By: Robert W. Jackson
In 1868 the Keystone Bridge Company erected a railroad bridge across the Mississippi River connecting Dunleith (now East Dubuque), Illinois, and Dubuque, Iowa. The Dunleith and Dubuque Bridge was a crucial link between eastern and western railroad systems and a notable example of post-Civil War bridge-building technology. Four years later, in 1872, the company replaced the original western (Dubuque) approach trestle with seven identical iron spans built to the same general specifications of the main bridge. Three of those spans still exist. Together, they are historically significant and rare artifacts of an important era in the nation’s economic and industrial development. | |
| Introduction | |
| The end of the Civil War in 1865 marked the beginning of an explosive era of railroad construction in the trans-Mississippi West. The sectional conflicts that had hampered western railroad expansion before the war were laid to rest along with the dashed hopes of southern secessionists. Full economic exploitation of the vast area lying between the Mississippi River and the west coast of the reunited nation was dependent, however, on the ability of a small number of bridge-building firms that possessed the technological expertise and business acumen to erect long-span railroad bridges across major western rivers. With the exception of the extensively altered Eads Bridge in St. Louis (1874), none of the great Mississippi and Missouri river bridges built in the 1860s and 1870s survive. Remnants exist, including three extant approach spans of the fifth railroad bridge across the Mississippi River, the Dunleith and Dubuque Bridge (1868). These spans, built to the same general specifications as the main bridge that they served, were all originally designed as 93-foot, eight-panel, pin-connected, cast- and wrought-iron Pratt through trusses, featuring the patented Keystone column in their main compression members. The Keystone Bridge Company of Pittsburg, Pennsylvania, fabricated and erected them in 1872 to replace the original wood approach trestle on the west (Dubuque) side of the river. Their distinctive design characteristics, method of construction, association with one of the most important Mississippi River crossings, and rarity as surviving products of the Keystone Bridge Company make them worthy objects of study for industrial archaeologists. | 1 |
| Background | |
| The Rock Island Bridge, connecting Rock Island, Illinois, and Davenport, Iowa, was the first railroad bridge across the Father of Waters when it opened to traffic in 1856. The Rock Island Bridge Company, a bridge financing organization controlled by officers of the Chicago and Rock Island Railroad, contracted with the Stone and Boomer Bridge Company of Chicago, Illinois, to build the superstructure of the bridge. Railroad crews and local contractors built the substructure. | 2 |
| The Albany Iron and Machine Works, contractor for the Chicago and North Western Railway, completed the second Mississippi River railroad bridge in 1865. This structure connected Clinton, Iowa, and Fulton, Illinois. As was the case with the Rock Island Bridge, the Clinton Bridge was composed mainly of wood trusses and included a swing span for the passage of boat traffic. Like the Rock Island Bridge, it was also a serious obstruction to navigation and was erected without the approval of the federal government. | 3 |
| Well before erection of the Rock Island Bridge, the United States War Department and the Congress of the United States had begun to recognize the need for federal control over the erection of bridges across the major navigable waters of the nation. Construction of railroad bridges across the Ohio River, beginning with the Wheeling and Belmont Bridge in 1849 had brought this need to the forefront of public debate. Since any bridge across the river, even a suspension bridge with no supporting piers in the stream, threatened the economic livelihood of steamboat operators, it was imperative for the federal government to address the competing interests of waterborne and railborne transportation. | 4 |
| The urgent need for a bridge over the Ohio River at Wheeling, Virginia (became Wheeling, West Virginia after statehood in 1863), had become apparent soon after the Cumberland Road (National Road) reached the banks of the river in 1817. Ferry service at this time was unreliable, dangerous, and frequently unavailable due to ice in the river. In anticipation of the completion of the road, acts were passed in Ohio and Virginia in 1816 authorizing the creation of a bridge company, provided the bridge built would not become an obstruction to navigation. Ten years were allowed for its erection, but after 19 years no action had been taken towards construction. In 1836 the State of Virginia passed another act providing for the reorganization of the bridge company, and the State of Ohio extended the time for completion by another 10 years. | 5 |
| In the same year, a petition was presented to Congress requesting federal authorization for a bridge at Wheeling, but despite strong support in both sessions of the Twenty-Fourth Congress, the effort was not successful. The right of Congress to provide such authorization had previously been upheld by the U.S. Supreme Court in the case of Gibbons v. Ogden (1824), which affirmed that federal authority over interstate commerce included river navigation. Despite failure of the petition, the debate generated at this time served to illustrate the concerns of Congress, the U.S. Army Corps of Engineers, and steamboat owners about bridges over navigable waterways; these concerns would later be addressed in more depth as agitation increased for congressional approval of bridges across the Mississippi and Missouri rivers. | 6 |
| Following the lack of action by Congress, the legislature of Virginia passed another act in 1847 that revived and continued certain parts of the acts passed in 1816 and 1836. This action led to a suit to enjoin the construction of the Wheeling Bridge, filed by the Commonwealth of Pennsylvania on 28 July 1849 with the U.S. Circuit Court in Philadelphia. The case, which was transferred in August to the U.S. Supreme Court, attracted the attention of bridge engineers and railroad corporation executives across the country. They knew that an important shift had taken place in the battle between water-oriented and rail-oriented commercial interests. The field of conflict had moved from the legislative branch of government to the judicial, and the economic future of the country was at stake. | 7 |
