Panama Canal Railway
The Panama Canal Railway is a railway line linking the Atlantic Ocean to the Pacific Ocean in Central America. The route stretches 47.6 miles across the Isthmus of Panama from Colón to Balboa. Because of the difficult physical conditions of the route and state of technology, the construction was renowned as an international engineering achievement, one that cost US$8 million and the lives of an estimated 5,000 to 10,000 workers. Opened in 1855, the railway preceded the Panama Canal by half a century. Known as the Panama Railroad Company when founded in the 19th century, today it is operated as Panama Canal Railway Company. Since 1998 it has been jointly owned by Kansas City Southern and Mi-Jack Products and leased to the government of Panama; the Panama Canal Railway provides both freight and passenger service. The principal incentive for the United States to build the rail line was the vast increase in passenger and freight traffic to California following the 1849 California Gold Rush; the United States Congress had provided subsidies to companies to operate mail and passenger steamships on the coasts, supported some funds for construction of the railroad, which began in 1850.
Referred to as an inter-oceanic railroad when it opened, it was also described by some as representing a "transcontinental" railroad, despite transversing only the narrow isthmus connecting the North and South American continents. For a time the Panama Railroad owned and operated ocean-going ships that provided mail and passenger service to a few major East Coast and West Coast cities, respectively; the infrastructure of this railroad was of vital importance to the construction of the Panama Canal over a parallel route half a century later. The Spanish improved what they called the Camino Real, the Las Cruces trail and maintained for transportation of cargo and passengers across the Isthmus of Panama; these were the main routes across the isthmus for more than three centuries. By the 19th century businessmen thought it was time to develop a cheaper and faster alternative. Railroad technology had developed in the early 19th century. Given the cost and difficulty of constructing a canal with the available technology, a railway seemed the ideal solution.
President Bolívar of La Gran Colombia commissioned a study into the possibility of building a railway from Chagres to the town of Panama City. This study was carried out between 1829, just as railroads were being invented; the report stated. However, the idea was shelved. In 1836, United States President Andrew Jackson commissioned a study of proposed routes for inter-oceanic communication in order to protect the interests of Americans traveling between the oceans and those living in the developing Oregon Country of the Pacific Northwest; the United States acquired a franchise for a trans-Isthmian railroad. In 1838 a French company was given a concession for the construction of a road, rail, or canal route across the isthmus. An initial engineering study recommended a sea-level canal from Limón Bay to the bay of Boca del Monte, 12 miles west of Panama; the proposed project collapsed for lack of funding needed. Following the United States' acquisition of Alta California in 1846 and the Oregon Territory in 1848, following the Mexican–American War and with the prospective movement of many more settlers to and from the West Coast, the United States again turned its attention to securing a safe and speedy link between the Atlantic and Pacific oceans.
In 1846 the United States signed a treaty with Colombia by which the United States guaranteed Colombian sovereignty over Panama and was authorized to build a railroad or canal at the Panamanian isthmus, guaranteeing its open transit. In 1847, a year before gold was discovered in California, Congress authorized subsidies to run two lines of mail and passenger steamships, one in the Atlantic and one in the Pacific; the Atlantic lines ran from New York City, Havana and New Orleans, Louisiana, to Panama's Chagres River on the Caribbean Sea, at a $300,000 subsidy. The proposed Pacific line ran with three steamships from Panama City, Panama to California and Oregon on the Pacific Coast, at a $200,000 subsidy. None of the steamships used in the Pacific was built. In 1847, the east–west transit across the isthmus was by native dugout canoe up the dangerous Chagres River. Travelers had to go overland by mules for the final 20 miles over the old Spanish trails; the trails had fallen into serious disrepair after some 50 years of no maintenance.
