Cairo Railroad Bridge

Cairo Bridge (Illinois Central Railroad)

The Cairo Bridge, constructed by the Illinois Central Railroad, currently carries the Canadian National Railway between Cairo, Illinois and Kentucky. It was the first railroad link completed between Chicago and New Orleans and revolutionized rail travel along the Mississippi River.


History

Located at the junction of the Mississippi and Ohio Rivers, Cairo, Illinois prospered as a steamboat port. The Illinois Central Railroad (IC), chartered by the Illinois General Assembly in 1851, was completed between Galena and Cairo in 1856, connecting major agricultural and industrial centers, including Chicago. 3 4 5 At the time of its completion, the IC was the longest single railroad operating in the United States at 700 miles in length.

The need for a railroad bridge crossing over the Ohio River between Cairo, Illinois, and Kentucky was desperate by the late 1800s. 1 As many as 500,000 railroad cars were being ferried across the Ohio and Mississippi Rivers each year, and by 1886, shipments via the river and railroad were valued at $60 million, the highest per capita in the nation. 2

Early discussions for a bridge across the Ohio River began in January 1859 after the IC expressed desires for connections to Mobile, Alabama, and New Orleans via a proposed “Lakes-to-Gulf” route. 3 6 he growing importance of trade along the Gulf was a major factor in the initial push. 7 A lack of crossing of the Ohio River, aptly named the “Great River” by the Seneca Indians, proved to be a formidable obstacle as the river and floodplain were very wide. 3 8

During this time, the Mississippi and Ohio Railroad (M&O) extended its line north to Columbus, Kentucky, just shy of Cairo. A temporary connection between the M&O and the IC was made via a steamboat ferry along the Mississippi River, but just days after the connection was made, Fort Sumpter was attacked and delayed any further work between the two companies. 3 In 1870, during the midst of Reconstruction, the IC attempted to persuade the M&O to extend its railroad north towards Wickliffe, Kentucky. The IC offered the cash-strapped M&O funding for the extension but after no action was undertaken by the M&O, the IC began to seek another route to the south. 3 9

In 1872, the IC negotiated with the Southern Railroad Association to extend the Mississippi Central (MC), which later became the Chicago, St. Louis & New Orleans Railroad (CSL&NO) in 1878, to Wickliffe, opposite of Cairo. Both the IC and MC felt that there was no immediate need for a bridge over the Ohio River as the IC used standard gauge and MC preferred a five-foot gauge, and that much expense would need to be undertaken to convert MC’s gauge. To transfer goods across the river, the IC commissioned the H.S. McComb, a steam transfer ferry, on December 24, 1873, which could carry six passenger or twelve freight cars. A slightly smaller steamer, the ten-car W.H. Osborne, was later added to the fleet. 3 10 11

(In July 1881, the CSL&NO converted their entire 550-mile railroad from a five-foot gauge to standard gauge, a process that took less than one day but required 3,000 laborers. 16)

Traffic demands soon began to overwhelm the ferry and the IC began exploring options for the construction of a fixed crossing over the Ohio. Steamboat operators saw the move as an attack on their industry, claiming that bridge piers would be a hazard to river navigation and a low vertical clearance would hinder their vessels. 12 13

The passage of the Ohio River Bridges Act in 1872, heralded as a victory by steamboat operators, required that bridges feature 40 to 45-feet minimum high-water clearance heights, 350-feet channel span widths, and pivot spans for tall-stacked boats. 3 14 The Act also specified that any railroad or bridge company had to notify the Secretary of War of its intentions and to present documentation on the bridge’s design. The Secretary then had to appoint a board to review the plans, and upon their approval, enter into a contract with the proposing company. 14

The restrictions were unique to the Ohio, as other river crossings, such as the Missouri and Mississippi, were granted charters individually by Congress with design guidelines enforced on a policy level by the War Department. 14 A black market for bridge charters developed, with one Mississippi River bridge charter fetching $250,000. An amendment to the Ohio River Bridges Act in 1883 allowed for the removal of the pivot span if a 53-foot high-water clearance was provided. 30