| The case of Pennsylvania v. Wheeling and Belmont Bridge Company came before the U.S. Supreme Court during the January term in 1850, but the Court immediately referred the case to a commissioner to determine if the bridge was an obstruction to navigation. The commissioner determined that the bridge was indeed an obstruction and that changes to its design were necessary. The Court agreed and ordered the changes to be made, but on 31 August 1852, Congress enacted a law that declared the bridge to be a lawful structure as originally designed and established it as a post road for the passage of the mails of the United States. The law also stated that the officers and crews of all watercraft navigating the Ohio River were required to regulate the use of their boats so as not to interfere with the bridge.1 This constituted the first real acknowledgement by Congress that waterborne commerce would have to make some allowance for the challenge posed by application of steam technology to another mode of transportation. Because the legislation was specific to the Wheeling and Belmont Bridge, the larger issues remained to be resolved as the lines of various Chicago-based railroad companies reached the next major water obstacle to westward expansion, the Mississippi River. | 8 |
| The Chicago and Rock Island Railroad was the first, completing a line to the eastern bank of the Mississippi River, across from Davenport, Iowa, in February 1854. The Galena and Chicago Union Railroad (later merged with the Chicago and North Western Railroad) arrived in Fulton, Illinois, nearly opposite Clinton, Iowa, in 1855, and was followed shortly thereafter by the Illinois Central Railroad, which reached Dunleith, Illinois, opposite Dubuque, Iowa, in the same year. By 1857, seven Chicago-based railroads had lines terminating on the eastern bank of the river. In each case, the railroad corporations had already secured passage of acts in the legislatures of Illinois and Iowa that authorized the creation of separate companies having the right to construct bridges with one end in the respective state. No authorization for bridge construction was sought from the federal government, however, which eventually led to several challenges in federal courts during the mid- to late 1850s of the right of these bridge companies to erect obstructions to free navigation of the nation’s rivers. | 9 |
| The court cases were inconclusive and mainly served to illuminate the need for decisive action on the part of Congress to establish such rights. But southern congressmen, seeing little benefit to their constituencies by the advance of northern railroads, successfully blocked any attempts at resolution of the issue. The Civil War changed all that. The defeat of the South in 1865 also meant a victory for northern railroad corporations and the bridge financing companies that they controlled. By the end of the year, three bills filed in Congress authorized bridges across the Mississippi, and more were to follow. In contrast to its prewar inability to act, Congress moved swiftly and passed the enabling legislation within one-half year. | 10 |
| On 25 July 1866, President Andrew Johnson signed into law an act authorizing construction of bridges across the Mississippi River at Winona, Minnesota; Prairie du Chien, Wisconsin; Dubuque, Iowa; Burlington, Iowa; Quincy, Illinois; Keokuk, Iowa; Hannibal, Missouri; and St. Louis, Missouri. A special clause also authorized a bridge across the Missouri River at Kansas City, Missouri. Passage of this act not only facilitated full economic exploitation of the trans-Mississippi West by railroad corporations but also initiated a fierce rivalry among the relatively small number of bridge building companies then possessing the ability to construct long-span railroad bridges. | 11 |
| Bridge financing corporations acting as general contractors built the Rock Island and Clinton bridges, with engineers of the controlling railroads serving as overseers of construction. After the Civil War, business practice began to favor companies that could design, fabricate, and erect all-metal superstructures, while also acting as general contractors to oversee the entire construction effort for the bridge financing corporation. One of the most successful of these organizations was the Keystone Bridge Company of Pittsburgh, Pennsylvania. | 12 |
| The Dunleith and Dubuque Bridge | |
| Early in January 1868, budding industrialist Andrew Carnegie and Keystone Bridge Company engineer Walter Kattè arrived at the terminus of the Illinois Central Railroad tracks on the east bank of the Mississippi River at Dunleith, Illinois (later renamed East Dubuque), just across the frozen river from Dubuque, Iowa. Carnegie was vice president of (and partner in) Keystone, a firm he created in 1865 by renaming and reorganizing the Piper and Shiffler Bridge Company. Carnegie organized the earlier company in 1862 to profit from the growing demand for iron railroad bridges. By bringing in new investors and capital to create Keystone, Carnegie established a firm that was to become, as he stated later in his life, “my pet as being the parent of all the other works.”2 | 13 |
| Carnegie felt that his and Kattè’s presence in Dubuque was crucial to the success of Keystone’s efforts to win the contract for erection of the superstructure of the Dubuque Bridge; the contract would play a pivotal role in his plans to control certain aspects of the trans-Mississippi expansion of the nation’s rail network. Moreover, building the bridge, which Carnegie characterized as “the most important railway bridge that had been built up to that time,” would establish Keystone as the major builder of iron railroad spans for Mississippi and Missouri river bridges.3 | 14 |
| Carnegie and Kattè crossed the river in a four-horse sleigh and arrived in Dubuque, only to find that the board of directors of the Dunleith and Dubuque Bridge Company (the organization created to finance, construct, and operate the proposed bridge) had already decided to award the contract for construction of both the superstructure and substructure to the low bidder, Lucius B. Boomer of Chicago. Boomer, who had reorganized the Stone and Boomer Bridge Company into a sole proprietorship about a year after completing the Rock Island Bridge, was one of Carnegie’s main rivals for the lucrative business of building long-span railroad bridges. | 15 |