A transit from the Atlantic to the Pacific or vice versa would take four to eight days by dugout canoe and mule. The transit was fraught with dangers, travelers were subject to contracting tropical diseases along the way. William H. Aspinwall, the man who had won the bid for the building and operating the Pacific mail steamships, conceived a plan to construct a railway across the isthmus, he and his partners created a company registered in New York, the Panama Railroad Company, raised $1,000,000 from the sale of stock, hired companies to conduct engineering and route studies. Their venture ha
Air draft
Air draft is the distance from the surface of the water to the highest point on a vessel. This is similar to the "deep draft" of a vessel, measured from the surface of the water to the deepest part of the hull below the surface, but air draft is expressed as a height, not a depth; the vessel's "clearance" is the distance in excess of the air draft which allows a vessel to pass safely under a bridge or obstacle such as power lines, etc. A bridge's "clearance below" is most noted on charts as measured from the surface of the water to the under side of the bridge at Mean Highest High Water, the most restrictive clearance; the height of the tide at any time below its highest point at MHHW will increase the clearance under the bridge. In 2014, the United States Coast Guard reported that 1.2% of the collisions it investigated in the recent past were due to vessels attempting to pass underneath structures with insufficient clearance. At several bridges, such as the Gerald Desmond Bridge in Long Beach, California, NOAA has installed an "Air Gap" measuring device that measures the distance from its sensor on the bridge to the water surface and can be accessed by marine pilots and ship's masters to aid them in making real time determination of clearance.
The Bridge of the Americas in Panama limits which ships can traverse the Panama Canal due to its height at 61.3 m above the water. The world's largest cruise ships, Oasis of the Seas, Allure of the Seas and the Harmony of the Seas will fit within the canal's new widened locks, but they are too tall to pass under the Bridge of the Americas at low tide, unless the Bridge of the Americas is raised or replaced in the future. New ships are built not clearing 65 m; the Suez Canal Bridge has a 70-metre clearance over the canal, 8.7 m higher than Panama. The Bayonne Bridge is an arch bridge connecting New Jersey with New York City, the roadbed was raised to 66 m, a height suitable for larger container ships to pass, the modification cost $1.32 billion. Structural clearance Structure gauge Tower Bridge Cargo ship Size categories Chart datum
Panama Canal Authority
The Panama Canal Authority is the agency of the government of Panama responsible for the operation and management of the Panama Canal. The ACP took over the administration of the canal from the Panama Canal Commission, the joint US–Panama agency that managed the canal, on December 31, 1999, when the canal was handed over from the United States to Panama as per the Torrijos–Carter Treaties; the Panama Canal Authority is established under Title XIV of the National Constitution, has exclusive responsibility for the operation, management, preservation and modernization of the canal. It is responsible for the operation of the canal in a safe, continuous and profitable manner; the Organic Law of the Panama Canal Authority, passed on June 11, 1997, provides the legal framework for the canal's organization and operation. Because of its unique nature, the ACP has financial autonomy, as well as ownership of the canal's assets; the Board of Directors is responsible for establishing policies for the operation and modernization of the Canal, as well as supervising its management pursuant to the National Constitution, the Panama Canal Authority Organic Law, the Regulations thereto appertaining.
The board of directors is made up as follows: One Director designated by the President of the Republic, who shall chair the Board of Directors and shall have the rank of Minister of State for Canal Affairs. One Director designated by the Legislative Branch, who may be appointed or removed thereby. Nine Directors appointed by the President of the Republic with the consent of the Cabinet Council and ratification by an absolute majority of the members of the Legislative Assembly; the Directors shall serve in their posts for a term of 9 years, may only be removed for the reasons set forth in Article 20 of the Panama Canal Authority Organic Law. The Panama Canal is defined by law to be an inalienable patrimony of the Republic of Panama. Therefore, it may not be sold, mortgaged, or otherwise encumbered or transferred; the Panama Canal Authority Board of Directors is responsible for establishing policies for the operation and modernization of the Canal, as well as supervising its management. At present, the Panama Canal Authority Board of Directors is made up of the following members: Official website
Panamax
Panamax and New Panamax are terms for the size limits for ships travelling through the Panama Canal. The limits and requirements are published by the Panama Canal Authority in a publication titled "Vessel Requirements"; these requirements describe topics like exceptional dry seasonal limits, propulsion and detailed ship design. The allowable size is limited by the width and length of the available lock chambers, by the depth of water in the canal, by the height of the Bridge of the Americas since that bridge's construction; these dimensions give clear parameters for ships destined to traverse the Panama Canal and have influenced the design of cargo ships, naval vessels, passenger ships. Panamax specifications have been in effect since the opening of the canal in 1914. In 2009 the ACP published the New Panamax specification which came into effect when the canal's third set of locks, larger than the original two, opened on 26 June 2016. Ships that do not fall within the Panamax-sizes are called super-Panamax.
