design before resigning as consulting engineer to work for the contractor, the Keystone State Construction Company, which was to make the cables. The office of Robinson & Steinman, in turn, was given responsibility for designing the temporary work and machinery needed to accomplish the task. In 1926, at a joint meeting of the Franklin Institute and the Philadelphia section of the American Society of Civil Engineers, Robinson, then in his early sixties, presented his first technical paper, “Construction of the Cables of the Delaware River Bridge.” For all his accomplishments, his boyhood shyness had not left him; “he suffered excruciatingly from stage fright and the experience so unnerved him that he vowed he would never repeat it.”

  He may have eschewed public speaking, but Robinson did not shy away from the physical challenges bridge engineers had constantly to face. According to Steinman,

  Even in his last years, Mr. Robinson was active, agile, and fearless in his outdoor work on bridges. He would climb on high steelwork or walk the cables of a suspension bridge with greater ease than most younger engineers. In 1941, during the investigations that followed the Tacoma Narrows … disaster, he was retained by the insurance companies, and made a personal examination of the cables of the wrecked structure. Although seventy-eight years old at the time, he calmly walked out over the 17½-in. cables, each 5,900 ft long and 450 ft high at each tower, to examine the condition of the wires and to cut out samples of the wire at midspan. His feat was rendered more difficult and hazardous by the fact that the hand ropes in the main span had been wrecked.

  Thus, in spite of his social reticence, Robinson suffered no fear in the face of technical or physical challenges. Steinman, on the other hand, was, ostensibly at least, as comfortable before large audiences as he was on tall bridges. The partnership of Robinson & Steinman, extremely complementary and compatible, would last for a quarter-century without a written contract between the men.

  The project that brought them together, the Florianópolis Bridge, was a success, thanks in large part to an unusual and distinguishing structural design by Steinman that had the eyebar chains doubling as the curved upper chord of the stiffening trusses, which resulted in a very economical structure. When it was completed in 1926, the Florianópolis Bridge, with a main span of over eleven hundred feet, was the largest in South America, and the largest eyebar suspension bridge in the world. Steinman’s article on the design of the bridge appeared in Engineering News-Record late in 1924, and he explained how the bridge was originally “designed along conventional lines,” which meant a wire-cable structure that looked very much like the Williamsburg Bridge, with which Robinson was so familiar. When a decision based on economy was made to use eyebars rather than cables, however, this led to a reconsideration of the truss, into which the eyebars then became incorporated. According to Steinman, first sketches showed a “most pleasing outline” for the truss, which curved as it did at the towers, but straight chords were employed in the final design, “in deference to the preference expressed by our client.” Such compromises might not be made by an engineer like Lindenthal, but Robinson and Steinman were more interested in establishing their firm’s reputation for economical and reliable work than in making an engineering or artistic statement.

  The Florianópolis Bridge, as originally designed by Robinson & Steinman, and as altered to suit the client (photo credit 6.5)

  The new truss-eyebar arrangement produced a very stiff bridge with less material, and such an economical solution was something which other suspension bridge engineers would now have to take into account. It presented a realistic alternative to the stiffened cables or stiffened eyebars, such as the kind Lindenthal had proposed for his North River Bridge, which were not integrated with a deck truss. An immediate response to Steinman’s article came in the form of a letter to the editor from Leon Moisseiff, who took exception to Steinman’s claim that his structure was the first to incorporate a bridge’s chain or cable into a stiffening truss that continued for the entire length of the main span. Moisseiff included a drawing of his 1907 design for a bridge over the Kill von Kull, which, “for better appearance,” continued the line of the truss through the towers. But a drawing is not a bridge.

  Moisseiff was, in a sense, echoing Ammann’s review, two years earlier, of Steinman’s book, A Practical Treatise on Suspension Bridges: Their Design, Construction and Erection. Since Ammann had written little for publication on suspension bridges up to that time, Lindenthal would actually have been the much more logical reviewer for Engineering News-Record to have chosen, and it seems very possible that he may indeed have passed the book on to his assistant chief engineer at the North River Bridge Company, as Ammann’s affiliation was identified over the review. The review itself might best be described as mixed, with Ammann finding parts done with “fair completeness” and thus providing a “useful manual, especially for the student or young engineer,” but also criticizing the book for not discussing matters of aesthetics. According to Ammann, Steinman also discriminated “against the eyebar chain” on technical grounds, but he was in fact ever flexible in his thinking, as the Florianópolis Bridge was to demonstrate.