| Despite the board’s decision, Carnegie was not about to give up such an important contract without a fight. He went to work on the directors, finding them to be “delightfully ignorant of the merits of cast and wrought-iron. We had always made the upper chord of the bridge of the latter, while our rival’s was made of cast-iron. This furnished my text.” Picturing the results of a steamboat striking a bridge made entirely of cast iron, as opposed to one made of cast- and wrought iron, he claimed that “in the case of the wrought-iron chord it would probably only bend; in the case of the cast-iron it would certainly break and down would come the bridge.”4 | 16 |
| By referring to the possibility of bridge failure, Carnegie touched on the one point of concern that was more important to the bridge company directors than the matter of cost. Railroad bridges had been falling down at an alarming rate, and the bridges across the major navigable rivers were thought to be particularly prone to disaster.5 The Rock Island Bridge, for example, had been temporarily put out of operation shortly after completion as a result of being struck by the Effie Afton, a steamboat on its maiden voyage out of St. Louis. Several boats and barges had also struck the Clinton Bridge, albeit without the same dire results as at Rock Island. Moreover, the directors were aware that the 1855 collapse of a Boomer-built bridge over the Gasconade River near Hermann, Missouri, had killed 43 people and injured another 70. | 17 |
| Platt Smith, the most influential and powerful of the bridge company directors, reinforced Carnegie’s argument by relating how, on a recent cold night, he had run his buggy against a cast-iron lamp post, which subsequently shattered into pieces. Seizing the moment, Carnegie exclaimed, “Ah, gentlemen, there is the point. A little more money and you could have had the indestructible wrought-iron and your bridge would stand against any steamboat. We never have and never will build a cheap bridge. Ours don’t fall.”6 | 18 |
| The directors proved to be as shrewd as Carnegie and informed him that Keystone could have the contract, if he built the bridge for the price bid by Boomer. Carnegie agreed, and after the bids were officially opened on 13 January 1868, the Keystone Bridge Company was awarded the contract for superstructure construction. The contract for substructure construction was awarded to Reynolds, Saulpaugh and Company of Rock Island, Illinois. | 19 |
| The contract between the Keystone Bridge Company and the Dunleith and Dubuque Bridge Company, signed on 14 January 1868 was for $283,550. The contract signed the same day with Reynolds, Saulpaugh and Company was not for a fixed price but was tied to a schedule of prices per unit of materials, with the quantity of materials to be determined during construction. Colonel Roswell B. Mason, chief engineer of the Dunleith and Dubuque Bridge Company, drew up the general specifications of the bridge, while the specific design of the superstructure would be left to Jacob H. Linville, president of the Keystone Bridge Company and its most experienced bridge engineer. | 20 |
| Flush with his success in securing the Dubuque contract, Carnegie returned to Pittsburgh and composed a letter to Linville and the directors of Keystone. Dated 25 January 1868, the letter begged Carnegie’s associates to consider that “the success of Iron Bridging has attracted the attention of several parties who are anxious for an opportunity to embark on it. Among those may be mentioned Reeves [a reference to David or Samuel Reeves of the Phoenix Iron Company, which was soon to organize its bridge-building operations as Kellogg, Clarke and Company, later reorganized as Clark, Reeves and Company in 1871], Jones [a reference to Jones, Haskell and Company, proprietors of the Albany Iron and Machine Works], Boomer & c—all of whom are trying to secure an important work upon which to found [a] reputation.” If Keystone could not compete with these companies due to a lack of plant capacity, it would permanently miss an opportunity to take the lead position in an important and developing sector of industrial activity. As Carnegie noted, “There is only one way of defeating these parties & that is to place ourselves in position to bid for & construct the Iron Bridging already concluded upon and certain to be built by somebody.”7 | 21 |
| Carnegie stated that the cost of creating reserve machine and blacksmith shop capacity, beyond that required for the work then under contract, would be the most valuable investment the company could make. Citing numerous bridge contracts likely to come up for bids in the near future, he warned that unless the firm took prompt action it would be unable to bid on those jobs: “I for one am not willing any longer to shoulder the responsibility of neglecting to act in this matter.”8 | 22 |
| Without meaning to insult those who were then managing the company (meaning Linville, John Piper, Aaron Shiffler, and Carnegie’s brother Thomas, the company’s treasurer), Carnegie insisted that their views regarding the future of “iron bridging” were far too narrow. He claimed, they “fail to see that it is only in its infancy in this country.” He urged an expansion of plant facilities by construction of a larger blacksmith shop, the purchase of new machinery for the machine shop, the acquisition of land across the Allegheny River for a new foundry and additional fitting shops, and a change in plant personnel.9 | 23 |
| It was not until 1872, however, that the plans for expansion envisioned by Carnegie happened. In that year, the legislature of the Commonwealth of Pennsylvania authorized the Keystone Bridge Company to increase its capital stock to $1.5 million. It shortly thereafter erected new facilities of increased capacity on a tract of land of about six acres, including machine shops, blacksmith shops, riveting sheds, bolt cutting and testing houses, pattern shops, a large foundry, offices, and stables.10 Boomer recognized the same need for increased capacity and was able to move much faster than Carnegie. In November 1868, he began building a new facility at the corner of Eagan and Stewart avenues in Chicago. In 1870 he reorganized his bridge building operation as the American Bridge Company, and by 1876 the firm had more than 3 acres under roof on a site that encompassed about 35 acres.11 Other competitors followed suit. In 1870 the blast furnaces, rolling mills, and shops of Clarke, Reeves and Company occupied about 30 acres in Phoenixville, Pennsylvania. After the death of David Reeves in 1871, Samuel J. Reeves succeeded to the presidency of the company and began construction of a new rolling mill in 1872, which eventually exceeded the size of those built by rival companies.12 | 24 |
