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

by Henry Petroski

  4

  In the early spring of 1890, a bill was passed in the U.S. House of Representatives, and by early summer in the Senate, authorizing the North River Bridge Company to begin construction within three years, and requiring it to complete the structure within ten years after it was begun. With the approval of Washington, no further action by the notoriously contentious state legislatures was needed, nor was it sought, though it might have helped generate more solid local support for the bridge. In the meantime, the Consolidated New York & New Jersey Bridge Company had been formed out of the old 1868 charter issued by New Jersey and a more recent one issued by New York. The consolidated company did not have the federal authority needed to cross the interstate waterway, however, and so Lindenthal’s North River company seemed to have the edge. Engineering News, comparing the two companies, noted that Consolidated had plans of which “the public has never seen even an outline,” although there were newspaper reports that “the big bridge is started.”

  In fact, a ground-breaking did occur on Christmas Eve, 1891, but “the circumstances attending the ceremony of turning the first sod were somewhat inauspicious,” for there was a pouring rainstorm, and the New York dignitaries and New Jersey delegates never did meet because of unclear directions to the site. However, even though some temporary trusswork was erected over an excavation for a tower on the Bergen County line, the company was believed to have had very little capital to proceed much further. It was reasonable to speculate, in fact, that Consolidated was hoping to have its charter bought out by the North River Bridge Company. Engineering News ridiculed the “spectacle” of “a few hackfuls of projectors trying in vain to find each other in the open country, turning over a single sod in a pouring rain storm,” but the journal was dead serious when it commented that it would be “sorry, indeed, to see any bridge design carried out in which symmetry and dignity of appearance are ignored, or in which the river channel is needlessly obstructed.” But two bridge companies continued to lay claim to charters for a Hudson River Bridge, and the similarities with the situation in St. Louis almost three decades earlier were not lost on close observers.

  There is often a good deal of uncertainty as to exactly where a great bridge will be built, not the least for reasons connected with raising the capital. Among the most costly of items can be the purchase of land for the piers, anchorages, and approaches to the bridge, and if the location of these was fixed too early in the planning stage, real-estate speculation could increase the cost manyfold. Thus, as Engineering News pointed out in comparing the styles of the rival companies:

  The North River Bridge Co. is wise enough to see that before an enterprise involving the expenditure of from $60,000,000 to $80,000,000 can be honestly and successfully launched something besides printer’s ink and wind is necessary. In enterprises of a great magnitude like this, everything depends, not upon the sale of isolated small blocks of stock to an uninformed public, but upon convincing great capitalists of the feasibility and future of the project. Before the latter can be done every detail of the plan must be worked out, every item of cost estimated upon sound data and traffic problems so carefully and exhaustively studied that the scheme can successfully stand the searching inquiry into its intrinsic merits that capitalists will surely inaugurate before putting money into it. It is worse than folly to invite general investment before this is done. And wide publicity of the exact location of proposed terminals and of other construction details is just the thing the business man will not seek until he has secured a considerable portion of the real estate necessary for his purposes. Nor will the promoter of a bona fide bridge take active steps in raising capital until he is fully informed as to the total cost of his scheme.

  As an engineer, Lindenthal may have been cautious to a fault, for good engineering also involves decisiveness and an ability to fix on best estimates and go ahead with the business of raising money and turning sod. The strategy of detailed engineering analysis and uncertainty of location, as articulated in the journal that had virtually become Lindenthal’s soapbox, was not exactly working. To give a sense of the obfuscation and the concomitant confusion that in some cases may have been deliberately introduced by both bridge companies during the years from 1886 to 1890, the location of the bridge was reported in various sources as terminating in Manhattan: “near Desbrosses St.” … “somewhere between Seventieth and Eightieth streets” … “at about Sixtieth St.” … “between 10th and 181st Sts.” … “between Washington Heights and Spuyten Duyvil” … “at Fourteenth-Street” … “at Fort Washington”… “at any point in the city of New-York” … “near 13th St.”… “about Forty-second St.”