Bridge Proposals

The first major push for a bridge over the Ohio River after the Civil War had concluded was by IC President W.K. Ackerman in 1870 who had ordered preliminary surveys be made of a river crossing. 16 Officials at the IC and the CSL&NO spent the next few years surveying for a bridge site. Another proposal, from Judge Lawrence Trimble of Paducah, Kentucky, president of the New Orleans & Ohio Railroad (NO&O), called for a crossing at Paducah to connect the IC with the NO&O. That idea was not well received by the IC as it did not connect to Cairo. 15

By 1884, the IC was transferring 52,000 freight cars and 8,000 passenger cars a year at Cairo by steamboat; a fixed crossing was desperately needed. 16

On March 17, 1886, the Commonwealth of Kentucky authorized both the IC and the CSL&NO to build a bridge over the Ohio River at Cairo. 17 An amendment by the legislature, at the request of the NO&O, provided for a bridge at either Cairo or at any point within five miles of the city limits of Paducah.

Edward T. Jeffrey, general manager of the IC, was named general manager of the CSL&NO to supervise the bridge construction. 19 Jeffrey then asked Morison and E.L. Corthell to review a bridge design proposal prepared by another engineer, and Morison and Corthell issued a joint report in February 1887 that made general comments about the superstructure and substructure but noted that a site inspection was needed.

On March 11, Morrison, Corthell, Jeffery, and George Field of the Union Bridge Company met at the proposed bridge site during a spring flood of the Ohio River, which allowed them to witness the impact of the waters on the topography and helped formulate early bridge design guidelines. 19 Borings were made about 200 feet beneath the river which revealed that it composed of sand and gravel. Morison and Corthell recommended that hybrid piers be designed and constructed with pneumatic caissons to provide additional stability with a foundation of timber crib-work filled with concrete. 20

The proposed site featured a river width of 4,000 feet, but just two miles upriver, the width narrowed to around 3,000 feet, which raised the possibility of filling in some of the river with stone to narrow the channel. 20 The idea was rejected, which led Morison and Corthell to design a 52 truss steel span bridge with a length of 10,560 feet, the longest of any metal bridge in the world. 21 22 The total length, including 9,901-feet of timber trestles, 39 was 20,461-feet (3.875 miles). 21 22

The channel crossing would consist of nine pin-connected, Whipple through trusses, two of which would be 518.5-feet long, and the other seven 400-feet long, and three 249-feet Pratt deck truss spans. 21 22 The extremely long truss spans had been proposed for other sites previously, but conservative railroad clients had nixed all of those ideas until now. It would be complemented with 21 150-foot-long deck spans and one 106-foot deck span for the Kentucky approach and 17 150-foot-long deck spans and one 106-foot deck span for the Illinois approach. 28

The crossing would be far heavier than any bridge that Morison had engineered, with the main 12 spans weighing 13.5 million pounds and the approaches weighing 7.8-million pounds. 25 26 Counting for the superstructure and substructure, but not the approaches, the Cairo span weighed 194.6-million pounds. 25 26 For comparison, the Nebraska City Bridge superstructure that Morrison had also designed weighed a measly three-million pounds.23 24

Each of the channel spans would be supported with Bedford, Indiana-sourced limestone masonry piers 29 that would weigh up to 9,400 tons, while the approaches would be supported by cylinder piers filled with concrete. 27 The substructures for the channel spans would consist of ten massive masonry piers founded on 75-foot-deep pneumatic caissons, making for a total height of the bridge 250 feet. 29

Construction

The contract with the War Department stipulated that work on the Cairo crossing be started before March 29, 1887. 14 20 Pile driving for the Kentucky approach had already commenced when Morison began preparing construction plans for the main spans. A contract for construction was awarded to the Union Bridge Company in May. 31

On July 1, 1887, workers began framing for the first caisson for Pier 11 on land in Cairo, and by mid-August, they had launched the completed caisson into the Ohio River and maneuvered it into position, where it was pressurized and sunk to the river bottom. A pumping crew operated pneumatic equipment from a barge over the caisson and sand hogs in the pressurized chamber began excavating through the bed of the river at a rate of four inches per day. The crew completed the timber crib on the caisson roof on October 6 and the laying of granite and limestone blocks began on October 11. 32 The caisson floor reached nearly 75-feet below the low water mark of the Ohio by November 10.

