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This Knight's Key Bridge is the longest single structure in the whole Key West
Extension, stretching seven miles across open sea. From one end of it the distant shore is barely visible. Due to the depth of the water, huge steel girders mounted on concrete piers were used. The bridge comprised 316 80-ft. spans, 19 60-ft. spans and 210 53-ft. concrete arches at the southern end where shallower water was found. The track itself lay 30 ft. above the low tide water mark. At the point where the lines ran across Moser Channel a swing bridge, approximately 250 ft. in length, was introduced to allow the passage of shipping.
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observing atmospheric conditions, noted an approaching disturbance, and the governmental observatory also gave him due warning. The builders, however, had received a false alarm in 1905 and did not take sufficient heed The storm swept mercilessly upon the workings. The gangers scurried to the frail shelter of their floating quarters on the barges. The houseboats were torn loose from their moorings ; some were driven out into the fury of the raging sea, while others were flung and shattered against the keys and reefs. Passing steamers rescued many survivors after days of exposure, but more than seventy men were lost.
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and set in place by floating derricks. The railway gangers completed their tasks in less than half the time taken by the contractors. On one occasion, six spans were placed in position within four hours, while on another the laborers erected a span in twenty minutes. The Bahia Honda bridge was built by means of temporary timber framework and an overhead travelling crane. The precautions taken to ensure the workers' safety were such that not a life was lost during the erection of the 32,900 ft. of steel that went to the building of Knight's Key and Bahia Honda bridges.
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Work began in the spring of 1909 and was completed in
January, 1912. The bridge was 35,815 feet in length, and consisted of 335 80-foot and 60-foot deck plate girder steel spans, rested on concrete piers, and a concrete viaduct, consisting of 210 53-foot arches and a drawbridge 253 feet in length. Altogether, the bridge rested upon 546 concrete foundation piers, far exceeding the number in any other railway bridge in the world. Each of the piers in the main structure rested on bedrock, in some cases as much as 28 feet below the water line.
247:, there was another strip of open sea, where depths of 30 ft. were encountered, and this presented an even greater obstacle than the Knight's Key section. Bahia Honda has a total length of just over a mile. Here Coe decided that another bridge had to be constructed, having 13 spans, each 128 ft. long, 13 spans of 186 ft., and one more of 247 ft. In addition there are nine arches of 80-foot span.
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towed up coffer-dams, huge steel cylinders, which were lowered over the dredged positions. Floating pile-drivers then drove steel-pointed piles into the coral rock until they were securely fixed. Through this method of working there was less risk of the piles slipping owing to shifting of rock, for the constructors were able to determine if the rock was solid or unstable and crumbling.
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especially the Seven Mile Bridge portion, for nothing like it had ever been attempted before—or has been since. Coe developed methods of construction to meet untried conditions, and those methods proved successful. Indeed, most of the Key West extension still withstand the imponderable forces of nature—wind, sea and tide.
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The railhead approached Knight's Key itself in
February, 1908. Operations then ceased temporarily while the builders considered how the seven miles of sea, varying from 18 to 22 ft. deep, should be overcome. Owing to the impossibility of dumping for an embankment, Coe decided to build a viaduct.