  Financial conditions turned poor in 1893, and the prospects for any bridge across the Hudson looked bleak, especially as talk of tolls began to worry the railroad companies, among others. Cost of use was a real concern, for in early 1894 President Grover Cleveland had vetoed a bill that had passed Congress and that appeared to authorize the Consolidated New York & New Jersey Bridge Company to charge tolls on mail that passed over the proposed structure. The bill was vetoed also because it allowed for piers in the river, but they were still considered essential by those who did not believe a single span, suspended or not, to be possible.

  With rival factions continuing to propose conflicting solutions, Cleveland appointed a commission of engineering experts “to recommend what length of span, not less than 2,000 ft., would be safe and practicable for a railway bridge across the Hudson River, between 59th and 69th Sts.” The board comprised Louis Gustave F. Bouscaren, William H. Burr, Theodore Cooper, George S. Morison, and Colonel C. W. Raymond, “all well known to American engineers.” Bouscaren had been born on the island of Guadeloupe in 1840 and was an 1863 graduate of France’s Ecole Centrale des Arts et Manufactures. He had, among many other accomplishments, strengthened the cables of Roebling’s suspension bridge across the Ohio River at Cincinnati, and had built a railroad bridge across the Ohio that was at one time the longest truss span in the world. Burr, born in Watertown, Connecticut, in 1851, was an 1872 C.E. graduate of Rensselaer Polytechnic Institute who had taught at Rensselaer, worked as assistant to the chief engineer of the Phoenix Bridge Company, and taught civil engineering at Harvard before joining the faculty at Columbia. Cooper was, of course, at the peak of his career. Morison, born in Bedford, Massachusetts, in 1842, was educated at Phillips Exeter Academy and Harvard, from which he was an 1863 arts graduate and an 1866 law graduate. Though admitted to the New York Bar in 1866, he never practiced the legal profession. He did go on to gain extensive experience in bridge designing and building, however, beginning in 1867 with work in Kansas City under Octave Chanute on the bridge over the Missouri River at Kansas City. On his own, Morison had been engaged in many bridge projects, including the Cairo Bridge over the Ohio River, which was among the longest bridges in the world in the 1880s. Charles Walker Raymond had been born in 1842 in Hartford, Connecticut, and graduated in 1860 from the newly formed Collegiate and Polytechnic Institute of Brooklyn, where his father was professor of English language and literature, and entered West Point the following year. He had a distinguished career with the Corps of Engineers, including charge of the Mississippi River levees and work on important harbor improvements, and would go on to play a key role in supervising the design and construction of the Pennsylvania Railroad Company’s improvements in, under, and around New York City. It was Raymond (who had shown an early talent for mathematics) who was to draft the analytical discussion of the theory of suspension bridges contained in the report of the board over which he presided.

  Within three months of its appointment, the board reported that it was “of the unanimous opinion that a cantilever span of 3,100 ft. in the clear could be built and would be a safe structure,” but it would cost in excess of $50 million to cross the river thus without a pier. A pier in the center of the river would reduce the spans to two thousand feet and cut the cost of the bridge’s superstructure in half, but the foundations would
have to be dug to 260 feet below the water, which not only would be dangerous for the workers but also would add an uncertain amount of $10 million or so to the cost. A suspension bridge, with six tracks and a span of thirty-one hundred feet, could be built, it was thought, for about the same amount as the shorter-spanned cantilever. Furthermore, if a lighter bridge was acceptable, a safe but more flexible suspension bridge could be built for about $30 million. On balance, taking into account the uncertainty associated with digging deep foundations, the board concluded in favor of a suspension bridge.