| Shortly after the trip to Dubuque in January 1868, Carnegie sent Kattè to Chicago to open up a branch office of the Keystone Bridge Company and the Union Iron Mills (the Carnegie-controlled supplier of iron to Keystone) on Dearborn Street, virtually on Boomer’s doorstep. By so doing, Carnegie hoped to position his firm to take advantage of the fact that Chicago-based railroads were the most aggressive of all railroad corporations in planning for the erection of bridges across the Mississippi and Missouri rivers. Keystone was already losing ground to its rivals.13 | 25 |
| The Detroit Bridge and Iron Works won the contract for erection of the all-iron Chicago, Burlington and Quincy (CB&Q;) Bridge at Burlington, Iowa, which was completed in July 1868. It was the first of the federally authorized Mississippi River bridges to be erected. The nearly identical CB&Q; Bridge at Quincy, Illinois, erected by the same company, followed shortly thereafter. | 26 |
| Further south, Carnegie and Boomer were the main competitors for the very lucrative St. Louis Bridge contract. Their battle over the right to build the greatest of all Mississippi River bridges (which later would become the first long-span bridge in world history to use significant amounts of steel) was an epic contest that continued over the course of several years. Carnegie eventually won the St. Louis job and triumphed in winning the contracts for other bridges on the list approved by Congress in 1866, including the bridges at Kansas City (1868) and Keokuk (1871). Keystone also built two spans of the rebuilt bridge across the Mississippi River at Clinton, Iowa (1869), and constructed the superstructure of the Mississippi River High Bridge at St. Paul, Minnesota (1887). After losing out to Carnegie in St. Louis, Boomer moved on to build a number of other structures for railroad companies and became the chief bridge builder for the Union Pacific Railroad. It was in connection with his responsibilities for that company that he once again crossed paths with Carnegie. | 27 |
| In 1872 Carnegie’s Keystone Bridge Company was called in to help Union Pacific Railroad engineers complete a bridge across the Missouri River between Omaha, Nebraska, and Council Bluffs, Iowa. The superstructure of that bridge rested on piers put in place by Boomer’s American Bridge Company and used Post trusses that had originally been ordered by Boomer. The work initiated by Boomer had come to a stop, however, when it was discovered that the charter of the railroad only allowed it to build west from Omaha, not to cross the river east to Iowa. The charter of the railroad company was eventually amended to allow for construction of the bridge, and the American Bridge Company featured the structure in its promotional literature for many years after its erection, without acknowledging that one of the company’s main rivals had completed the work. | 28 |
| All that was in the future, however, and in 1868 the Keystone Bridge Company already had more than adequate capacity to build the Dunleith and Dubuque Bridge. Problems with erection of the superstructure were relatively minor, and construction of the third “all metal truss” railroad bridge erected across the Mississippi River (the CB&Q; bridges being the first and second) was completed in December 1868, one month ahead of schedule at a total cost of about $800,000. Although functional needs were paramount in its design, the western portal included ornamental details of a type sometimes found on railroad bridges located adjacent to a town (see Figure 1). Despite the desire of Dubuque residents that it accommodate wagon and pedestrian traffic, the bridge was constructed for railway use only, as were all the previous Mississippi River bridges built by the railroads. A sign placed on an end post of its Dubuque entrance telling people to “Keep off the Bridge” was less than successful, and pedestrians occasionally used the bridge to cross between Iowa and Illinois.14 | 29 |
| Figure 1. Main spans of the Dunleith and Dubuque Bridge, looking east, date unknown. Used with permission, Center for Dubuque History, Loras College, Dubuque, Iowa. | |
| The Approach Spans | |
| The approximately 1,760-foot main bridge structure was originally accessible on the west (Dubuque) end by a long wood trestle approach of about 2,400 feet that crossed the sloughs between Sixth Street and the bridge. At a meeting held in January 1870, the Dunleith and Dubuque Bridge Company board of directors resolved to fill some of the low ground between Sixth Street and the bridge and to erect twin iron bridges over a portion of the sloughs, thus partially eliminating the wood trestle. No action was taken, however, and the following year a decision to completely remove the trestle resulted in a contract with the Keystone Bridge Company for eight identical cast- and wrought-iron, eight panel, pin-connected Pratt through-truss approach spans, each about 93 feet long, built in accordance with the same general specifications as the main bridge spans. | 30 |
| The design and method of construction of these spans is significant, primarily, for two reasons: first, their lower chords were formed of forged wrought-iron eye bars with upset heads; second, they featured the distinctive cylindrical “Keystone column” compression members for their inclined end posts and vertical posts, each composed of four rolled wrought-iron segments, riveted together at the flanges, with cylindrical spacers between each member. | 31 |