  Steinman, both with Robinson and independently, began to get more and more significant commissions, and the younger partner wrote about them with facility. The Carquinez Strait Bridge, located about twenty-five miles northeast of San Francisco, was one such project. Consisting of two main spans of eleven hundred feet, it became the second-largest cantilever in the United States and the fourth-largest in the world when it was completed in 1927. The chief engineer of the bridge project was Charles Derleth, Jr., with William H. Burr as consulting engineer and Steinman as design engineer.

  But Steinman’s real ambition was to build world-class suspension bridges that would also be recognized as things of beauty. Though the Florianópolis Bridge was a major structure, its oddness of type and compromised lines, not to mention its location, put it in a category almost by itself. A new opportunity arose, albeit still off the beaten track, with the Mount Hope Bridge, which Steinman designed, and whose construction the firm of Robinson & Steinman supervised “to take the Island out of Rhode Island.” The total length of this bridge was over a mile, and its twelve-hundred-foot main span put it almost in a class with the major suspension bridges of the day. Its cross-braced towers suggested a Gothic arch above the roadway, and the bracing was topped by a crown of smaller crosses, this latter feature echoing somewhat the tower tops of several contemporary suspension bridges, including Modjeski’s Delaware River Bridge, whose towers Pennell so disliked. Steinman’s Mount Hope towers have a balanced look, however, and are in good proportion to the uniformly deep truss of the roadway. The bridge received the 1929 Award of the American Institute of Steel Construction as the most artistic new long-span brid
ge in America.

  At the same time, the firm of Robinson & Steinman was designing the St. Johns Bridge over the Willamette River at Portland, Oregon. With a twelve-hundred-foot main span supported from rope-strand cables, which for such a distance were found to be somewhat more economical than parallel-wire cables spun in place, this bridge was then the longest suspension type west of Detroit. According to Steinman, perhaps responding to Ammann’s criticism, “the desire to secure a beautiful public structure was a governing consideration” in the design, and the towers were the result of “extensive architectural studies,” although he identified no particular architect or style. The unique towers have battered (i.e., slightly inclined) sides, spires, and, in a more extreme fashion than the Mount Hope Bridge, Gothic arches above and below the roadway. The stiffening truss, however, is undistinguished, and there does not seem to be a successful integration of towers and deck. Although the bridge was described in the Robinson & Steinman firm’s brochure, Bridges Lasting and Beautiful, as “a poem stretched across the river” and “a symphony in stone and steel,” the aesthetic success of the towers and the overall bridge can be debated. The towers were designed to echo and harmonize with the dramatic scenery of evergreens, mountains, and clouds, visible through the four-hundred-foot-tall structures, but they seem too unintegrated into the natural setting. In something of a departure from tradition, the bridge was painted a pale green. In 1931, “on a gusty, rainy day,” Robinson and Steinman, whose firm had complete charge of design and construction, gave the newly completed crossing its final inspection from the open cockpit of a stunt plane which Tex Rankin, “northwest flying ace,” flew around the towers and over and under the roadway. Both engineers were thrilled by the experience, and with the bridge.

  In his memoir of Robinson, who died in 1945, Steinman described him as being “professionally connected with the construction of almost every notable suspension bridge built during his lifetime,” a fact that “was his chief pride.” Without detracting from Steinman’s eulogy of Robinson, this could be said of a number of the great bridge engineers; indeed, it almost naturally followed, because great engineers wanted to be associated with great bridges, whose designs in turn relied on a variety of engineers who had a variety of experience with the unique and specialized design and construction problems that were faced. Sometimes, of course, as in the case of the Tacoma Narrows Bridge, the greatness of the engineers has come to seem more important than the design itself.

  In any event, who would consult on what bridge had a lot to do with who was the chief engineer, of course, and who had the dominant reputation or the most correct politics at the time. When plans for the George Washington Bridge were being finalized in the mid-1920s, for example, Lindenthal, because of his relationship with Ammann, was a problematic choice as a consulting engineer. On the one hand, he was the engineer who had been most visibly associated with such a Hudson River project; on the other, his inflexibility and prior relationship to Ammann put him in a special category. Robinson, because of his extensive experience, was a natural choice, but his then recent association with Steinman may have presented problems for Ammann. As for Steinman himself, for all his writing about bridges, he was only just beginning to gain his first experience with their design and construction. In some accounts, however, Robinson and Steinman, in particular, “helped to design” the bridge, as consultants on the erection of the steel superstructure, even though they are not listed among the consulting engineers in the dedication program.

