The Golden Gate Bridge

The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening of the San Francisco Bay onto the Pacific Ocean. As part of both U.S. Route 101 and State Route 1, it connects the city of San Francisco on the northern tip of the San Francisco Peninsula to Marin County.

The Golden Gate Bridge had the longest suspension bridge span in the world (4,200 foot) when it was completed in 1937 and has become an internationally recognized symbol of San Francisco and California.

Despite its red appearance, the colour of the bridge is officially an orange vermilion called international orange. The colour was selected by consulting architect Irving Morrow because it blends well with the natural surroundings yet enhances the bridge's visibility in fog.

The bridge's two towers rise 746 feet making them 191 feet taller than the Washington Monument. The five lane bridge crosses Golden Gate Strait which is about 400 feet, or 130 meters, deep. The bridge consists of two towers of 746 feet this makes it 191 feet higher than the Washington Monument. The five lanes of the Golden Gate Bridge are about 400 feet or 130 meters deep.

The towers that support the Golden Gate Bridge's suspension cables are smaller at the top than at the base, emphasizing the tower height of 500 feet above the roadway Coit Tower is another San Francisco landmark with an Art Deco design.

Linking San Francisco with Marin County the Golden Gate Bridge is a 1.7 mile-long suspension bridge that can be crossed by car, on bicycles or on foot. On an average day 118,000 vehicles cross the bridge. The bridge has six total lanes of vehicle traffic, and walkways on both sides of the bridge.

The speed limit on the Golden Gate Bridge was reduced from 55 mph (89 km/h) to 45 mph (72 km/h) on 1 October 1983. The eastern walkway is for pedestrians and bicycles during the weekdays and during daylight hours only, and the western walkway is open to bicyclists on weekday afternoons, weekends, and holidays.

It united three Boroughs of New York: Manhattan, the Bronx, and Queens. It remains the largest vertical-lift bridge in the world. It joins three giant bridges into one and consists of 13,500 feet of elevated viaduct and fourteen miles of roadway, all travelling over Randall's and Ward's Islands. Since its completion, the span length has been surpassed by eight other bridges. It still has the second longest suspension bridge main span in the United States, after the Verrazano Narrows Bridge in New York City.

History

The idea to cross the Golden Gate strait was originated as early as 1872 by a railroad magnate. Not until 1916 was a serious attempt made to make the crossing. Bridge designer Joseph Strauss felt he could cross the Gate with a huge suspension bridge and do it for under $30 million dollars.

In 1921, Strauss finalized a plan and set out to convince San Francisco citizens and leaders that it could, and should, be done. In 1919 the visionary engineer, Joseph B. Strauss, came to San Francisco to inspect the bridge site. He was convinced he could build a bridge spanning the Golden Gate.

In November 1930, a major hurdle was overcome; six Northern California counties, including Marin and San Francisco, voted in favour of a $35 million bond measure to finance the construction of the bridge. To celebrate this important victory, every store in Marin County closed at 3 p.m. on November 12, so that the entire community could attend a football game in San Rafael and watch an air circus. The evening culminated with a parade, illuminated floats & fireworks.

The Golden Gate Bridge

Golden Gate Bridge construction commenced on January 5, 1933 and lasted four and a half years. The resulting structure, renowned for the simplicity and elegance of its design, has become emblematic of the San Francisco Bay Area and has achieved fame worldwide.

On May 27, 1937, the bridge opened to pedestrians with much fanfare. Enthusiastic crowds picnicked on the middle of bridge and there was a great procession at mid-day with 20,000 marchers and floats representing every county in the bridge district.

The GGB opened to vehicular traffic on May 28, 1937 at twelve o'clock noon, ahead of schedule and under budget, when President Franklin D. Roosevelt pressed a telegraph key in the White House announcing the event The Marin Headlands side of San Francisco's GGB is a great place to take pictures such as this July 4th fireworks photo and watch freighters and sailboats cruise under the bridge.

The bridge required so much concrete that cement factories throughout the Eastern United States that closed as a result of the Great Depression were re-opened just to make the concrete for the bridge. To make the wood for the forms that held the concrete, whole forests were cut down in Oregon.