| In 1861, Linville built an iron bridge on the Delaware extension of the Pennsylvania Railroad over the Schuylkill River, near the U.S. Arsenal at Philadelphia. This marked the first use of wide forged wrought-iron eye bars that have enlarged ends made by compressing the hot iron into molds under immense pressure. On 14 January 1862, Linville and Piper were granted a patent (no. 34,183) for this method of construction, and on 31 October 1865, they were awarded a second patent (no. 50,723) for an improvement of this method, which they claimed increased the density, toughness, and strength of the enlarged ends. It also permitted the holes or eyes for the connecting pins to be cut out without rendering the transverse section at the eye less than that of the other parts of the bar, or diminishing the transverse or longitudinal strength of the chord bar.15 This method of forming the lower chord eye bars became one of the distinctive features of American bridge construction.16 | 32 |
| The bridge built by Linville in 1861 also employed the first wrought-iron hollow compression columns of specially rolled shapes, but many years passed before Linville was awarded a patent for columns made of sections, united by transversely intersecting tie bolts. Linville claimed that this design “was the only form of strut offering uniform resistance to flexure, transversely, in every direction, and affording the highest resistance with the least expenditure of material.” Moreover, by using intersecting tie bolts of varying length, thus increasing the diameter of the column at the center, “greater resistance to flexure is obtained, and the openings between the sections allow the interior of the column to be painted.”17 | 33 |
| The Keystone column was similar to the Phoenix column patented by Samuel Reeves on 17 June 1862.18 Whereas the Phoenix column was of uniform width throughout its length, the Keystone Column, through use of spacers of varying lengths, was wider in the middle than at the ends. Moreover, it was Linville’s contention that the incorporation of flanges, as in the Phoenix column, though “convenient in securing the edges, does not materially increase the lateral stiffness in the direction of the diameter taken midway between the flanges. The material in the flanges would therefore be more economically disposed by increasing the diameter or thickness of the shell.”19 | 34 |
| Whatever were the merits claimed by the manufacturers, the greatest difference seen in these two types of cylindrical columns in surviving iron bridges is in the ease of inspection and maintenance. The Phoenix column had a cap on the top that was supposed to prevent water from seeping into the column and corroding it from within. The condition of surviving bridges with Phoenix columns suggests that the caps have done their job fairly well over time, but the possibility of inner corrosion always exists in spans that have long exceeded their original design life. Unlike with the Phoenix column, the interior of the Keystone column, due to the inclusion of spacers between the main column members, can easily be inspected for corrosion and painted when needed. In the 1860s, however, bridge buyers were not interested in the ability of a particular design to last into the 21st century; they were only concerned with the cost and functional reliability of a bridge that was designed to last a few decades. | 35 |
| The 1871 contract between the Keystone Bridge Company and the Dunleith and Dubuque Bridge Company for the eight approach spans was for $45,000. Reynolds, Saulpaugh and Company won the contract for preparation of the substructure, which probably included draining the sloughs, at an estimated cost of $55,000. A change in the location of the approach spans resulted in a decrease in the number required, and only seven spans were eventually erected in January 1872 at a total cost of $131,250 (see Figure 2). The final cost probably exceeded estimates due to difficulties experienced in preparing the site. No savings occurred by reducing the number of spans erected because the bridge company had already committed to the purchase of eight spans and had to pay for all spans that were ordered. The unassembled components of the eighth span were stored until finally disposed of in November 1874 when the span was sold to the CB&Q; Railroad for use on the Turkey River branch of the subsidiary Chicago, Dubuque and Minnesota Railroad. This span, erected over the Volga River in Clayton County, Iowa, was sold for $2,686.30, even though CB&Q; president James M. Walker complained to Caleb H. Booth, secretary of the Dunleith and Dubuque Bridge Company, that he could buy a wood bridge of the same length for only $2,100.20 The cost represented the value of the like-new fabricated bridge components but probably did not include any costs associated with erection on site. | 36 |
| Figure 2. Detail from “Birds Eye View of the City of Dubuque Iowa 1872,” by Augustus Koch, showing approach spans of the Dunleith and Dubuque Bridge. Used with permission, Center for Dubuque History, Loras College, Dubuque, Iowa. | |
| On Saturday, 13 January 1872, the seven erected approach spans of the Dubuque Bridge were tested according to the common practice of the time. Two locomotives of the Illinois Central Railroad (the main lessee of the bridge), tenders fully loaded with coal and water, were slowly driven onto each span in succession from east to west and then stopped, making a stationary load of about one ton per linear foot of bridge. The deflection of each span was then recorded. It also was found, by measurement taken under span number five, that when the train was moving at a rate of about 15 miles per hour, the deflection of the span was only about 1¼32 inch more than when measured under the stationary load. All spans passed the test, and the new approach was put into service (see Figure 3).21 | 37 |
| Figure 3. Approach spans of the Dunleith and Dubuque Bridge, looking east, date unknown. Used with permission, Center for Dubuque History, Loras College, Dubuque, Iowa. | |
| A measure of how the work performed by Keystone on the Dubuque approach spans compared with that of other firms comes from an 1880 inspection report by George Morison, who served as assistant engineer on construction of the first bridge across the Missouri River at Kansas City, Missouri (completed in 1869) and who later would become one of the nation’s foremost bridge engineers. In March 1880, a little more than eight years after the Dubuque approach spans were erected, Morison, on leave from his duties as chief engineer of the bridge then being erected over the Missouri River at Plattsmouth, Nebraska, inspected the Dubuque Bridge at the request of the bridge owners. His preliminary report to Dunleith and Dubuque Bridge Company President William Boyd Allison, written on 23 March 1880, stated that the bridge compared favorably with similar structures erected at about the same time, even though the details of design and construction were generally inferior to those currently employed. He also noted that the fixed spans were decidedly better than those on the Quincy and Burlington bridges, although the swing spans of those two bridges were superior to the swing span of the Dubuque Bridge.22 | 38 |