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was constructed from 1909 to 1912 under the direction of Coe as part of the
Florida East Coast Railway's Key West Extension, also known as the Overseas Railroad. The logistics of assembling labor and materials and overcoming the difficulties presented by deep water, normal tides and hurricanes attest
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In effect, owner and founder Flager’s money and Coe’s engineering genius provided private money and engineering expertise to pay for and design the public infrastructure that became U.S. Route 1. It is doubtful if the highway would ever have been laid out and built if the
Florida East Coast Railway
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began his railroad building in 1892. Under
Florida's generous land-grant laws passed in 1893, 8,000 acres (3,200 ha) could be claimed from the state for every mile (1.6 km) built. Flagler eventually claimed a total in excess of two million acres (8,000 km) for building the FEC, and
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Some remarkable figures give an idea of the vast amount of work involved in the construction of the Key West extension. The project from beginning to end meant the assembling of 38,000 tons of structural steel, 461,000 cubic yards of concrete ; the transport and distribution of 800,000 barrels
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Coe determined that the destructive force of the waves lay not in their impact against the bank, but in their retreat or undertow, which dragged away and undermined it. Experiment proved that a smooth surface, over which the heavy seas might glide and in their retreat find no hold, offered the best
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The longest and in some respects the most imposing of all structures on the Key West
Extension from an engineering standpoint was the Knights Key-Pigeon Key-Moser Channel-Pacet Channel Bridge, later commonly known as the Seven Mile Bridge. Three years were required to complete this huge structure.
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Despite the tropical storms and hurricanes which abound in this part of the world, the extension has successfully withstood the most violent attacks which the ruthless fury of nature can unloose. One of the worst hurricanes experienced beat down upon the works in 1906. Coe, who had been carefully
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When the work on bridges began beyond Knight's Key, Coe outsourced the setting of the steel to various contractors. As this method proved unsuccessful, the operations were put exclusively in the hands of Coe's own men. The deck girder spans were brought to the piers on barges, and were then lifted
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When the track passed over shallow water travelling excavators were utilized to form a solid embankment of debris. Pipe-lines were laid down in some places along the center of the permanent way, and the ballast pumped through these conduits was deposited where required, the water draining off. The
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One of the reasons
Flagler wanted to build the Key West Extension was at the time Key West was a major coaling station for ship traffic between South America and New York. Flagler thought it would be profitable for coal to be brought by railroad to Key West for coaling those ships. But by the time
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The building of Key West over land and sea under a torrid sun, across channels and surging waters, across bleak little islands, swept by fierce tropical storms, ranks as one of the greatest achievements in railway engineering. There were no precedents to follow in building the Key West
Extension,
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In 1909, another hurricane reached a velocity of 125 miles an hour. This time, warning instructions were observed and the barges towed into safety beforehand. Although miles of embankment were washed away no real damage was done to the concrete work. Five girders on Knight's Key Bridge were blown
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Coe had yet another problem in the adequate protection of the vast quantities of steelwork in the bridges from the effects of oxidization caused by exposure to salt water. The excessively moist air of
Florida also rusts metal within a short space of time. Experiments to discover the most suitable
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After the sinking of the piles, concrete was dumped upon the sea bed to a depth of 5 ft., forming the real basis for the piers. Molds were used for the shaping of the reinforced concrete arches and great precautions taken to obviate cracks set up by expansion. The rubble for the concrete was
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The prevalence of devastating hurricanes and heavy seas made it imperative that the structure be unusually strong. First, the positions of the piers were charted under Coe’s direction; then dredgers scooped the sand from the sea's bed, exposing the coral rock necessary for foundations. Next, tugs
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Despite the hardships, the final link of the Florida East Coast Railway was completed in 1912. On January 22 of that year, a proud Flagler rode the first passenger train into Key West, marking the completion of the railroad's oversea connection to Key West and the linkage by railway of the entire
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of cement, 96,000 tons of rock, 78,000 tons of gravel, and 300,000 cubic yards of coralline rock. In addition to this the constructors had to shift some 2,000 tons of reinforced steel, 70,000 pine piles, and approximately 100,000 tons of spoil for filling in shallows and making up embankments.
287:, one of the most destructive hurricanes that ever visited the Florida Keys inflicted severe damage to a great number of miles of embankment and track—not, however, to the great steel and concrete bridge structures that formed the vital part of the project, including the Seven Mile Bridge.
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from their piers due to the failure of the contractors to put in the necessary number of anchor bolts. A study of the destructive force of these storms was responsible for many radical changes in construction plans, and as a result the present work is practically storm proof.
