Famous Bridges

1. The Golden Gate Bridge links San Francisco with Marin County in absolute splen-dor. The bridge is one of the architectural marvels of the Twentieth Century and a testa-ment to human strife, as it was constructed during the years of the Great Depression. For years, the Golden Gate Bridge held the title as the longest suspension bridge in the world.

Before its completion in 1937, the bridge was considered impossible to build, due to persistently foggy weather, 60-mile-per-hour winds, and strong ocean currents, which whipped through a deep canyon below. In fact, the bridge is commonly known as the "Bridge that couldn't be built." Despite these unforgiving natural elements, the bridge was constructed in a little more than four years. The total cost was $35 million. The total length of the bridge spans 1.2 miles. Eleven men lost their lives during the construction of the bridge.

Even today, the massive spans of the bridge are often shrouded in fog. The bridge sways 27 feet to withstand winds of up to 100 miles per hour. International Or-ange was the color chosen for the bridge because it blended well with the bridge's natu-ral surroundings. The two great cables extending from the bridge contain 80,000 miles of steel wire, which is enough to circle the equator three times. The concrete poured to cement the bridge into the stormy waters below could have also been used to pave a five-foot sidewalk from New York to San Francisco.

Because of the Golden Gate Bridge, San Francisco is one of the premier skyline cities in the nation. It was a triumphant day in the history of the city when the bridge was completed on May 27, 1937. Over 200,000 people celebrated the grand opening of the Golden Gate Bridge by walking its length. The following day, a dedication ceremony was held to officially christen what would become the architectural trademark of the city. The regular flow of vehicular traffic began the next day.

Efforts to begin the construction on the bridge began as early as 1928. The process would entail the efforts of six counties in Northern California. In 1928, the coun-ties formed a Golden Gate Bridge and Highway District. In 1930, the voters appropri-ated a $35 million bond issue to finance the building of the bridge. For many years fol-lowing, Joseph Baerman Strauss, a distinguished engineer, dreamed of raising a span across the Golden Gate. It was in response to his vision that people first started saying that the bridge could not be built. But, amazingly enough, Strauss held fast to his vision, and a span was eventually raised across the Golden Gate Bridge. The actual work on the bridge began on January 5, 1933. It was completed four-and-one-half years later. The result astounded the fiercest of Strauss's critics. To this day, the bridge is admired for its magnitude and beauty.

The bridge is nothing short of a powerful force meant to combat nature. The often mighty winds from the Pacific Ocean are sustained by a mid span swing of 27 feet. The two towers of the bridge rise an impressive 746 feet, which is 191 feet taller than the

Washington Monument. The pier of the bridge is only 1,215 feet from the shore, the dis-tance between the two towers that support the cables, which in turn, support the floor of the bridge is 4,200 feet. These two cables are the largest bridge cables ever made at a little over 361 feet in diameter.

Today, pedestrians and bicyclists are still allowed to cross the bridge on path-ways with breathtaking views of the city, Alcatraz, and the Marin Headlands. The bridge toll for vehicles is $3 when entering San Francisco.

The first exit of the Marin side of the bridge is Visa Point, which provides a mag-nificent view of the San Francisco skyline. But, the best way to view the bridge is to walk across. This usually takes about an hour.

2. The Sydney Harbour Bridge, also affectionately known as the 'Coathanger', was opened on March 19th 1932 by Premier Jack Lang, after six years of construction. Made of steel the bridge contains 6 million hand driven rivets. The surface area that re-quires painting is equal to about the surface area of 60 sports fields. The Bridge has huge hinges to absorb the expansion caused by the hot Sydney sun. You will see them on either side of the bridge at the footings of the Pylons.You can have a close hand look while you are in Sydney by visiting the South Eastern Pylon. It is a walking trip and recommended for the fit only. It is a longish walk to get to the base of the Pylon and then there are 200 steps to the top. Entry for adults is now $8.50 (23 June 2003), kids between 8 and 12 years three dollars and under 8 years its free. (Prices valid until 30 November 2003).

The views and photo opportunities are fantastic. (If you can make it, we've got to say it is tough). There is a great display on how the thing was built. It has a similar place in Sydney history to the Statue of Liberty in New York as far as many migrants to Aus-tralia go. In sight of the bridge you knew you had made it.

The displaced peoples of Europe who came to Australia in the days of the grand ships can get very misty when you ask them what they felt when they saw this grand old arch on their arrival in Sydney from the aftermath of World War Two as they sailed up Port Jackson (Sydney Harbour). The old Bridge has been replaced as "the" landmark of Sydney by the bold architecture of the Opera House

When it opened it cost a car six pence to cross. A horse and rider was 3 pence. These days a return trip (for some reason the only kind) costs two dollars twenty (gst). Horses and riders are banned, that's the changing times. You can walk across free and you are allowed to bicycle in a special lane.