There were issues of caisson fever because of the air pressure that approached 35 PSI at such depths, and some workers were temporarily paralyzed and two were killed as a result. 33 34 Hot coffee, warm baths, and the pumping of cool air down into the chambers seemed to solve the caisson fever issues at first, although five other workers later died.

Masons set the lat stone on the coping of Pier 8 on February 19, 1889, completing the construction of the piers for the Cairo bridge. 35

Steelworkers from Baird Brothers began constructing the superstructure in July 1888, taking in prefabricated truss components that were shipped via the railroad from the Union Bridge Company in Pennsylvania. 27 A team of 12 handled the steel incoming from the train, who then directed it to a derrick that lifted the components to a ten-ton push cart. A second 12 person crew pushed the material to a large timber traveler where a team of 25 would then assemble each channel span, with eight on top of the scaffold of the traveler, two at the ropes, two at the engine, and one engineer who supervised. It took six days to complete one span at which point the falsework would be removed and used again for the next span to be erected.

The first train, which consisted of nine 2-6-0 Mogul locomotives that weighed 75 tons each, crossed the new Cairo Bridge from Illinois into Kentucky at 9 AM on October 29, 1889. 36 38 They were the heaviest engines in service by the IC. Engineer Gordon Weldon was on hand, along with IC President Stuyvesant Fish and Vice President E.H. Harriman. In the engine prior was engineer M. Eagan, IC General Manager C.A. Beck, and General Superintendent A.W. Sullivan.  The 675-ton train inched across the Cairo Bridge and when the last engine passed the easternmost truss, thousands who had gathered in Cairo to watch the spectacle broke out into cheers.

The first train then backed over the bridge and picked up a tenth Mogul engine and sped across the bridge at full speed, followed by a second train full of newspapermen. 36 38 A southbound freight followed right after, which inaugurated regular service over the crossing.

Minor work continued on the crossing until March 1, 1890. 59 Ultimately, the Cairo Bridge cost $2,675,457.92, or $200,000 over the original estimate. 37 Broken down, it included: 59

  • Substructure: $1,189,743.73
  • Superstructure: $765,616.14
  • Illinois approach: $338,267.40
  • Kentucky approach: $290,190.51
  • Protection works: $8,622.87
  • Service tracks: $565.90
  • Right-of-way/franchises: $12,277.63
  • Engineering: $67,620.65
  • Legal/supervisory: $947.24
  • Miscellaneous: $1,605.85

The bridge was just slightly more than $200,000 over the original estimate.37

Improvements included the replacement of the 9,901-foot timber trestle with fill in 1891 39 and the repair of a cracked pier on the bridge because of a 6.6 magnitude earthquake on October 31, 1895. 2 The floor system of the truss spans were reinforced in 1914 and the floor system of the approaches was replaced in 1934-35. 38

Replacement

In 1921, facing congestion and weight limits with its aging single-track bridge over the Ohio River, the IC submitted plans to the War Department for the replacement of the Cairo Bridge with a double-track superstructure that would reuse the existing piers. 38 Opposition to that plan nixed the double-track proposal and in 1932, the IC completed a supplementary freight line between Edgewood and Reevesville that connected to an existing IC line at St. Louis and Fulton, Kentucky that utilized a railroad bridge between Metropolis, Illinois, and Paducah.