5,000 men at a time worked directly on the bridge. These men were only the ones actually put the bridge together; tens of thousands more worked to prepare the materials that made up the bridge. Completing the bridge took 31 million work-hours, in 134 cities, across 20 states. In the middle of the Depression this project was so huge that it alone buoyed the economy of the whole country.

The year 2007 marks the 70th birthday of possibly the most beautiful, and certainly the most photographed, bridge in the world. San Francisco's Golden Gate Bridge, named for the strait leading from the Pacific Ocean to the San Francisco Bay, spans tidal currents, ocean waves, and battering winds to connect The City by the Bay with the Redwood Empire to the north.

Millions of visitors come to the bridge each year. The speed limit of the bridge is now only 45 miles per hour and traffic fines have been doubled for the bridge. A $3 fee is collected for southbound traffic and tourists who want to ride their bikes across the bridge can take advantage of the 10-foot wide sidewalks. 

The Panama Canal

The Panama Canal is a major ship canal that traverses the Isthmus of Panama in Central America, connecting the Atlantic and Pacific Oceans. Construction of the canal was one of the largest and most difficult engineering projects ever undertaken. It has had an enormous impact on shipping between the two oceans, replacing the long and treacherous route via the Drake Passage and Cape Horn at the southernmost tip of South America.

The 50 miles long (80 km) international waterway known as the Panama Canal allows ships to pass between the Atlantic Ocean and Pacific Ocean, saving about 8000 miles (12,875 km) from a journey around the southern tip of South America, Cape Horn. The Canal itself is made up of the Gaillard Cut channel and the artificial Gatun Lake. The lake was formed by the damming of the Chagres River.

The chambers of the locks are wide and 33.53 meters from 304.8 meters long. The water to get on and off the ships in each set of locks is obtained by gravity from Lake Gatun. The water enters the locks through a main sewer system, which extends below the chambers of the locks from the side walls and the central wall.

The narrowest part of the Canal is the Culebra Cut, which extends from the far north of the Pedro Miguel Locks to the southern tip of Lake Gatun in Gamboa. This segment, approximately 13.7 km long, was dug through rock and limestone of the Cordillera Central. The maximum size of vessel that can use the canal is known as Panamax; an increasing number of modern ships exceed this limit, and are known as post-Panamax or super-Panamax vessels.

Since opening, the canal has been enormously successful, and continues to be a key conduit for international maritime trade. The canal can accommodate vessels from small private yachts up to large commercial vessels. For every ship that passes the canal is used about 197 million litres of fresh water, which flows by gravity through the locks and dumped into the ocean. The Canal operates 24 hours a day, 365 days a year, providing transit service to ships of all nations without discrimination.

History

The earliest mention of a canal across the Isthmus of Panama dates back to 1534, when Charles V, Holy Roman Emperor and King of Spain, ordered a survey for a route through Panama that would ease the voyage for ships travelling to and from Spain and Peru. During his expedition of 1788–1793 Alessandro Malaspina demonstrated the feasibility of a canal and outlined plans for its construction.

An all-water route between the oceans was still seen as the ideal solution, and the idea of a canal was enhanced by the success of the Suez Canal. The French, under Ferdinand de Lesseps, began construction on a sea level canal through what was then Colombia's province of Panama, on January 1, 1880. The French began work in a rush with insufficient prior study of the geology and hydrology of the region.

In 1885, due to the tremendous problems encountered in trying to excavate a sea-level canal, the plan was changed to include a single, temporary lock and other adjustments in order to speed up the availability of the canal for traffic. Still, it was of no use.

Among other problems, sea level on the Caribbean side of Panama is lower than on the Pacific side. In addition, disease, particularly malaria and yellow fever, sickened and killed vast numbers of employees, ranging from labourers to top directors of the French company. These conditions made it impossible to maintain an experienced work force as fearful technical employees quickly returned to France.

Panama Canal

The appraisal of the company's belongings including equipment, maps, and the value of the land already excavated was very high, and in 1894, a new company, the Compagnie Nouvelle du Canal de Panama, was created in France to attempt to finish the canal. All involved thought of this as an impossible feat by the French, and ideas ran strong to sell the Canal Zone possibly to the United States.