The increasing prevalence of vessels of the maximum size is a problem for the canal, as a Panamax ship is a tight fit that requires precise control of the vessel in the locks resulting in longer lock time, requiring that these ships transit in daylight. Because the largest ships traveling in opposite directions cannot pass safely within the Culebra Cut, the canal operates an alternating one-way system for these ships. Panamax is determined principally by the dimensions of the canal's original lock chambers, each of, 110 ft wide, 1,050 ft long, 41.2 ft deep. The usable length of each lock chamber is 1,000 ft; the available water depth in the lock chambers varies, but the shallowest depth is at the south sill of the Pedro Miguel Locks and is 41.2 ft at a Miraflores Lake level of 54 ft 6 in. The clearance under the Bridge of the Americas at Balboa is the limiting factor on a vessel's overall height for both Panamax and Neopanamax ships; the maximum dimensions allowed for a ship transiting the canal using the original locks and the new locks are: Overall: 950 ft. Exceptions: Container ship and passenger ship: 965 ft Tug-barge combination, rigidly connected: 900 ft overall Other non-self-propelled vessels-tug combination: 850 ft overall.
Width over outer surface of the shell plating: 106 ft. General exception: 107 ft, when draft is less than 37 ft in tropical fresh water. New Panamax increases allowable width to 49 m; the maximum allowable draft is 39.5 ft in Tropical Fresh Water. The name and definition of TFW is created by ACP using the freshwater Lake Gatún as a reference, since this is the determination of the maximum draft; the salinity and temperature of water affect its density, hence how deep a ship will float in the water. Tropical Fresh Water is fresh water of Lake Gatún, with density 0.9954 g/cm3, at 29.1 °C. The physical limit is set by the lower entrance of the Pedro Miguel locks; when the water level in Lake Gatún is low during an exceptionally dry season the maximum permitted draft may be reduced. Such a restriction is published three weeks in advance, so ship loading plans can take appropriate measures. New Panamax increases allowable draft to 15.2 m, however due to low rainfall, the canal authority limited draft to 43 feet when the new locks opened in June 2016, increasing it to 44 feet, in August "based on the current level of Gatun Lake and the weather forecast for the following weeks."
Vessel height is limited to 190 ft measured from the waterline to the vessel's highest point. Exception: 205 ft when passage at low water at Balboa is possible. All exceptions are allowed only after specific request and an investigation, on a once- or twice-only basis. A Panamax cargo ship would have a DWT of 65,000–80,000 tonnes, but its maximum cargo would be about 52,500 tonnes during a transit due to draft limitations in the canal. New Panamax ships can carry 120,000 DWT. Panamax container ships can carry 5,000 twenty-foot equivalent units; the longest ship to transit the original locks was San Juan Prospector, now Marcona Prospector, an ore-bulk-oil carrier, 973 ft long, with a beam of 106 ft. The widest ships to transit are the four Iowa-class battleships, which have a maximum beam of 108 ft, leaving less than 6 in margin of error between the ships and the walls of the locks; as early as the 1930s, new locks were proposed for the Panama Canal to ease congestion and to allow larger ships to pass.
The project was abandoned in 1942. On October 22, 2006, the Panama Canal Authority held a referendum for Panamanian citizens to vote on the Panama Canal expansion project; the expansion was approved with support from about 78 % of the electorate. Construction began in 2007, after several delays, the new locks opened for commercial traffic on 26 June 2016; the plans to build another set of larger locks led to the creation of the Neopanamax or New Panamax ship classification, based on the new locks' dimensions of 427 m in length, 55 m in beam, 18.3 m in depth. Naval architects and civil engineers began taking into account these dimensions for container
Colón, Panama
Colón is a city and sea port in Panama, beside the Caribbean Sea, lying near the Atlantic entrance to the Panama Canal. It is the capital of Panama's Colón Province and has traditionally been known as Panama's second city, it was located on Manzanillo Island, surrounded by Limon Bay, Manzanillo Bay and the Folks River. S. Army base, as well the former Canal Zone towns of Cristobal and Coco Solo; the city was founded by the United States in 1850, as the Atlantic terminal of the Panama Railroad under construction to meet the demand during the California Gold Rush for a fast route to California. For a number of years early in its history, the sizable United States émigré community called the town Aspinwall after Panama Railroad promoter William Henry Aspinwall, while the city's Hispanic community called it Colón in honor of Christopher Columbus; the city was founded on the western end of a treacherously marshy islet known as Manzanillo Island. As part of the construction of the Panama Railroad, the island was connected to the Panamanian mainland by a causeway and part of the island was drained to allow the erection of permanent buildings.