On May 25, 1946, the IC requested Modjeski & Masters to complete a study of the current condition of the Cairo Bridge. 38 It stated that reinforcements to the bridge in 1914 and in the 1930s increased the dead load carried by the spans and that a number of connecting pins on the trusses had been overtaxed. The distribution of stresses was hammered along the bars of the end hanger members. In one instance, one bar carried 97% of the total live load stress due to the pin wear of an outer eye-bar. The expansion rollers had also been worn to an elliptical shape, and the shoes had developed pockets into which the rollers fitted that resisted expansion movements which resulted in the formation of cracks in the stone masonry of the piers that required steel banding. Additionally, the Whipple trusses under live loads were over-stressing the bottom chords by 30% and 45%, and that there were varying amounts of over-stresses in the top chords, end posts, and bottom laterals under high wind.

The report recommended that the live loads and speeds not increase on the Cairo Bridge, and that the existing crossing be replaced as it had reached the end of its useful life. 38 To keep the bridge in service, an anemometer was installed so that when high winds were reported, trains would be prohibited from the bridge.

Plans to replace the bridge began in July 1947 under Modjeski & Masters. 38 Early studies focused on constructing a bridge 150-feet upstream from the existing bridge and using some of the existing approaches, given that there were concerns with high water and drift hazards that a temporary bridge could encounter during the reconstruction process. Consideration was given to a channel span of 648-feet, the same as the Louisville & Nashville (L&N) Bridge at Henderson, Kentucky, but to give a good arrangement of trusses on the new bridge, the channel span length was increased to 688-feet with navigation clearance of 668-feet, or 20-feet more than the Henderson crossing.

After consideration from the Army Corps of Engineers, a revised plan was developed for a new Cairo Bridge 150-feet upstream with the main channel closer to the Illinois shore, which would include a 721-foot cantilever span. 38 Piers 5 through 9 would remain in place, with piers C through G being replaced. On the Kentucky approach, 255-foot deck spans would be constructed to replace the three existing through spans. A formal report was submitted to the War Department for approval in July 1947.

Opposition developed among riverboat interests who called for a larger navigational clearance. 38 In comparison, the Metropolis Bridge used by the IC provided a 700-foot clearance and the adjoining Cairo Highway Bridge featured an 800-foot clearance. To remedy the issue, the IC submitted a proposal to reconstruct the existing Cairo Bridge on the existing alignment, which was approved by the Chief of Engineers and the Assistant Secretary of the Army on July 6, 1948. It included the condition that at least two of the four spans on the Illinois shore be kept free of falsework at all times.

Replacement Design

In early 1948, Modjeski & Masters began to prepare plans for the reconstruction of the Cairo Bridge, which was to incorporate all riveted through truss spans of the same lengths as the original bridges with the exception of three 405-foot through trusses on the Kentucky approach that would be replaced with six 200-foot deck trusses. 38 Specifically, the superstructure would consist of two 518-foot and four 400-foot Warren through truss spans and six 198-foot deck truss spans. 39

The trusses would utilize carbon steel with the exception of the chords and some diagonals where silicon steel proved to be more economical. 39 To guard against brine drip, all bottom laterals, top cover plates of stringers and floor beams, plates, and top angles of the stringer cross frames of the through spans called for copper-bearing steel. All truss bearings were to be on 10-inch diameter stainless steel rollers geared to similar alloy metal roller plates.

Because of the poor conditions of some piers, a two-foot-thick concrete jacket would be needed around Piers 6, 8, and 10. 38 39

Because of the high cost of detouring all freight to the Metropolis Bridge, the bidding contractors for construction were required to state as an item of their bid the number of hours of detour time which was evaluated at one-half the estimated cost of detouring trains. An equal penalty was provided for exceeding the time in the bid. 38

A contract to conduct 15 soil borings were awarded to Sprague & Henwood, Inc. on June 11. 40 The first hole was drilled just four days later and the work was completed on October 8.