  Another board of experts had been appointed earlier in 1894 by the secretary of war to look into questions relating to building bridges over navigable streams and, in particular, into the question of “the maximum length of span practicable for suspension bridges,” and to look into matters of “strength of materials, loads, foundations, wind pressure, oscillations and bracing.” The board comprised three members of the Corps of Engineers—then Major Raymond, and Captains William H. Bixby and Edward Burr—and its report acknowledged Lindenthal, Wilhelm Hildenbrand, and Leffert L. Buck, “for information and valuable suggestions.” Appendixes were contributed by Lindenthal (on temperature strains in hinged arches) and Josef Melan (on the theory of the stiffening girder). Clearly, the board of army engineers had gone into considerable technical depth in the nine months it took to prepare its classic report, which treated in detail matters of oscillation and other causes of failure in suspension bridges, and thus provided “one of the most valuable and instructive engineering investigations of the day … in a field that has hitherto been practically unexplored,” according to Engineering News. The conclusion of the board was that a six-track suspension bridge of thirty-two-hundred foot main span was practicable at an estimated cost of $23 million, and that traffic in 1894 warranted such a bridge, although it should be so constructed that its capacity could be increased in the future, as needed. In addition to addressing the Hudson River problem, the board had looked at the more general feasibility question, and concluded also that it was possible to build a suspension span as long as 4,335 feet.

  Though the report of the army engineers removed technical objections to the suspension bridge, it did not fully dispose of financial objections. Indeed, even Engineering News admitted that, whereas it had been projected that there was rail traffic enough to cover the actual construction cost, it was not clear that the bridge could “attract a traffic sufficient to pay the interest on its cost.” The Consolidated New York & New Jersey Bridge Company challenged the objections to a pier in the river, and also questioned whether the foundation for such a pier had to be dug so deep and therefore had to be so expensive as was feared, but the secretary of war continued to rule in favor of a suspension bridge. The argument for a cantilever did not end, however, in part because of the success of the Forth Bridge and in part because of the vulnerability of the suspension-bridge type to attack. Traffic on Brooklyn Bridge was an ongoing problem, aggravated in part by the structure’s inability to carry heavy engines, thus requiring that cable cars be used on the bridge, and switching them about at the terminals presented an endless scheduling and capacity problem. To make matters worse, the bridge that had been held up as the counterexample to the persistent belief that suspension bridges could not carry railroad traffic, John Roebling’s Niagara Gorge Bridge, was in the process of being replaced—and a cantilever was being proposed. The forty-year-old landmark bridge was showing signs of wear, and the weight of railroad trains had increased considerably since it was built. In reporting this development, the praise of Engineering News sounded faint indeed:

  To Mr. Roebling belongs all the credit for teaching engineers how to use wire in this form in a railway bridge; and that his connections were faulty in the light of modern practice, and that his stiffening truss was no such truss at all, does not detract from his boldness as an engineer and the services he performed in developing the manufacture of wire in this country.

  The cantilever was well suited to the eight-hundred-foot span over the Niagara Gorge, and it would be the “cheaper, stiffer, and better structure,” admitted Engineering News, but the suspension bridge was still the bridge of choice for spans on the order of three thousand feet.

  The recent competition for a bridge over the Danube at Budapest was cited as an indication that “engineers are only now beginning to more carefully study the principles and details of suspension bridge construction.” Indeed, first prize in that competition went to a thousand-foot-main-span wire-cable suspension bridge, but the design did not receive the bonus prize money that would have been awarded had the cost of the bridge not exceeded $1 million. In fact, the bridge—whose land spans looked like the side aisles of a Gothic cathedral, and whose tollbooths were built over the anchorages, also forming pedestals for equestrian statues—was estimated to cost almost twice that amount. Second and third places went to some very handsome cantilever designs, one of which looked like a suspension bridge in profile, and each of which was estimated to cost under $1 million. Of the remaining seventy-odd designs that were submitted from Europe and America, three additional ones were bought for possible use in Budapest. Among these was a chain suspension bridge, the only design of its kind submitted. This bridge and the top three winners were illustrated in Engineering News in 1894; the journal unfortunately used words alone to describe some others, “which seemed to be intended only to furnish amusement to the jurors in their arduous work”:

  One design for a one-span bridge at Eskuter shows curiously curved trusses, freely resting on abutments. The widely separated chords of the trusses are stiffened by enormous rings, and are ornamented by a legion of saints’ statues. The wagon traffic moves over a suspended roadway, while the foot passengers climb over the bold curve of the top chord. Another fantastic design consisted of an iron tube of 1,020 ft. span, made up of Mannesmann tubes placed parallel and connected with each other by iron bars, riveted in spirals to the tubes.