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rust-proof paint had been numerous, based, for the most part, on the anti-fouling compositions of red-lead similar to that used on ships' keels. The rails are also exposed to the rapid corrosion set up by the saturated air and are treated with a special protective covering.
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solution to the problem. Material for such a coating was discovered in the marine marl deposits along the line. This form of clay spread over the surface of the embankments, hardened on exposure to the air, and was capable of withstanding the heaviest seas.
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Never one to rest on his laurels, Flagler next sought perhaps his greatest challenge: the extension of the Florida East Coast Railway to Key West, a city of almost 20,000 inhabitants located 128 miles (206 km) beyond the tip of the Florida
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But even these two great bridges did not suffice. Before the island of Key West could be reached by the railway, yet another 2,500 odd feet had to be traversed, and Coe decided that a viaduct would be best for this remaining part of the route.
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construction. As resident manager, he constructed viaducts totaling nearly 12 miles over open water. Coe had charge of the entire engineering and inspection departments, the labor force, and all floating equipment.
302:, was acclaimed as the longest bridge in the world, an engineering marvel. It was the most costly of all Flagler's bridges in the Key West Extension. From 1912 until portions of the Extension were destroyed by
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required many engineering innovations as well as vast amounts of labor and monetary resources. At one time during construction, 4,000 men were employed. During the seven-year construction, three
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was reached on January 29, and West Palm Beach on March 22. Further extension southwards did not begin until June 1895, when a favorable deal was signed with Miami-area business interests.
499:"The Seven Mile Bridge," PHOTOGRAPHS WRITTEN HISTORICAL AND DESCRIPTIVE DATA, Historic American Engineering Record National Park Service, Department of the Interior, Washington D.C. 20240
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of the Overseas Railroad, the Key West Extension of the Florida East Coast Railway. Completed in 1912, the Overseas Railroad was heavily damaged and partially destroyed in the
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After the Key West Extension was completed, Coe was named Engineer Maintenance of Way for the railroad, a position he held until he volunteered for military service in 1917.
39:, which, when completed in January 1912, was acclaimed as the longest bridge in the world and an engineering marvel. Later, Coe was appointed the first city manager of
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19:(December 24, 1865 – March 5, 1939) was an American master bridge builder and railroad civil engineer, who supervised the planning and building of the
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330:. The Florida East Coast Railway was financially unable to rebuild the destroyed sections, so the roadbed and remaining bridges were sold to the state of
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the railroad was finished in 1912, range had been extended on the ships to such a degree that Key West was no longer a desirable stopover for coal.
74:, earning a degree in engineering in 1889. After graduation, Coe held various engineering positions in the rapidly expanding railroad industry.
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had not planned, designed and built the route and bridge infrastructure that were subsequently used to construct the original highway.
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Later, he returned to France and oversaw the dredging of the harbor and the construction of the great docks and terminals the Port of
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to the engineering and management skills of those connected with its construction, all under Coe’s leadership and supervision.
551:"LIBERTY SQUARE: 1933-1987, THE ORIGINS AND EVOLUTION OF A PUBLIC HOUSING PROJECT," by Paul S. George and Thomas K. Petersen,
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Flagler also believed that linking Key West to the mainland after the United States announced in 1905 the construction of the
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blasted out of the coral, and lifted onto floating platforms, where it was flung into large mechanical mixers.
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was constructed in phases by the Florida East Coast Railway and its predecessor systems. Founder and owner
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In 1910, Coe was promoted to division engineer with responsibility for overseeing construction of the
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drying and draining of these embankments took a long while owing to the saturated state of the soil.
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trade, as the opening of the canal would allow significant trade opportunities with the west.
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In 1905, he joined the Florida East Coast Railway, first as resident managing engineer of the
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In January 1912, when it was completed, the Seven Mile Bridge, linking the Florida Keys to
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63:, one of the nine children of Sylvester Coe and his wife, Ann (née Rowlands), a native of
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land development and trading along the line became one of his most profitable endeavors.