Much of the city was destroyed in the Burning of Colón during the Colombian Civil War of 1885, again during a massive fire in 1915. The Great Colon Fire of April 13–14, 1940 destroyed one third of the city. Fort De Lesseps was a small U. S. Army Coast Artillery Corps fort located at the northern tip of the city, it was named after the canal developer Ferdinand de Lesseps. In 1948, the southeastern corner of Manzanillo Island was designated as the Colón Free Trade Zone; the Free Trade Zone has since been expanded through land reclamation on the Folks River and annexation of parts of France Field and Coco Solo. During its heyday, Colón was home to dozens of nightclubs and movie theaters, it was known for its citizens' civic pride, orderly appearance, outstanding native sons and daughters. Politically instigated riots in the 1960s destroyed the city's municipal palace and signaled the start of the city's decline, further accelerated by the military dictatorships of Omar Torrijos and Manuel Noriega from 1968 to 1987.
A massive restoration and reconstruction project, involving parks and historic buildings and monuments, began in late 2014 and uses the hashtags #RenovaciónColón, #CiudadDeColón, #RenovationColon and #CityOfColon. The First Baptist Church of Colón, Panama, is one of the buildings whose renovation has been completed; the main setting of the short story "Latarnik" by Polish author Henryk Sienkiewicz is the lighthouse in Aspinwall. Colón is the setting of Argentine writer César Aira’s short 2002 novel Varamo. Like most of the Caribbean coast of Central America, Colón possesses an wet tropical climate owing to the powerful, wet trade winds flowing onto high mountains throughout the year. Unlike most parts of this coast, however and March are sufficiently dry that Colón fits into the tropical monsoon climate category rather than a tropical rainforest climate as found in most Caribbean coastal areas. Nonetheless, the June-to-December period, with an average monthly rainfall of around 415 millimetres or 16.3 inches, is so wet that Colón rivals Honduras’ La Ceiba as the wettest sizable city in Central America.
Colón's population in 1900 was 3,001. It grew with the building of the Panama Canal, becoming 31,203 by 1920. In 2000, the population was around 204,000. With the city's economic decline, many of its upper and middle-class residents left, reducing its ethnic diversity. European and American expatriate communities, as well as Panamanians of Greek, Jewish and South Asian heritage, started moving to Panama City, to former Canal Zone towns, overseas. Today, sizable South Asian and Arab communities live in the remaining prosperous areas of the city, as well as in gated communities outside it; the majority of the city's population is of mixed mestizo-hispanic ancestry. Colón was home to some of the best-educated and most well-heeled Panamanian families of West Indian heritage, such as the Drews, the Fords, the Moodys, the Robinsons, the Beebys, the Archibolds, the Edwards, the Crowns, the Hoys, the Warehams, the Abrahams, the McKintoshs. From these families sprang the teachers, doctors, engineers and politicians that contributed to the city's prosperity.
Most of them left the city for the United States or the United Kingdom. Their influence may still be seen, however, in their descendants. Colón was home to Las Amigas de la Caridad, a charitable organization of women of Caribbean descent; the organization met in the home of Gladys Booth Ford and her stepdaughter Ruby Ford Drew at Calle 7 and Avenida Sta. Isabel. Ruby Drew was a long-standing member of Christ Church by the Sea. Colón is home to Correcaminos Colon, 2016 Basketball Champion of Panama and member of the FIBA Americas League; the team plays its home games at the Arena Panamá Al Brown. Kenneth B. Clark, educator, testified in Brown v. Board of Education Pedro Heilbron, CEO of Copa Holdings Eric Jackson, publisher and talk show host John McCain, American politician, Senator from Arizona from 1986 until his death in 2018, 2008 Republican presidential nominee, born in the U. S. Navy hospital at the Coco Solo submarine base. Juan Williams, political commentator on Fox News Billy Cobham, songwriter, bandlead
Bridge of the Americas
The Bridge of the Americas is a road bridge in Panama, which spans the Pacific entrance to the Panama Canal. Designed by Sverdrup & Parcel, it was completed in 1962 at a cost of US$20 million, connecting the north and south American land masses. Two other bridges cross the canal: the Atlantic Bridge at the Centennial Bridge; the Bridge of the Americas crosses the Pacific approach to the Panama Canal at Balboa, near Panama City. It was built between 1962 by the United States at a cost of US$20 million. From its completion in 1962 until the opening of the parallel Centennial Bridge in 2004, the Bridge of the Americas was a key part of the Pan-American Highway; the Bridge of the Americas increases road traffic capacity across the Canal. Two earlier bridges cross the Canal, but they use moveable designs and have limited traffic capacity; these earlier spans include a small swinging road bridge, built into the lock structure at Gatún, a swinging road/rail bridge constructed in 1942 at Miraflores. The Centennial Bridge was constructed to eliminate the bottleneck of, reduce traffic congestion on, the Bridge of the Americas.