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  The 1930s were a heyday of large-bridge construction, with the George Washington opening in 1931 and the two great bridges connecting San Francisco with Marin County and with Oakland under construction simultaneously. Of these, the bridge to Oakland was actually completed first, in 1936, but it was to be permanently overshadowed by the Golden Gate, completed six months later, in 1937, with its world-record span of forty-two hundred feet between towers. The beginning of construction of the lesser-known structure took place in mid-1933, with President Franklin Roosevelt setting off a blast by remote control from Washington, and the first earth being turned up with a golden spade. At this ceremony, Herbert Hoover called the San Francisco-Oakland Bay Bridge “the greatest bridge yet erected by the human race,” yet until the 1989 earthquake it remained largely unknown outside the Bay Area, where it serves such an important transportation role. Among the reasons for its relative obscurity must also be counted the fact that this bridge had no single prominent and dominant dreamer like a Roebling, Lindenthal, Ammann, or Strauss serving as executive director and providing a visible personality to the project. Even its official name—San Francisco-Oakland Bay Bridge—is impersonal and awkward; it has often been abbreviated to the Transbay, or simply the Bay Bridge, the name by which it is best known locally.

  In spite of these differences, the Bay Bridge, like all great engineering projects, did encompass a long history of dreams and dreamers. Talk of having a bridge between San Francisco and Oakland began shortly after the Gold Rush and continued throughout the latter part of the nineteenth century. The 1906 earthquake distracted attention from a bridge, since the city had to be rebuilt, and in the meantime a ferry system carrying four million vehicles and fifty million passengers a year developed. Agitation for a bridge again arose, only to be suppressed by the world war. In the decade after the war, numerous applications for bridge-building franchises were filed, only to meet continuing opposition by the War Department, especially for a bridge north of Hunters Point, across the bay from Alameda. By the end of that decade, the progress of the Port of New York Authority in financing and constructing the 179th Street bridge across the Hudson had led to calls for a West Coast bridge supported by revenue bonds. A San Francisco Bay Bridge Commission was appointed by President Hoover, which seems ultimately to have made the objections of the War Department less absolute; the state highway engineer Charles H. Purcell was appointed as secretary.

  The San Francisco Bay area, showing the locations of the Carquinez Strait, Golden Gate, and San Francisco-Oakland Bay bridges (photo credit 6.6)

  Purcell was born in 1883 in North Bend, Nebraska, and attended Stanford and the University of Nebraska, where in 1906 he received his B.S. in civil engineering. He began working for the Union Pacific Railroad in Wyoming, then held positions in Nevada, New York, and Peru, with smelting, refining, and mining companies, before returning to construction and railroad work in the Pacific Northwest. In 1913, he joined the Oregon State Highway Department, which was then just forming, and became its first state bridge engineer. He accepted an appointment in 1917 as bridge engineer for the United States Bureau of Roads, and two years later became district engineer for the bureau, serving in Portland. He moved to California in 1927, to become state highway engineer there. Among the notable structures for which he was responsible is the Bixby Creek Bridge, located in the dramatic setting of the coast highway south of Carmel. This 330-foot reinforced-concrete arch, designed in conjunction with F. W. Panhorst, has been described as being “among the lightest and most graceful structures of this type in the United States.” But Purcell’s greatest achievement certainly has to be the San Francisco-Oakland Bay Bridge. His involvement with the project began when he and Charles E. Andrew, bridge engineer with the California State Highway Department, were placed in charge of “studies and investigations of engineering, location, and traffic” for a bay crossing.

  In the meantime, the state legislature had created a California Toll Bridge Authority, which provided the means for financing the project. Sound technical considerations regarding such important matters as foundations led Purcell and Andrew to recommend a bridge route from Rincon Hill in San Francisco to Yerba Buena Island, also known as Goat Island, which was occupied jointly by the U.S. Army, Navy, and Lighthouse services, and then on to Oakland. (The adjacent Treasure Island was to be created as the site of the 1939 exposition to commemorate the completion of both the Golden Gate and the San Francisco-Oakland Bay Bridge.) Including ap
proaches, the total length of such a bridge would exceed eight miles, half of which was over the bay; to cross each of the two stretches of water, engineers would have to devise independent structural solutions as great as any single major bridge then extant or under construction. After preliminary designs and underwater borings were made in 1930 and 1931, a San Francisco-Oakland Bay Bridge Division of the Department of Public Works was set up, with Purcell as chief engineer, Andrew as bridge engineer, and Glenn B. Woodruff as engineer of design. The board of consulting engineers comprised Ralph Modjeski, the chairman, who with J. Vipond Davies had made a preliminary survey for such a project a decade earlier; the partners Daniel E. Moran and Carlton S. Proctor; Leon Moisseiff; Charles Derleth, Jr.; and Henry J. Brunnier.