In 1899 the US Congress created an Isthmian Canal Commission to examine the possibilities of a Central American canal and to recommend a route. The commission first decided on a route through Nicaragua, but later reversed its decision.

In November 1903, Phillipe Bunau-Varilla, Panama's ambassador to the United States, signed the Hay-Bunau Varilla Treaty, granting rights to the United States to build and indefinitely administer the Panama Canal. Bunau-Varilla, although serving as Panama's ambassador, was a French citizen, and was not authorized to sign treaties on behalf of Panama without the review of the Panamanians.

The United States, under President Theodore Roosevelt bought out the French equipment and excavations for US$40 million, and began work on May 4, 1904, after helping Panama achieve the separation from Colombia by deploying troops and naval forces to stop Colombia from stopping the rebellion against Colombian governance, created by the United States of America. The United States paid Colombia $25,000,000 in 1921; seven years after completion of the canal, for redress of President Roosevelt's role in the creation of Panama, and Colombia recognized Panama under the terms of the Thomson-Urrutia Treaty.

Chief Engineer (1905–1907), John Frank Stevens', primary achievement in Panama was in building the infrastructure necessary to complete the canal. He rebuilt the Panama Railway and devised a system for disposing of soil from the excavations by rail. He also built proper housing for canal workers and oversaw extensive sanitation and mosquito control programmes that eliminated yellow fever and other diseases from the Isthmus.

With the diseases under control, and after significant work on preparing the infrastructure, construction of an elevated canal with locks began in earnest and was finally possible. The Americans also gradually replaced the old French equipment with machinery designed for a larger scale of work, quickening the pace of construction, President Roosevelt delivered medals for all workers who spent at least two years in the building to commemorate their contributions to the construction of the canal. These medals featured Roosevelt's likeness on the front, the name of the recipient on one side, and the worker's years of service, as well as a picture of the Culebra Cut on the back.

The building of the canal was completed in 1914, two years ahead of the target date of June 1, 1916. The canal was formally opened on August 15, 1914 with the passage of the cargo ship Ancon.

By the 1930s it was seen that water supply would be an issue for the canal; this prompted the building of the Madden Dam across the Chagres River above Gatun Lake. The dam, completed in 1935, created Madden (later Alajuela) Lake, which acts as additional water storage for the canal.

After the war, United States' control of the canal and the Canal Zone surrounding it became contentious as relations between Panama and the U.S. became increasingly tense. Many Panamanians believed that the Canal Zone rightfully belonged to Panama; protests as well as the increased military presence.

Negotiations toward a new settlement began in 1974, and resulted in the Torrijos-Carter Treaties. Signed by President of the United States Jimmy Carter and Omar Torrijos of Panama on September 7, 1977, this set in motion the process of handing the canal over to Panamanian control for free as long as Panama signed a treaty guaranteeing the permanent neutrality of the canal (Neutrality Treaty) and allowed the U.S. to come back anytime. Though controversial within the U.S., the treaty led to full Panamanian control effective at noon on December 31, 1999, and control of the canal was handed over to the Panama Canal Authority (ACP). 

 

The Itaipu Hydroelectric Power Plant

The Itaipu Hydroelectric Power Plant is located on the Paraná River between Brazil and Paraguay. The Paraná River is the seventh largest river in the world and the second largest in South America. Itaipu Dam is the world’s largest hydroelectric power facility and it is a joint effort of the governments of Brazil and Paraguay.

The project ranges from Foz do Iguaçu, in Brazil, and Ciudad Del Este in Paraguay, in the south to Guaíra and Salto Del Guaíra in the north. The name Itaipu was taken from an isle that existed near the construction site. In the Guarani language, “Itaipu” means "the sound of a stone".

The Itaipu Reservoir is 170 km long with an area of 1.35 km2 and has a volume at maximum normal level of 29 billion tons of water. It consists of a series of various types of dams the height of the dam reaches 196 m, its length 7.76 km. The Powerhouse is located at the toe of the main Dam, most of it on the river bed and the rest on the Diversion Channel.