| Concerning the approach spans of the Dubuque Bridge, Morison noted in his final report, dated 18 June 1880, that because they were erected later than those of the main bridge, the details of design and construction represented a slightly more advanced practice. In particular, he found that the connections of the posts and laterals were made with pins at the top chord, as opposed to being made with washer plates and screws, as in the main bridge (see Figure 4). The principal defect of the approach spans, Morison claimed, was not in their design but, rather, in the method of fabricating the tension members. These were in all cases square bars on which the eyes were formed by bending the rods round and welding the backs (see Figures 5 and 6). This caused the bars to be of varying lengths, thus creating a difference in the strain borne by each bar. In several places, Morison found that one bar would hang loosely, receiving no strain except when the spans were subject to a live load (i.e., when a train was moving over the bridge). The bar should have been accurately bored, he reported, so that any two bars placed side by side would be of the same length and thus subject to equal strain. | 39 |
| Figure 4. Connection details at midspan, White Water Creek Bridge. Illustration from HABS/HAER Collection, HAER Iowa-31, Prints and Photographs Division, Library of Congress, Washington, DC; delineation by Caroline Schweyer. | |
| Figure 5. Detail showing lower chord connections, Cloie Branch Bridge. Photo by Makela Mangrich, 2001. | |
| Figure 6. Detail of bottom connections of White Water Creek Bridge from below, 1995. Photo from HABS/HAER Collection, HAER Iowa-31, Prints and Photographs Division, Library of Congress, Washington, DC. | |
| Morison also noted that the floor beams of the approach spans consisted of two 15-inch beams of the same weight as the fixed spans of the main bridge, suspended from the pins. The hangers were 11¼2-inches square and had an aggregate section of 9-inches square (see Figure 7). This section was little more than half that of the hangers of the main bridge fixed spans but was deemed adequate for the class of rolling stock then in use and safe for much heavier loads. | 40 |
| Figure 7. Detail of bearing plate at inclined end post, Cloie Branch Bridge. Photo by Makela Mangrich, 2001. | |
| Morison’s chief concern was that design of the floor system of the bridge was inadequate because the ties were too far apart and improperly secured to prevent a derailed train from breaking through the floor. This failure to account for damage resulting from derailment was a matter of great concern to Morison and cited by him as a factor that had only recently received the attention by bridge designers that it deserved. Except for this aspect of the floor design, however, Morison found the Dunleith and Dubuque Bridge to be well designed.23 | 41 |
| In 1887, the same year that a wagon and pedestrian bridge (the Dubuque High Bridge) was completed immediately adjacent to the railroad bridge (see Figure 8), the City of Dubuque and the Illinois Central Railroad began spending a considerable amount of money on infrastructure improvements in Dubuque. These improvements included construction of a new rail passenger station and filling of the low ground next to the river. As the sloughs were gradually eliminated over the ensuing years, the approach spans were removed, which created a challenge for the bridge company. It had to find a way to recover a portion of the capital expenditure by finding buyers for the spans, still in good condition and perfectly serviceable. | 42 |
| Figure 8. Dunleith and Dubuque Bridge, and Dubuque High Bridge under construction, looking northwest, date unknown. Used with permission, Center for Dubuque History, Loras College, Dubuque, Iowa. | |
| The era of the iron railway bridge was rapidly nearing an end, and steel would soon become the preferred metal for new railroad bridges. Moreover, the iron spans were no more functional than were wood spans for use as highway bridges. This fact would severely limit the value placed on the now surplus spans by potential purchasers. | 43 |
| The first two spans removed, those located on the western end of the approach, were each sold for $750 in November 1887 to E. A. Spaulding, a bridge builder who had done some work filling the Dubuque sloughs. Credit for the first span was not entered into the bridge company accounts until July 1888 and not until January 1889 for the second span. Spaulding did not pay cash but, instead, took the spans as credits against the work that he had performed for the bridge company. The use to which these spans were put is unknown.24 | 44 |
| The two spans located on the eastern end of the approach were also sold for $750 each in October 1889 to E. E. Firth, another contractor who worked on filling the sloughs. Inventory and appraisal sheets for the Iowa Department of Transportation indicate that two of the Dubuque approach spans were purchased about 1890 and adapted for use as wagon bridges on Dubuque county roads. These spans were possibly the same ones sold by the bridge company to Firth, who subsequently resold them to the county.25 | 45 |
| One of these spans, now known as the White Water Creek Bridge, was used on a minor county road about 4 miles west of Bernard, Iowa, until June 1999 (see Figure 9). This span, now owned by the Dubuque County Conservation Board, has been taken out of service and moved to a spot adjacent to the road. The Conservation Board also owns the other span, known in the years following its sale by the bridge company as both the Cloie Branch Bridge and the Little Maquoketa River Bridge. Since about 1993, it remains in the weeds next to a heritage trail just off Highway 52 at Clay Hill Road, approximately 6 miles northwest of Dubuque (see Figure 10). | 46 |