The bridge is a cantilever design. The bridge has a total length of 1,654 m in 14 spans, abutment to abutment; the main span measures the tied arch is 259 m. The highest point of the bridge is 117 m above mean sea level. Ships must cross under this bridge when traversing the Panama Canal, are subject to this height restriction; the world's largest cruise ships, Oasis of the Seas, Allure of the Seas, Harmony of the Seas and the Symphony of the Seas will fit within the canal's widened locks, but they are too tall to pass under the Bridge of the Americas at low tide, unless the Bridge of the Americas is raised in the future. The bridge has wide access ramps at each end, pedestrian walkways on each side. From the beginning of the French project to construct a canal, it was recognised that the cities of Colón and Panamá would be split from the rest of the republic by the new canal; this was an issue during construction, when barges were used to ferry construction workers across the canal. After the canal opened, the increasing number of cars, the construction of a new road leading to Chiriquí, in the west of Panama, increased the need for some kind of crossing.
The Panama Canal Mechanical Division addressed this in August 1931, with the commissioning of two new ferries, the Presidente Amador and President Washington. This service was expanded in August 1940, with additional barges serving the military. On June 3, 1942, a road/rail swing bridge was inaugurated at the Miraflores locks. Still, it was clear. To meet the growing needs of vehicle traffic, another ferry, the Presidente Porras, was added in November 1942; the idea of a permanent bridge over the canal had been proposed as a major priority as early as 1923. Subsequent administrations of Panama pressed this issue with the United States, which controlled the Canal Zone. A contract worth $20,000,000 was awarded to John F. Beasly & Company who built the bridge out of steel and reinforced concrete, the project was initiated in a ceremony which took place on December 23, 1958, in the presence of United States Ambassador Julian Harrington, Panamanian President Ernesto de la Guardia Navarro. Construction began on October 12, 1959, took nearly two and a half years to complete.
The inauguration of the bridge took place on October 1962, with great ceremony. The ribbon was cut by Maurice H. Thatcher, after which those present were allowed to walk across the bridge; the ceremony was given full nationwide coverage on television. These proved inadequate and pro-Panamanian protesters disrupted the ceremony removing the memorial plaques on the bridge; when opened, the bridge was an important part of the Pan-American Highway, carried around 9,500 vehicles per day. The bridge therefore became a significant bottleneck on the highway, which led to the construction of the Centennial Bridge, which now carries the Pan-American Highway too. On May 18, 2010, the bulk cargo ship Atlantic Hero struck one of the protective bases of the bridge after losing engine power blocking that section of the canal to shipping traffic; the bridge did not receive damage and there were no fatalities. In December 2010, the Centennial Bridge access road collapsed in a mudslide, commercial traffic was diverted to the Bridge of The Americas.
The bridge was named "Thatcher Ferry Bridge", after the original ferry which crossed the canal at about the same point. The ferry was, in turn, named after Maurice H. Thatcher, a former member of the Canal Commission, who introduced the legislation which created the ferry. Thatcher cut the tape at the inauguration of the bridge; the name was unpopular with the government of Panama, which preferred the name "Bridge of the Americas". The Panamanian view was made official by a resolution of the National Assembly on October 2, 1962, ten days before the inaugurati
Cable-stayed bridge
A cable-stayed bridge has one or more towers, from which cables support the bridge deck. A distinctive feature are the cables or stays, which run directly from the tower to the deck forming a fan-like pattern or a series of parallel lines; this is in contrast to the modern suspension bridge, where the cables supporting the deck are suspended vertically from the main cable, anchored at both ends of the bridge and running between the towers. The cable-stayed bridge is optimal for spans longer than cantilever bridges and shorter than suspension bridges; this is the range within which cantilever bridges would grow heavier, suspension bridge cabling would be more costly. Cable-stayed bridges have been known since the 16th century and used since the 19th. Early examples combined features from both the cable-stayed and suspension designs, including the Brooklyn Bridge; the design fell from favor through the 20th century as larger gaps were bridged using pure suspension designs, shorter ones using various systems built of reinforced concrete.