The main structure, a hollow, concrete gravity dam, has a powerhouse capable of generating 14,000 megawatts (MW) of electricity. The main powerhouse has 18 Francis turbines each with a rated power of 715 MW. The Spillway is located on the right bank, and it has 14 segmented sluice gates with a total discharge rate of 62,200 cubic meters per second.

The volumes of construction in Itaipu are also impressive. The volume of iron and steel utilized in the Dam structure would be enough to build 380 Eiffel Towers, and the volume of concrete used in Itaipu represents 15 times the volume utilized to build the Channel Tunnel between France and England.

The power plant is a major tourist attraction in the Foz do Iguacu area. More than nine million visitors from 162 countries have visited the structure since it was completed in 1991.

History

On June 22, 1966, the Ministers of Foreign Affairs of Brazil, Juracy Magalhaes, and of Paraguay, Sapena Pastor, signed the "Act of Iguaçu ". A study was carried out under this Act that assessed the potential hydraulic resources of the Paraná River, which is jointly occupied by the two countries. In 1967, the Brazilian-Paraguayan Joint Technical Commission was established to carry out the study and the development of the Paraná River.

On April, 26, 1973, the two governments of the states signed a treaty "for the development of the hydroelectric resources of the Paraná River" and founded ITAIPU Binacional (cooperation with the legal, administrative and financial capacities and technical responsibility to plan set up and operate the plant) in May, 17, 1974.

Itapu Dam

The construction work started in 1975, reaching its peak in 1978 with 30 000 people at work. Monthly on-site concrete production reached 338 000 m³. In total, 15 times the mass of concrete used for the "Euro Tunnel" was supplied.

It took almost three years for workers to carve a 1.3 mile long, 300 foot deep, 490 foot wide diversion channel for the river. Fifty million tons of earth and rock were removed in the process. Engineers chose a hollow gravity dam because it required 35 percent less concrete than a solid gravity dam. The hollow dam is still heavy and sturdy enough to resist the thrust of water entirely by its own weight.

Sometimes the dam can get blocked with mud and silt. It is expensive to clean the dam out. The mud and silt can cause diseases in the water in the reservoir. Unless the water in the reservoir is cleaned, people can get these diseases. The land behind the dam and reservoir had to be flooded. Much of this land was rainforest and the trees had to be cut down. Many parrots died because their homes in the trees were destroyed.

In 1982 the land behind the dam was flooded and within 14 days the reservoir was created. Unit 1 started to operate in December 1983. Electrical grid connection to Paraguay was established in March 1984, Brazil was connected 5 months later. In March 1991 the last Unit (No.18) was put into operation.

The magnitude of the project also can be demonstrated by the fact that in 1995 Itaipu alone provided 25% of the energy supply in Brazil and 78% in Paraguay. 

 

The Empire State Building located at Fifth Avenue at 34th Street in Manhattan. Ever since it was built, the Empire State Building has captured the attention of young and old alike, every year, millions of tourists flock to the Empire State Building to get a glimpse from its 86th and 102nd floor observatories; the image of the Empire State Building has appeared in hundreds of ads and movies.

The Building Materials on the exterior is Indiana limestone and granite, trimmed with aluminium and chrome nickel steel from the 6th floor to the top, the interior the lobby was made by Ceiling high marble, imported from France, Italy, Belgium and Germany. The facade is composed of more than 200,000 cubic feet of Indiana limestone and granite, and utilizes several setbacks to offset the optical distortion.

It has height 448 meters to top of antenna, 391 meters to 102nd floor observatory, 320 meters to 86th floor observatory. And cover an area of 83,860 square feet. The top of the Empire State Building is lit up at night in different colours to celebrate various holidays. For a long time after Sept. 11, 2001, it was continuously lit red, white, and blue. The height of the antenna has been increased from 443.2 meters to 448.7 meters.

The Empire State Building Observatory on the 86th and 102nd floors provides incredible views of Manhattan. It's one of the most popular tourist destinations in New York City on a clear day you can see up to 80 miles in any direction.