An investigation of the masonry piers began on September 7, 1948, when a contract was awarded to the Pennsylvania Drilling Company. 40 The company conducted core drilling on Piers 6, 8, and 10 to examine the stone and mortar between September 17 and October 20. Drilling began on September 17 at Pier VIII and was completed on October 20 at Pier X. The results showed that the core of the piers was solid and in excellent condition, and a followup visual inspection indicated an excellent bond between the stone and mortar.

Substructure Construction

Substructure Contract No. 1 involved the encasement of Piers 6, 8, and 10 with reinforced concrete anchored to the existing stone and supported on tremie seal supplemental footings atop steel bearing piles, the cutting of recesses in Piers 2 through 5 for the bearings of the new deck truss spans, and the construction of three new reinforced concrete piers at the midpoints of each of the through spans between Piers 2 and 5 for the new deck trusses. 40 Bids for Substructure Contract No. 1 were received on May 4, 1949, and on May 21, the contract was awarded to the Kansas City Bridge Company and the Massman Construction Company who had bid jointly. The contractor began shipping in equipment in early June and construction began on July 19. The contract required that the work be completed for the superstructure construction within one year and that all work on the pier be finished 150 days after that.

The first concrete pour for Substructure Contract No. 1 was made at Pier C on November 2, which involved batching three mixer trucks at a ready-mix plant near the north end of the bridge, hauling the trucks to the top of the levee where the contents would be dumped into a hopper and transported via one-cubic-yard buckets on a pontoon across the river via a tugboat. 40 The concrete would then be transferred via a pumpcrete machine by crane. The process was tedious and slow, and only 10.5 cubic yards of concrete were poured per hour.

To expedite the process, a narrow three-foot gauge railroad was built from the Kentucky bank to Pier C in 1950 which employed one engine and two flat cars. 40 A six cubic yard hopper was set up over the railroad so that the concrete could be dumped by gravity into three one cubic yard buckets that were discharged into forms by a crawler crane. Up to 30 cubic yards of concrete were poured per hour using this method.

Other work included:

  • The excavation around Pier 10 for pier encasement began August 16, 1949. 40 Expansion anchors were drilled and placed in the pier from top-down to the water line, followed by the driving of steel bearing piles for the new reinforced concrete jacket. Work was slowed because of flooding and the project was finished on October 5, 1950.
  • The encasement of Pier 6 began on July 19, 1949, and was finished on January 17, 1951.
  • The encasement of Pier 8 began on October 6, 1949, and was completed on February 21, 1951.
  • Construction of a new caisson pier, midway between existing Piers 4 and 5, began on October 13, 1949, and was completed on March 23, 1951.
  • Work on Pier B, between Piers 3 and 4, began on September 21, 1949, and was finished on March 22, 1951.
  • The excavation for Pier C, located between Piers 2 and 3, began on September 13, 1949, and was completed on March 22, 1951.
  • The completion of the recesses in Piers 2 and 5 was hampered by high water and the small size of the openings, although it was completed on March 21, 1951.

Substructure Contract No. 1 was completed on June 28, 1951, with the exception of the installation of heavy riprap around Piers 6, 8, and 10. 38 Instead, the riprap was installed during favorable river stages and was completed in August 1952.

Superstructure Construction

Superstructure Contract No. 2 involved the replacement of nine through trusses, six Warren through trusses, and six deck trusses. 40 The contract specified that the bridge would continue to operate through the reconstruction of the superstructure, with a bonus and penalty of $200 per hour for time either saved or lost compared with a total number of hours of anticipated detour time that each contractor would provide. Bids for the superstructure were received on September 1, 1949, and the American Bridge Company was awarded the contract with a detour time of 292 hours listed in their proposal.

The contract specified that the company was limited to the erection of the spans on falsework adjacent to their final position, which would then be rolled into place. 40 To facilitate quicker construction, two of the 200-foot deck truss spans for the Kentucky approach were adapted to provide falsework for the river spans. The trusses were slightly strengthened and a few members were added to extend the spans for full-length falsework. Two short spans were supported at each pier by a steel bent resting partly on the pier and partly on a steel pile foundation, and at midpoint by a common steel bent supported by a steel pile foundation. They could then be moved by picking up the components and moving them via a barge.