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At the outbreak of World War I, at the age of 51, Coe enlisted as captain of Company A,
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Originally known as the Knights Key-Pigeon Key-Moser Channel-Pacet Channel Bridge, the
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From 1936 to 1939, Coe was in charge of the public housing program in Miami and built
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570:"History and Background: Construction of the Old Bridge," by Dan Gallagher, Ph.D
322:(US 1) through the Florida Keys. Large parts of it were built on the former
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was reached on March 3 of the following year. By April, the construction reached
364:(1925–29)) and succeeded General Dawes, as colonel. After the war, President
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as an adviser, and Coe spent two years rebuilding the Balkan railroads.
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The railroad to Key West continued in operation for 23 years until on
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Highway Engineer and Contractor World, Volume 19, Oct. 1921, 286
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of Miami in 1921. In 1922, he was appointed county engineer of
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In 1891, Coe married Luela Joy. The couple had five children.
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was constructing a line southwards from Daytona Beach in 1894.
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Jacksonville, St. Augustine and Indian River Railway
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Coe’s involvement in building the Seven Mile Bridge
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437:adopted resolutions recognizing Coe’s services.
93:over open ocean, a feat never before attempted.
318:is a 113-mile (181.9 km) highway carrying
310:Legacy of Seven Mile Bridge construction feat
279:Magnitude of Coe’s engineering accomplishment
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97:Involvement with Florida East Coast Railway
210:Detail of Moser Channel Bridge Center Pier
448:Coe died at age 73, on March 5, 1939, in
409:Coe received the following decorations:
477:, Iowa City, Iowa, March 11, 1939, p.4.
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610:People from Washington County, Iowa
513:, Volume 63, August 3, 1917, p. 218
411:Chevalier Legion of Honor of France
362:Vice President of the United States
615:People from St. Augustine, Florida
370:King of Serbs, Croats and Slovenes
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605:People from Duval County, Florida
415:Order of the White Eagle (Serbia)
395:one set of over 750 housing units
193:threatened to halt the project.
17:Clarence Stanley Coe (C. S. Coe)
454:St. Augustine National Cemetery
511:Railway Age and Railway Review
113:Before it became the FEC, the
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425:; and (conferred by General
375:Coe was appointed the first
342:War service and later career
328:Labor Day Hurricane of 1935
174:, would be of advantage to
101:The railroad line south of
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21:Florida East Coast Railway
431:Order of the Purple Heart
585:American civil engineers
473:"Col. Clarence S. Coe,"
423:Order of the Black Eagle
185:The construction of the
475:Iowa City Press Citizen
401:residents of the city.
368:recommended Coe to the
197:east coast of Florida.
72:University of Minnesota
70:He was educated at the
450:St. Augustine, Florida
435:United States Congress
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525:Professional Engineer
488:Route May, circa 1893
381:Duval County, Florida
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55:Early life and career
452:, and was buried in
353:, commanded by Col.
527:, Volumes 3-4, 1919
419:Order of St. Xavier
351:17th U.S. Engineers
304:a hurricane in 1935
81:, having charge of
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133:Key West Extension
79:Key West Extension
590:Civil engineering
366:Herbert C. Hoover
217:Seven Mile Bridge
187:Overseas Railroad
139:Overseas Railroad
91:Seven Mile Bridge
65:Llangollen, Wales
25:Seven Mile Bridge
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564:Additional links
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49:Duval County
29:Florida Keys
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600:1939 deaths
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357:(later the
245:Bahia Honda
150:to Key West
119:Fort Pierce
51:, Florida.
579:Categories
460:References
191:hurricanes
157:peninsula
553:Tequesta
388:Bordeaux
296:Marathon
148:en route
33:Marathon
332:Florida
83:viaduct
45:Florida
433:. The
429:) the
405:Awards
176:Cuban
172:canal
41:Miami
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