The observatory is open daily from 9:30am to midnight. All visitors must enter through the Fifth Avenue entrance and security is strict so expect a wait. You'll want to bring some quarters for the coin operated telephoto viewers on the observation deck.

History

The construction began on March 17, 1930, built in the midst of the Depression, it was, and still remains a testament to American fortitude and ingenuity, the building was the center of a competition between Walter Chrysler (Chrysler Corp.) and John Jakob Raskob (creator of General Motors) to see who could build the tallest building.

Designed by architectural practice Shreve, Lamb and Harmon Associates, construction of the building superstructure began on the site of the old Waldorf-Astoria Hotel on 17 March, 1930; although excavation for the foundations had commenced on 22 January, 1930. One of the enduring achievements of the Empire State Building was the speed of its construction.

Empire State Building

By October 3, 1930, there were 88 floors finished and only 14 to go. These top floors took the form of a distinctive tower of glass, steel, and aluminium. The tower is about 200 ft. high and topped with a dome.

Construction of the building requiring 7 million man hours, 60,000 tons of steel and 10 million bricks proceeded at a record pace even though the stock market crash of 1928 happened just a few weeks after the massive project was begun. It was built in just 18 months and was one of the first to employ the then new fast track construction technique.

In 1985 a 22 story television antenna was attached to the top of the building and serves a lightning rod protecting surrounding buildings. The rod absorbs around 100 lightning strikes each year.

For 40 years after it was constructed, it held the record for being the largest skyscraper in the world. The building has starred in over 90 movies, and it remains one of New York City's most popular tourist attractions.

Although the Empire State Building is no longer the world's tallest building, it is still visited by millions of tourists each year and has been featured in over 90 famous movies like King Kong or Sleepless in Seattle.

It was official opening in May 1, 1931, by President Herbert Hoover, who pressed a button in Washington, D.C. to turn on the building's lights.

The Empire State Building is a legend. An international icon, it has been visited by more than 117 million people, who come to marvel at the 80 mile view into New Jersey, Pennsylvania, Connecticut and Massachusetts. 

 

Delta Works

The flooding in 1953 made it very clear how vulnerable the land and the people living there were. Therefore a huge effort the Delta Works project was made to create a new and better protection to make sure this would not happen again.

The Delta Works protects a large area of land around the Rhine-Meuse-Scheldt delta from the sea. Delta Works is a very complicated collection of locks, sluices, channels, bridges, slides, dams, dikes, storm surge barriers and gates working together.

The aim of the dams, sluices, and storm surge barriers was to shorten the Dutch coastline, thus reducing the number of dikes that had to be raised. This dam consists of several strings of gates and their massive supporting pylons which, in normal weather, allow tidal sea waters to ebb and flow in the Eastern Schelde estuary, thus benefiting the fish, bird life and the local fisheries. The four great estuaries in the south-western Netherlands should be closed with dams. These closures should be done in a special order because of tidal movements of shipping and fishing, this guarantees for the economy of the country.

The piers and their mechanisms had to be lifted into precise positions in the estuary. But the type of equipment needed for such gargantuan and specialized tasks did not exist anywhere in the world; it had to be invented. The piers support 300- to 500-ton steel gates and their hydraulic machinery, as well as a roadway above and load-bearing beams below.

The Oosterscheldedam is on one of the two artificial islands situated in Zeeland, just an hour and a half driving distance from Amsterdam and half an hour from Dordrecht where the structure is located; it is a recommend for those interested in water management. Three kilometres long, this anti-tempest dam is constituted of 65 pillars between which one can slide 62 iron flood-gates.

The height of one pillar is 38 meter and its weight 18.000 tons. When the sea becomes dangerous, one hour is enough to lower the flood gates. This system affords to keep 75% of the tide amplitude as well as the fishing industry, the breed of mussels and oysters and above all, the unique eco-system of The Biesbosch.

One of the latest improvements of the Delta plan was the storm surge barrier in the New Waterway near Hoek van Holland built in 1997. It consists of two enormous doors mounted on swing arms that can be used to close the estuary if storm and high water requires in order protecting the country.