Due to the complexities of the requirements as to the maintenance of river and rail traffic, the contractors developed a scheme of erecting the new truss and the disposal of the old span, which involved the erection of a span on falsework complete with track, the rolling out the old span onto falsework upstream of the bridge, the rolling in the new span, and the launching of the old span into the river. 40 It was a method that was far cheaper than dismantling the span component by component.

The company began assembling crews and equipment on April 24, 1950, and preliminary work involved the construction of a field office and the preparation of barges for derricks and for mounting structural towers for moving falsework spans. 40 Falsework bents were built for Span 10, and two falsework deck spans were completed. Preparations for other erection work were finished on September 2.

  • Span 10 was launched on November 9, 1950, and the span was opened to navigation on June 11, 1951. The salvage of the old span was delayed by high water.
  • Span 9 was launched on June 27, 1951, and the span was opened to navigation on August 11.
  • Span 8 was launched on August 21 and the span was opened to navigation on September 15.
  • Span 7 was launched on September 27 and the span was opened to navigation on October 16.
  • Span 6 was launched on November 1 and the span was opened to navigation on March 24, 1952.
  • Span 5 was launched on December 31, and the span was opened to navigation on March 24, 1952.

Contract No. 2 work was completed in May 1952 38 with only 119 hours and 45 minutes of detour time, much shorter than the 292 hours that the company had requested. 40 The shortened time was attributed to the launching of the trusses into the river.


Gallery


Information

  • State: Illinois, Kentucky
  • Route: Canadian National Railway
  • Type: Warren Through Truss
  • Status: Active - Railroad
  • Total Length: 20,461 feet (1889); 10,580 feet (1949)
  • Main Span Length: 518.5 feet (1889); 518.11 feet (1952)
  • Deck Width: 22-25 feet (1952)