Sydney Harbour Bridge is the world's largest (but not longest as thats the New River Gorge in the USA) steel arch bridge, and, in its beautiful harbour location, has be-come a renowned international symbol of Australia.

Its total length including approach spans is 1149 metres and its arch span is 503 metres. The top of the arch is 134 metres above sea level and the clearance for ship-ping under the deck is a spacious 49 metres. The total steelwork weighs 52,800 tonnes,

including 39,000 tonnes in the arch. The 49 metre wide deck makes Sydney Harbour Bridge the widest Longspan Bridge in the world.

3. The Akashi Kaikyo Ôhashi, with a main span of 1,991m, is the longest suspension bridge in the world: one and a half times as long as the Humber Bridge or the Golden Gate Bridge. It opened in 1998 and connects the city of Akashi, just west of Kobe, Japan, to the neighboring island of Awaji. The entire bridge is 3.9km long.

The bridge was originally planned by the Japanese National Railways (now JR) in the mid-1950's, as part of a rail link between the islands of Honshu andShikoku. In 1975, af-ter an exhaustive study, the Japanese government elected to build JR's bridge, the Seto Bridge, over a much shorter span closer toOkayama. Ten years later, the government approved the Akashi Kaikyo project as a freeway bridge, placing it under the control of the Honshu Shikoku Bridge Authority that was then supervising the construction of the Seto Bridge. Construction began in 1988 and took ten years to complete. Both of the 283m main towers are built on reinforced concrete caissons set underwater, each 80m in diameter. The ground below the Akashi Strait wasdredged to a depth of 60m to ac-commodate the caissons, which together have to support 120,000 tons. Each anchor-age is built on reclaimed land using 350,000 tons of concrete. The cables in the bridge contain a total of 300,000 km of wire: each cable is about a meter in diameter and con-tains nearly 40,000 strands of wire. If that isn't enough engineering to make your mind boggle, consider this: the bridge is strong enough to withstand an earthquakeat 8.5 on the Richter scale (and it did, in fact, withstand the Great Hanshin Earthquake while it was under construction).

If you don't have a car, the best way to see the bridge is to get on a westbound train on the Kobe Line from Osaka or Sannomiya, and keep an eye out on the left side of the train, which will pass directly under the bridge. See Japanese engineering at its finest, and make sure you come home through Kansai International Airport.

The Sydney Harbour BridgeThe Golden Gate Bridge

The Sydney Harbour Bridge

The Akashi Kaikyo Ôhashi

Ms. RobertsKevin ValenciaTech Draw 2/5/10

Tech Draw Homework

What are the six major types of bridges?The six major types of bridges are the following:

Beam Bridges: Beam bridges are horizontal beams supported at each end by piers. The earliest beam bridges were simple logs that sat across streams and similar simple structures. In modern times, beam bridges are large box steel girder bridges. Weight on top of the beam pushes straight down on the piers at either end of the bridge. They are made up mostly of wood or metal.

Cantilever Bridges: Cantilever bridges are built using cantilevers—horizontal beams that are supported on only one end. Most cantilever bridges use two cantilever arms ex-tending from opposite sides of the obstacle to be crossed, meeting at the center. The largest cantilever bridge is the 549-metre (1,800 ft) Quebec Bridge in Quebec, Canada.

Arch Bridges: Arch bridges are arch-shaped and have abutments at each end. The earliest known arch bridges were built by the Greeks and include the Arkadiko Bridge. The weight of the bridge is thrust into the abutments at either side. Dubai in the United Arab Emirates is currently building the Sheikh Rashid bin Saeed Crossing which is scheduled for completion in 2012. When completed, it will be the largest arch bridge in the world.

Suspension Bridges: Suspension bridges are suspended from cables. The earliest suspension bridges were made of ropes or vines covered with pieces of bamboo. In modern bridges, the cables hang from towers that are attached to caissons or coffer-dams. The caissons or cofferdams are implanted deep into the floor of a lake or river. The longest suspension bridge in the world is the 12,826 feet (3,909 m) Akashi Kaikyo Bridge in Japan. See simple suspension bridge, stressed ribbon bridge, underspanned suspension bridge, suspended-deck suspension bridge, and self-anchored suspension bridge.

Cable-stayed Bridges: Like suspension bridges, cable-stayed bridges are held up by cables. However, in a cable-stayed bridge, less cable is required and the towers holding the cables are proportionately shorter. The first known cable-stayed bridge was de-signed in 1784 by C.T. Loescher. The longest cable-stayed bridge is the Sutong Bridge over the Yangtze River in China.

Truss Bridges: Truss bridges are composed of connected elements. They have a solid deck and a lattice of pin-jointed or gusset-joined girders for the sides. Early truss bridges were made of wood, and later of wood with iron tensile rods, but modern truss

bridges are made completely of metals such as wrought iron and steel or sometimes of reinforced concrete. The Quebec Bridge, mentioned above as a cantilever bridge, is also the world's longest truss bridge.