History

During the night of January 31, 1953, to force 12 north westerly windstorm pounded the coast of Zeeland. The weakened dikes, drenched with water, ultimately gave way, flooding the islands of Goeree-Overflakkee, Tholen and Schouwen-Duiveland. The result was disastrous 1835 fatalities, 100000 evacuees, and 200000 hectares of land under water.

After that a commission was installed which had to come up with a plan to research the causes and seek measures to prevent such disasters in future. They revised some of the old plans; the plans were made to connect the South Holland and Zeeland islands by dams. The combination of these plans and dams was called the Delta Plan. The Dutch government unanimously accepted the Delta Act in 1958, thus laying the foundation for the Delta Works. In 1959, the Delta Law was passed, in order to organise the construction of the dams.

Delta Works

The plan consisted of blocking the estuary-mouths of the Oosterschelde, the Haringvliet and the Grevelingen. This reduced the length of the dikes exposed to the sea by approximately 400 miles (640 km).

The dikes along these waterways were to be heightened and strengthened. The works would be combined with road and waterway infrastructure to stimulate the economy of the province of Zeeland and improve the connection between the port of Rotterdam and Antwerp.

The Delta Works consist of more than dams and dikes alone; locks are also needed for transporting high water to the Rhine. Therefore drainage locks have been built in the Haringvliet. These locks began operating in 1971 and have 17 openings, each 56.5 meters wide. The Brouwers Dam in the Brouwershaven Gat was completed in 1972.

Oosterschelde Flood Barrier was created to prevent the creation of too many freshwater areas in Holland, the flood barrier locks are usually kept open and only close during times of extremely high storm tides. This structure, one of the largest in the world, cost 5.5 billion guilders to build and was opened on October 4, 1986.

This project led to dangerous tides causing dangerous floods have been reduced, now are lovely areas to explore by boat. Some of the uncovered shores have become recreation parks. Many sandbars and shores, however, especially in the Oosterschelde, are part of an important nature reserve. It was the largest project of its kind anywhere in the world and took 30 years to build. It is known as the Delta Project.

The CN Tower

The CN Tower is the World's Tallest Building and Free-Standing Structure and has the world's highest public observatory, although it is not considered to be a traditional building. At a height of 553.33m, it is an important telecommunications hub. It is almost twice as tall as the Eiffel Tower and more than three times the height of the Washington Monument.

Located in Toronto, Ontario, Canada at the southern end of town to the north shore of Lake Ontario, the CN Tower is easily accessible from many major streets and highways. It was erected as a communications and tourist tower.

The CN Tower consists of a main hexagonal hollow pillar of concrete containing the elevators, stairwells and power and plumbing connections. To the main pillar are attached the broadcast antenna and the two main visitors area. The main pillar has three supporting legs giving it the appearance of a camera tripod.

Some floors of the Main Level are open to the public. At 342 m is the Glass Floor and Outdoor Observation Deck. The Glass Floor consists of thermal glass units that are 64mm thick. The floor has an area of 24sq metre and can withstand a pressure of 600psi. At 346m is the Horizons Cafe and Look Out level.

There is a rotating restaurant at 351m called the 360 Restaurant. It revolves completely in 360 degrees every 72 minutes. The rotation is slow enough that you can enjoy the fantastic views of Toronto without realizing your view is changing every moment. Below the Main Level is the tower's microwave receiver shaped like a big white donut.

The Sky Pod is presently the highest observation deck in the world. From here, you can see 100-120 km away, to the city of Rochester across Lake Ontario in the US, and see the mist rising from Niagara Falls.

The CN Tower has the tallest metal staircase in the world. At the 1776th step, the staircase reaches the Main Level. The staircase is intended only for emergency use, and is not open to the public outside three times a year during the charity stair-climbing events.

At the base of the Toronto CN tower is an attraction called the Tour of the Universe. For the price of entry you can walk through a simulated space port, see a laser show and experience what it’s like to fly through space. Tour of the Universe is open daily from 10am until 10pm. The CN Tower is open 364 days a year (closed on Christmas Day). Hours of Operation are daily from 9am-10pm January-April; 8am-11pm May-December. Cost is $16 for adults.