| Figure 9. White Water Creek Bridge, view from southwest, 1995. Photo from HABS/HAER Collection, HAER Iowa-31, Prints and Photographs Division, Library of Congress, Washington, DC. | |
| Figure 10. Cloie Branch Bridge, looking east. Photo by Makela Mangrich, 2001. | |
| In December 1892, the Dunleith and Dubuque Bridge Company sold another two of the approach spans to the Illinois Central Railroad at $600 each for reuse at an unknown location, leaving one span unsold and in storage. At some point about 1894, the Illinois Central Railroad purchased the last approach span, for an unknown amount, and erected it over the tracks of the Yazoo and Mississippi Valley Railroad (a subsidiary of the Illinois Central) at the Fairground Street crossing in Vicksburg, Mississippi. This wagon and pedestrian bridge was constructed as part of an agreement between the railroad and the City of Vicksburg, intended to ensure safe access to the Vicksburg fairground.26 | 47 |
| Completed in May 1895, the Fair Ground Street Bridge (the bridge is identified by the name it was originally given, which differs from the current name of the street it serves) still exists and consists of two spans: the former approach span of the Dubuque bridge, altered from an original length of approximately 93 feet to 81 feet, 93¼4 inches by removal of one panel; and a Keystone Bridge Company span of similar design and construction that was altered from an original length of about 105 feet to 91 feet, 6 inches by removal of one panel (see Figure 11). The origin of the second span is unknown, but, like the Dubuque span, it was certainly moved to its current site after having first been used as a railroad bridge.27 | 48 |
| Figure 11. Fair Ground Street Bridge, looking south, date unknown. Photo from HABS/HAER Collection, HAER Miss.-75, Prints and Photographs Division, Library of Congress, Washington, DC. | |
| The Fair Ground Street Bridge, as originally constructed, consisted of the two altered iron spans resting on concrete end piers and a steel center pier on a concrete base, and wood approach spans of heart cypress (see Figure 12). The floor system was constructed with steel floor beams, lateral and portal struts, and new, specially fabricated cast-iron shoes located above the center pier that joined the inclined end posts of the two spans at the middle of the bridge (see Figures 13 and 14). | 49 |
| Figure 12. Detail of middle connecting pier, Fair Ground Street Bridge, date unknown. Photo from HABS/HAER Collection, HAER Miss.-75, Prints and Photographs Division, Library of Congress, Washington, DC. | |
| Figure 13. Half section and half elevation detail of connecting cast-iron shoe at center pier for the Fair Ground Street Bridge, date unknown. Taken from drawings in the archives of the Kansas City Southern Railroad, Jackson, Mississippi. | |
| Figure 14. Section “E-F” detail of connecting cast-iron shoe at center pier for the Fair Ground Street Bridge, date unknown. Taken from drawings in the archives of the Kansas City Southern Railroad, Jackson, Mississippi. | |
| Early in October 1894, Yazoo and Mississippi Railroad Company Chief Engineer J. F. Wallace provided Second Vice President J. T. Harahan with an estimate of $12,500 to construct the Fair Ground Street Bridge.28 Presumably, this estimate would include the cost of the two iron spans, since the Illinois Central Railroad would certainly charge its subsidiary for the structures. Most of the cost of the bridge, however, would have been incurred in labor and new materials. The old spans would have likely been worth less than the $600 paid by the Illinois Central Railroad for each of the two Dubuque approach spans purchased in 1892. | 50 |
| The prices paid by various purchasers of surplus Dubuque approach spans, from the first sold in November 1874 to the two sold in December 1894, provide some indication of how the value of iron spans changed over a relatively short period of about two decades. The very precise sum of $2,686.30 paid by the CB&Q; Railroad for the “eighth” span sold in 1874 reflects the market value of an iron span at a time when wood was still used but was increasingly falling out of favor as a material for railroad bridges approaching 100 feet in length. Steel, on the other hand, was still very expensive and unpopular for use in railroad bridges of any length. In 1887 and 1889, just about the time that fabricators were beginning to make steel structural members available for use in spans of varying lengths, the value of the surplus iron Dubuque approach spans had dropped to $750. As bridge engineer and historian J. A. L. Waddell observed in 1916, when speaking of steel as a material for railroad bridges, by “1890 all the usual structural shapes could be procured at the same prices as for Wrought iron; and by 1895 its adoption for bridges was practically universal, and the production of wrought iron in large quantities was a thing of the past.”29 | 51 |
| By 1892, the value of the two Dubuque approach spans sold to the Illinois Central Railroad had been reduced to just $600. By 1894, the Yazoo and Mississippi Valley Railroad probably could have purchased new steel spans specifically fabricated to the length desired for use on the Fair Ground Street Bridge. It would have made sense to alter and reuse the old iron spans only if they could be acquired for a few hundred dollars each—a cost significantly less than that for newly fabricated steel spans. | 52 |
| The continued usefulness of the Dubuque Bridge approach spans is evidenced by the fact that the Cloie Branch Bridge and the Fair Ground Street Bridge continued to carry vehicular traffic until about 1993, and the White Water Creek Bridge did so until about 1999, albeit with restricted load limits. All three spans still exist because they held value and utility for more than a century beyond their original fabrication date, not as sources of scrap metal but as functional spans. | 53 |