Sources

  1. Bass, Kyle. “Cairo, Illinois.” Illinois History: A Magazine for Young People Apr. 2001: 48-49.Illinois Periodicals Online. Web. 7 Feb. 2012. Article.
  2. “First Half Century.” The Cairo Project. Southern Illinois University Carbondale School of Journalism, n.d. Web. 9 Feb. 2012. Article.
  3. United States. Dept. of Interior National Park Service. “Cairo Bridge (HAER No. IL-36).” Nebraska City Bridge. By Clayton B. Fraser. Denver: Historic American Engineering Record, 1986. 221-261.Print.
  4. Overton, Richard C. Burlington Route. New York: Alfred A. Knopf, 1965. 12. Print.
  5. Holbrook, Stewart H. The Story of American Railroads. New York: Crown Publishers, 1947. 103-104.Print.
  6. Fish, Stuyvesant, President. Report to the Board of Directors of the Chicago, St. Louis and New Orleans Railroad Company. 24 Feb. 1892. N. pag. Print. (Newberry Library, Illinois Central Collection)
  7. Stover, John F. History of the Illinois Central Railroad. New York: Macmillan Publishing Co, 1975. 144. Print.
  8. Howard, Robert West. “The Ohio River: Throughway ‘For the West’.” Water Trails West. New York: Doubleday & Company, 1978. 44. Print.
  9. Balcom, S.F., Assistant Engineer, Illinois Central Railroad.The Ohio River Bridge at Cairo. 1 June 1988. N. pag. Print. (Paper presented to Illinois Society of Civil Engineers and Surveyors, excerpted in Railroad Gazette.)
  10. Corliss, Carton J. Main Line of Mid-America. New York: Creative Age Press, 1950. 205-206. Print.
  11. Stover, John F. History of the Illinois Central Railroad. New York: Macmillan Publishing Co, 1975. 159. Print.
  12. Heney, Lewis H. A Congressional History of Railways in the United States: 1850-1887. New York: Augustus Kelly, 1968 (reprint, orig. 1908-1910). 231-232. Print.
  13. Plowden, David. Bridges: The Spans of North America. Norton, 2001. 75-78. Print.
  14. “An Act to Authorize the Construction of Bridges Across the Ohio River, and to Prescribe the Dimensions of the Same.” 17 Dec. 1872. “A General Bill for Western Rivers.”Engineering News, 11 Feb. 1888. Print.
  15. Corliss, Carlton Jonathan. Main Line of Mid-America. Creative Age Press, 1950. 229-231. Print.
  16. Fish, Stuyvesant. “Report to the Board of Directors.” From: Stover, John F. History of the Illinois Central Railroad. New York: Macmillan Publishing Co, 1975. 202. Print.
  17. “An Act Authorizing the Chicago, St. Louis and New Orleans Railroad Company and the Illinois Central Railroad Company, or Either of Them Separately, to Build and Maintain a Railroad Bridge across the Ohio River.” Commonwealth of Kentucky, 30 Mar. 1866. Reprinted in: Morison, George S. The Cairo Bridge. Chicago: Knight, Leonard and Co., 1892. 20. Print.
  18. Corliss. 229-231.
  19. Fish. 9.
  20. Morison, George S. and E.L. Corthell. “Report to E.T. Jeffery.” 3 Mar. 1877.  Reprinted in: Morison, George S. The Cairo Bridge. Chicago: Knight, Leonard and Co., 1892. n. pag. Print.
  21. Morison, George S. The Cairo Bridge. 10. Print.
  22. “Final Report on the Reconstruction, Illinois Central Railroad, Cairo Bridge Over the Ohio River.” Harrisburg, PA: Modjeski and Masters, 1 June 1953. 15. Print.
  23. Morison, George S. The Plattsmouth Bridge. New York: S.B. Leverich, 1882. 10. Print.
  24. Morison, George S. The Nebraska City Bridge. Chicago: Knight, Lenoard and Co., 1892. 14. Print.
  25. Morison, George S. The Cairo Bridge. 12-13. Print.
  26. Corthell, E.L. ”Address on Retiring from Presidency of the Western Society of Engineers.” Read before the Western Society of Engineers, 8 Jan. 1890.
  27. “Fast Erecting on the Cairo Bridge.” Railroad Gazette 11 Jan. 1889. 18-19. Print.
  28. “The Cairo Bridge.” Railroad and Engineering Journal Dec. 1889. 557.
  29. Morison, George S. The Cairo Bridge. 10-11. Print.
  30. “Act of Congress Authorizing Construction of Bridges over the Ohio River.” 17 Dec. 1872. Reprinted: Morison, George S. The Cairo Bridge.
  31. “Contract for Bridge Across the Ohio River, at Cairo, Ills.” Reprinted: Morison, George S. The Cairo Bridge. 4 May 1887. Note: Contract between the Union Bridge Company and the Chicago, St. Louis and New Orleans Railroad Company.
  32. Morison, George S. The Cairo Bridge. 11. Print.
  33. Connor, Edward H. “The Substructure of the Cairo Bridge.” Presented to Engineers’ Club of St. Louis, 19 Feb. 1890. Reprinted: Journal of American Engineering Studies. June 1890. 296-297.
  34. Morison, George S. The Cairo Bridge. 11-12. Print.
  35. Morison, George S. The Cairo Bridge. 12. Print.
  36. Corliss. 226-228.
  37. Morison, George S. The Cairo Bridge. 14-16. Print.
  38. Modjeski and Masters. “General Narrative.” Final Report on Reconstruction Illinois Central Railroad Cairo Bridge Over the Ohio River. N.p.: n.p., 1953. 13-21. Print.
  39. Modjeski and Masters. “Design of Bridge.” 23-28.
  40. Modjeski and Masters. “Construction of Bridge.” 31-72.

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