History

The CN tower history dates back to February 6, 1973 when the tower construction began by Canadian National Railway. The CN originally refers to "Canadian National", it was built on former railway land which the railway company had planned for a development called Metro Centre.

The CN Tower was constructed when Toronto was experiencing an economic boom. Indeed the Canadian National Railway had planned it to demonstrate the strength of Canadian industries, and CN in particular. The late 1960s and early 1970s was a particularly prosperous time for Toronto, which see a sprout of large skyscrapers. This causes some difficulties in broadcasting to the downtown area, due to reflections from these tall buildings. The solution is to raise the antenna above all these buildings. At that time, most data communications use point-to-point microwave links that require line of sight links.

CN Tower

A Toronto firm prepared the initial design, enlisting the aid of engineering experts the world over. Their original plan showed three towers linked by structural bridges. Gradually the design evolved into a single 1,815.5-foot-tall tower comprised of three hollow "legs".

Giant backhoes excavated more than 62,000 tons of earth with a depth of 50 feet from along the shore of Lake Ontario in Toronto harbour. Next, pressed concrete and reinforced steel were arranged in a Y-shaped pattern 22 feet thick. The foundation took four months to complete. The tower itself presented a challenge of height never before met by the technique of poured concrete. Concrete was poured 24 hours a day, five days a week, and as it hardened, the mold moved by means of a ring of hydraulic jacks. The ascending slip form gradually decreased in girth to give the tower its tapering shape.

When the tower reached the 335 m. mark, the builders made preparations for the SkyPod, a seven story structure housing two observation decks, a revolving restaurant, a nightclub, and broadcasting equipment. The SkyPod is anchored by 12 steel and wooden brackets that were slowly pushed up the tower by 45 hydraulic jacks.

The concrete tower continues above the SkyPod, ending at the Space Deck 446 m up. The Space Deck offers to the visitors a breathtaking vista from a glass-enclosed balcony. On a clear day they might be able to glimpse sites 75 miles away.

For the last phase of construction, a Sikorsky Skycrane helicopter arrived to install the tower's over 100 m. communications mast. One by one the helicopter lifted about 40 seven-ton sections of the mast to the top of the tower. When the sections were in place, they were secured by a total of 40,000 bolts. Afterward, the entire mast was covered by a fibreglass reinforced sheathing to prevent icing.

On April 2, 1975 when the OLGA helicopter lifted the 44th and final piece of the CN Tower's antenna into place, the CN Tower joined the ranks of 17 other great structures that had previously held the title of World's Tallest Free-Standing Structure.

Completed in 1975, the tower had cost $57 million to build, a bargain compared with other modern wonders. It was finished on April 2, 1975, and opened to the public June 26, 1976.

Twenty-four years later, it is the centre of telecommunications for Toronto serving 16 Canadian television and FM radio stations, the workplace of up to 550 people throughout the year, and one of Toronto's premier entertainment destinations.

Ross McWhirter, editor of the Guinness Book of World Records, was on hand to record the milestone for history and since then, the CN Tower has received numerous mentions in the famous book including the World's Longest Metal Staircase and most recently, the World's Highest Wine Cellar.

In 1995, the CN Tower was classified by the American Society of Civil Engineers as one of the Seven Wonders of the Modern World. In 1996, the CN Tower's classification was officially changed to the World's Tallest Building and Free-Standing Structure.

The World's Tallest Building shares this designation with the Itaipu Dam on the Brazil/Paraguay border, the Golden Gate Bridge in San Francisco, the Panama Canal, the Chunnel under the English Channel, the North Sea Protection Works off the European coast, and the Empire State Building.

In past years, the CN Tower has supported its vision of Toronto's premier entertainment destination by totally renovating and redesigning 360 Restaurant, building the World's Highest Wine Cellar, and adding two new elevators. On June 26, 1997, TrizecHahn Corporation, one of North America's largest real estate companies signed a long term operating and management lease for the CN Tower and its adjoining base lands. A $26 million entertainment expansion and revitalization opened its doors on June 26, 1998. This massive expansion and total CN Tower revitalization plan will launch the CN Tower into the next millennium as a major international entertainment destination.