It once again rose to prominence in the 20th century when the combination of new materials, larger construction machinery, the need to replace older bridges all lowered the relative price of these designs. Cable-stayed bridges date back to 1595, where designs were found in Machinae Novae, a book by Venetian inventor Fausto Veranzio. Many early suspension bridges were cable-stayed construction, including the 1817 footbridge Dryburgh Abbey Bridge, James Dredge's patented Victoria Bridge and the Albert Bridge and Brooklyn Bridge, their designers found. John A. Roebling took particular advantage of this to limit deformations due to railway loads in the Niagara Falls Suspension Bridge; the earliest known surviving example of a true cable-stayed bridge in the United States is E. E. Runyon's intact steel or iron Bluff Dale Suspension bridge with wooden stringers and decking in Bluff Dale, Texas, or his weeks earlier but ruined Barton Creek Bridge between Huckabay and Gordon, Texas. In the twentieth century, early examples of cable-stayed bridges included A. Gisclard's unusual Cassagnes bridge, in which the horizontal part of the cable forces is balanced by a separate horizontal tie cable, preventing significant compression in the deck, G. Leinekugel le Coq's bridge at Lézardrieux in Brittany.
Eduardo Torroja designed a cable-stayed aqueduct at Tempul in 1926. Albert Caquot's 1952 concrete-decked cable-stayed bridge over the Donzère-Mondragon canal at Pierrelatte is one of the first of the modern type, but had little influence on development; the steel-decked Strömsund Bridge designed by Franz Dischinger is, more cited as the first modern cable-stayed bridge. Other key pioneers included Fabrizio de Miranda, Riccardo Morandi, Fritz Leonhardt. Early bridges from this period used few stay cables, as in the Theodor Heuss Bridge. However, this involves substantial erection costs, more modern structures tend to use many more cables to ensure greater economy. Cable-stayed bridges may appear to be similar to suspension bridges, but in fact, they are quite different in principle and in their construction. In suspension bridges, large main cables hang between the towers and are anchored at each end to the ground; this can be difficult to implement. The main cables, which are free to move on bearings in the towers, bear the load of the bridge deck.
Before the deck is installed, the cables are under tension from their own weight. Along the main cables smaller cables or rods connect to the bridge deck, lifted in sections; as this is done, the tension in the cables increases, as it does with the live load of traffic crossing the bridge. The tension on the main cables is transferred to the ground at the anchorages and by downwards compression on the towers. Difference between types of bridges In the cable-stayed bridge, the towers are the primary load-bearing structures that transmit the bridge loads to the ground. A cantilever approach is used to support the bridge deck near the towers, but lengths further from them are supported by cables running directly to the towers; this has the disadvantage, compared to the suspension bridge, that the cables pull to the sides as opposed to directly up, requiring the bridge deck to be stronger to resist the resulting horizontal compression loads. By design all static horizontal forces of the cable-stayed bridge are balanced so that the supporting towers do not tend to tilt or slide, needing only to resist horizontal forces from the live loads.
Key advantages of the cable-stayed form are as follows: much greater stiffness than the suspension bridge, so that deformations of the deck under live loads are reduced can be constructed by cantilevering out from the tower – the cables act both as temporary and permanent supports to the bridge deck for a symmetrical bridge, the horizontal forces balance and large ground anchorages are not required There are four major classes of rigging on cable-stayed bridges: mono, harp and star. The mono design uses a single cable from its towers and is one of the lesser-used examples of the class. In the harp or parallel design, the cables are nearly parallel so that the height of their attachment to the tower is proportional to the distance from the tower to their mounting on the deck. In the fan design, the cables all pass over the top of the towers; the fan design is structurally superior wit
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