| Because the Keystone Bridge Company was almost exclusively a builder of railroad bridges, the successful, adaptive reuse of the Dubuque bridge approach spans as highway bridges is particularly important. Almost all the 19th-century railroad bridges built by Keystone and similar companies have been destroyed. The Dubuque spans, along with five or so iron Keystone bridges that exist in other parts of the country (only four of which feature the Keystone column), are the last remaining works of a company that played a starring role in the drama of America’s industrial development during the latter half of the 19th century.30 Until it and approximately 27 other bridge firms were consolidated as the American Bridge Company in 1900, Keystone could be counted as one of the most important transportation-related industrial companies of its era. Its list of accomplishments included construction of bridges across the major western rivers that set records for length and load-carrying capacity, fabrication of structural members of the Brooklyn Bridge and the Statue of Liberty, development of special tools and fabrication machinery that advanced industrial practice, and methodologies for the testing of structural components that made bridges safer and more cost effective. | 54 |
| Together with the Eads Bridge in St. Louis, the Dubuque spans also represent the last remaining artifacts of an epic race between competing railroad interests to bridge the Mississippi and Missouri rivers on the way west. Resting in retirement as they now do in Dubuque County, Iowa, and Vicksburg, Mississippi, they serve as mute testaments to an earlier time when the trans-Mississippi West was largely undeveloped, and the fate of the country, still recovering from a bitter Civil War, was yet to be determined. | 55 |
Notes1. United States Congress, Annual Report of the Chief of Engineers to the Secretary of War. Appendix X, report prepared by G. K. Warren, 45th Cong., 3rd Session, pt. 2, vol. II., 1878:1029–33.2. Andrew Carnegie, Autobiography of Andrew Carnegie (Cambridge, Mass.: Riverside Press, 1920), 125.3. Carnegie, Autobiography, 123 (see n. 2).4. Carnegie, Autobiography, 124 (see n. 2).5. Mark Aldrich, “Engineering Success and Disaster: American Railroad Bridges, 1840–1900,” Railroad History 180 (Spring 1999):31–72.6. Carnegie, Autobiography, 124 (see n. 2).7. Andrew Carnegie, Pittsburgh, to the President and Directors of the Keystone Bridge Co., 25 January 1868, Union Iron Mills Letter Book, 1866–69, Carnegie Papers, United States Steel Corporation Archives, Boyer Pennsylvania. Since the initial research for this article was conducted, the Carnegie Papers have been transferred to the Western Pennsylvania Historical Society in Pittsburgh, Pennsylvania.8. Carnegie, Autobiography, 124 (see n. 2).9. ibid.10. Keystone Bridge Company, Descriptive Catalogue of Wrought-Iron Bridges (Philadelphia: Allen, Lance & Scott, 1875), 18–21.11.Asher & Adams’ Pictorial Album of American Industry, 1876 (New York: Rutledge Books, 1976), 87; Biographical Sketches of the Leading Men of Chicago (Chicago: Wilson & St. Clair, 1876), 40–42.12.Engineering 6 (February 1880):103.13. For more on the competition between Carnegie and Boomer, see Robert W. Jackson, Rails across the Mississippi: A History of the St. Louis Bridge (Urbana, Ill.: Univ. of Illinois Press, 2001).14. Information in this article concerning the specifications and cost of the Dunleith and Dubuque Bridge is taken from the Dunleith and Dubuque Bridge Company records in the Illinois Central Railroad Collection, Newberry Library, Chicago, Illinois [hereafter D&D; records].15. J. H. Linville and J. L. Piper, Improvement in Iron Truss-Bridges, U.S. Patent No. 34,183, issued 14 January 1862, United States Patent Office, Washington, DC; J. H. Linville and J. L. Piper, Improvement in Wrought-Iron Bridges, U.S. Patent No. 50,723, issued 31 October 1865, United States Patent Office, Washington, DC.16. Charles C. Schneider, “The Evolution of the Practice of American Bridge Building,” Transactions of the American Society of Civil Engineers 54 (1905): 217.17. Keystone Bridge Company, Descriptive Catalogue, 25 (see n. 10).18. Samuel J. Reeves, Construction of Wrought-Iron Shafts or Columns, U.S. Patent No. 35,582, issued 17 June 1862, United States Patent Office, Washington, DC.19. Keystone Bridge Company, Descriptive Catalogue, 25 (see n. 10).20. C. H. Booth, Secretary of the Dunleith & Dubuque Bridge Company, to Col. Roswell B. Mason, Chief Engineer, Dunleith & Dubuque Bridge Company, 22 December 1874, D&D; records (see n. 14).21.Dubuque Daily Times (17 January 1872); Dubuque Herald (17 January 1872).22. Geo. S. Morison, Plattsmouth, Nebraska, to Hon. W. B. Allison, Esq., Washington, DC, 23 March 1880, original handwritten manuscript, D&D; records (see n. 14).23. Geo. S. Morison, Plattsmouth, Nebraska, to Hon. W. B. Allison, Esq., President of the Dunseith & Dubuque Bridge Co., Dubuque, Iowa, 18 June 1880, original handwritten manuscript, D&D; records (see n. 14).24. Information in this article concerning the disposition of the approach spans of the Dunleith & Dubuque Bridge is taken from the D&D; records (see n. 14).25. These sheets may be found in the office of the Dubuque County Engineer, Dubuque, Iowa.26. City of Vicksburg Minute Book F (November 19, 1888 to May 21, 1894), 9 March 1893, 574–75; City of Vicksburg Minute Book G (June 4, 1894 to April 18, 1898), 29 August 1894, 54–55. These records were obtained and made available to the author by Don Banks, PhD, PE, of Vicksburg, Mississippi. See also, Vicksburg Evening Post (10 March 1893), (11 May 1895), (16 May 1895), and (21 May 1895).27. Information regarding construction details of the Fair Ground Street Bridge is taken from copies of original construction drawings dating from 13 November 1894 to 20 December 1894 that are located in the Jackson, Mississippi, office of the Kansas City Southern Railroad. These records were obtained and made available to the author by Don Banks, PhD, PE, of Vicksburg, Mississippi.28. J. F. Wallace, Chief Engineer, to Mr. J. T. Harahan, Second Vice President, Chicago, 4 October 1894, Illinois Central Railroad Collection, Box 51, Newberry Library, Chicago, Illinois.29. J. A. L. Waddell, Bridge Engineering, vol. 1 (New York: John Wiley & Sons, 1916), 28.30. The other surviving iron Keystone bridges known to the author are as follows: Kessler Bridge (c. 1870), McGraw Park, Bailey, Colo. (with Keystone column); Stewartstown Railroad Bridge (1870), Stewartstown Railroad over Valley Road, Stewartstown, Penn. (with Keystone column); Riverside Avenue Bridge (1871), Riverside Avenue over Northeast Corridor, Greenwich, Conn.; Pine Creek Park (Mill Hill Road) Bridge (1872), Pine Creek Road over Pine Creek, Fairfield, Conn. (with Keystone column); Windsor Harbor Road Bridge (1874), Windsor Harbor Road over Rock Creek, Kimmswick, Mo. (with Keystone column). | |
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