  As Engineering News was to editorialize, on the occasion of the replacement of the Niagara Gorge Suspension Bridge with a stiffer steel structure, “there is no knowing to what flights over space the bridge of the future may attain.” Money was admitted to be the limiting factor. In bridging the Hudson, the question was not of money alone, however, for the secretary of war would simply not approve a cantilever design with a pier in the river. The Consolidated New York & New Jersey Bridge Company thus asked Theodore Cooper, its consulting engineer, to prepare specifications for a suspension-bridge design. Since he had never designed such a bridge himself, his specifications only covered such things as the load the bridge was to carry, the foundation conditions, and materials of construction. Bidders were invited to select the geometrical outlines, and Cooper’s firm leaned toward the design of the Union Bridge Company, which guaranteed to build for no more than $25 million a 3,110-foot span with “immense rigid trusses” supported by twelve cables. The design was that of Charles MacDonald, organizer and president of Union, who had been born in Ontario, Canada, in 1837. After working on surveys for the Grand Trunk railroads, he entered the United States in 1854, immediately began studies at Rensselaer Institute, and received a degree in civil engineering in 1857. Among much other railroad and bridge-building experience, Mac Donald supervised the design of the great cantilever bridge across the Hudson at Poughkeepsie, but his suspension-bridge design for the New York crossing was an unharmonious concoction.

  Lindenthal’s North River Bridge Company was denying rumors that it was going to relinquish its charter, which was to expire in mid-1895, “unless something were done by that time showing the sincere purpose of the company to construct the work for which they have obtained powers.” The company claimed that “work had quietly commenced some time ago upon the New Jersey anchorage,” and that it had spent more money acquiring property and advancing the plans than its rival. In fact, according to a cornerstone reportedly snatched from the jaws of destruction almost a century later by Lindenthal’s grandson, ground was
indeed broken on June 8, 1895, and the first foundation masonry was laid at the site of the Hoboken anchorage, opposite Manhattan’s 23rd Street. What was needed back then, however, was not ceremony but $21 million for the bridge proper and $15 million for property and accessories, which was admitted to be “an enormous sum of money, and the financiering of the bridge far exceeds in difficulty the engineering problems presented, unprecedented as these last are.”

  In the meantime, support was growing for completing construction of a tunnel under the Hudson, since the bridge companies continued to focus on elevated approaches, which was the costlier method of getting railroads into the city. Late in 1897, an editorial in Engineering News accused the bridge promoters of failing “to appreciate the fact that it is the suburban traffic, and practically that alone, on which their structures must depend for income” from tolls. The journal, which after the death of Wellington had no longer simply embraced Lindenthal’s ideas, had become a voice of reason. In a letter challenging the editorial, Lindenthal simply reiterated his position on the bridge, which pretty much everyone by then knew, or was expected to know. But there were alternatives.

  The Hudson Tunnel Railroad Company had been chartered in 1873, and ground was broken the following year. There were to be two tunnels, each containing a single track, but opposition lawsuits delayed the work until the end of the decade, and work was stopped in 1882, after over a million dollars had been spent but no more money could be raised in America. John Fowler and Benjamin Baker were approached in late 1887 and asked if they thought the tunnels could be completed for the amounts American contractors were estimating—namely, $900,000 for one tube and $1.2 million for the other. After consulting European tunnel engineers, and after a visit to the unique New York site by Baker, who inspected the books of the contractors to understand the cost of American labor, the designers of the incomplete but already famous Forth Bridge gave their support to the Hudson River tunnel scheme, which brought $1.5 million of British money into the project.