Each year, approximately 2 million people visit the World's Tallest Building to take in the breathtaking view and enjoy all of the attractions the CN Tower has to offer. While at the CN Tower, you’ll also have the chance to browse through souvenir shops. 

 

The Euro Tunnel

The Channel Tunnel also called the Euro Tunnel is a rail link under the English Channel between Cheriton near Folkestone, Kent, and Coquelles near Calais. The tunnel is one of the greatest civil engineering projects of the 20th century, has an ultimate design capacity of 600 trains per day each way.

The Channel Tunnel is 50 km (31 mi) long, out of which 39 km (24 mi) are undersea; it comprises two railway tunnels and a service tunnel. The two rail tunnels have 7.6 m in diameter, and the central tunnel has 4.8 m in diameter that is used for maintenance and ventilation, and if necessary, passengers could escape into it on foot in the event of an emergency on board a train. There are also several "cross-over" passages that allow trains to switch from one track to another.

The depth of the tunnels below the seabed averages about 45 m. The total number of track is 195 kilometers (120 miles), of which 45 kilometers (28 miles) outside the terminal in the United Kingdom and 50 km (31 miles) to the French terminal. The journey takes less than 30 minutes.

HISTORY

The Channel Tunnel is the largest privately financed engineering project in history, the United Kingdom and France announced plans to construct the Channel Tunnel on January 20, 1986.

The French mining engineer Albert Mathieu Favier is credited with first suggesting a tunnel under the Channel, in 1802. Numerous other schemes emerged over the years. In 1875 the Channel Tunnel Company set up by the British engineer John Hawkshaw was given authority to build a tunnel by the governments of both Britain and France. In 1881 a new Act gave powers to a rival scheme promoted by Hawkshaw's former colleague William Low.

The Channel Tunnel 

Trial tunnelling started but soon stopped because of concerns about military defense. Between 1882 and 1950 the British Parliament rejected ten Channel Tunnel bills, mostly for national security reasons. Tunnelling was revived in 1922 but soon abandoned again.

The present tunnel is based on a scheme drawn up in 1960 by the Channel Tunnel Study Group, alliance of British and French companies; Technical Studies, Inc. of the United States; and the Suez Canal Company. Work stopped in January 1975, after two access tunnels 740 m long had been dug. In the 1980s the construction company Tarmac took over from RTZ as prime mover behind the project. And in this year the Channel Tunnel suffer its first attempt, but the project was abandoned soon after and workings lay dormant for a hundred years. In November 1984 the two governments of France and the United Kingdom decided to support resumption and in April 1985 potential promoters were asked to submit schemes.

TML was a consortium of the British construction firms Tarmac, Wimpey, Costain, Balfour Beatty and Taylor Woodrow (Translink Contractors), with the French firms Bouygues, Dumez, Spie Batignolles, SAE, and SGE (Transmanche Construction). In October 1987, Eurotunnel, a private company, the company created by TML and its banks, was floated on the stock market. Eurotunnel became the client and TML its contractor. Eurotunnel gained 55 years concession in the work of high speed rail link between London and Paris.

Construction of the tunnels began in September 1987. Boring machines drove from the French and British coasts, both inland towards the terminals and out to sea. In 1988, international treaties were signed and once more excavation work began in earnest.

The two sections of the service tunnel were the first to link up, breaking through in December 1990. The tunnelling companies were Graham Fagg of the United Kingdom and Philippe Cozette of France, and they achieved a tunnelling rate of 426 m in one week. A total of 7 million tons of spoil was removed. At the peak of activity, 15,000 construction workers were on site and over seven years to complete.

The tunnel cost nearly $16 billion in United States dollars, more than twice the original cost estimates. The Chunnel was officially opened by Elizabeth II of the United Kingdom and French President Francois Mitterrand during a ceremony on May 6, 1994. Nearly 7 million passengers take the 35 minute journey travel through the tunnel every year. In its first six years of operation, 112 million passengers used the service.