The piers are built of stone, the top constructions are mostly made of wood, and the roof is tiled. Both sides of the bridge have wooden railings. The bridge's entire length is 64.4 meters (211 feet), and its corridor is 3.4 meters wide (11 ft). The net height over the water is approximately 10 meters (33 ft).
There are three main types of bridges: cable-stayed, suspension, and truss. A cable-stayed bridge uses towers with cables attached to them that support the decking above the water. This type of bridge is used when you need a long span bridge, such as one that crosses a valley or some other area where building land is limited. A suspension bridge uses large vertical rods called "suspensions" that hold up the decking above the water. These bridges are most often found across small streams or ravines. Truss bridges are composed of X-shaped elements called "trusses" that connect together at their ends to form triangles. They are strong and can carry a lot of weight because there are many connections between the pieces of the truss. However, truss bridges are only useful for short spans and cannot handle heavy traffic like larger bridges can.
Chengyang Bridge is a suspension bridge that crosses the Yangtze River in Chengyang County, Hunan Province, China. It is the longest suspension bridge in Southwestern China.
The bridge is constructed of about 11,000 tons of steel and is coated in Cornish granite and Portland stone. To support the piers, more than 70,000 tons of concrete were dug into the riverbed. The main tower is 165 feet high and the shorter side towers are 98 feet high.
The bridge was designed by Sir John Wolfe-Barry, who also designed London's Victoria Memorial and Waterloo Bridge. It was built by Burns & Co. at a cost of £750,000 (about $1.5 million). The project took ten years to complete at a time when heavy industry dominated British commerce. When it opened for traffic on May 20, 1894, it was the most expensive single structure ever built at that time.
Its length of 1,200 feet makes it the longest continuous truss bridge in the world. The central span is 365 feet long and consists of eight sections each with four Pratt trusses. The total weight of the bridge is about 11,000 tons, which is equivalent to about 220 semi-trailers of truck loaded with sand.
The bridge was declared unsafe due to its age and deterioration of parts, and had been under review for replacement for many years. In 2002, work began to replace the bridge.
The right bridge is made up of nine piers and has a maximum span of 160 meters (525 feet) and a total length of 1,576 meters (5,171 ft). Every day, the bridge transports around 80,000 cars and 190 trains. It also has three large ventilation towers with flashing lights on their tops.
The left bridge is only four meters (13 feet) shorter than the right one. But it uses half as much material: only three piers instead of nine. This saves about $10 million in construction costs per bridge.
Each section of the bridge weighs at least 20 tons, so they are built from multiple segments that can be assembled into one single structure with a crane. The longest piece of concrete used in the project was 45 meters (150 feet) long. The entire bridge consists of 987 sections of which 86 are shown in the image below.
The first section of the Nanjing Yangtze River Bridge was put into place in November 1998 by a team of more than 4,500 people. The whole bridge took ten years to build. It opened for traffic in 2008.
It is the world's second-largest movable bridge after the Myauk-Lumphung Bridge in Thailand. Both bridges are multi-span structures with a main lane in each direction.
When a bridge over a body of water requires piers, foundations are formed by lowering caissons into the riverbed and filling them with concrete. Towers are erected atop caissons in the case of suspension bridges. The initial suspension bridge towers were made of stone, but they are now made of steel or concrete. Wood is still used for some bridge types such as swing bridges and bascule bridges.
The first iron bridge in America was built over the Chickahominy River in 1755. It was a wooden bridge, but it had strong ties that could not be removed after it was built so it can be considered the first American bridge.
The next major development in bridge construction came when Benjamin Franklin proposed an experimental wooden bridge for the Connecticut Colony. The colony's governor agreed, and the bridge was completed in 1753. It was a large structure, about 200 feet long, with 14 wooden arches each weighing about 20 tons. It was a great success, and several more similar bridges were built in the colonies.
In the early 19th century, engineers began to propose building bridges out of iron. One of the first iron bridges in the world was built in 1824 near Dover, England. It was a simple single-span bridge without any trusses or girders, but it showed that iron could be used for large structures.
|Golden Gate Bridge|
|Design||Suspension, Art Deco, truss arch & truss causeways|
|Total length||8,980 ft (2,737.1 m), about 1.7 mi (2.7 km)|
|Width||90 ft (27.4 m)|
A steel-girder bridge The original construction was a steel girder bridge with a continuous haunched main span of 61-101-61 m (201-330-200 ft), steel girder approach spans, and a reinforced concrete deck. 12 concrete piers supported the steel girders. The central pier was 750 mm (29 in) wide by 35 m (115 ft) long, and the outer piers were each 550 mm (22 in) wide by 35 m (115 ft) long.
The total length of the bridge was 9,801 mm (37 miles) with two lanes for motor vehicles and one lane for pedestrians. It connected Kansas to Oklahoma.
The I-40 bridge was built by the Missouri Bridge & Iron Company from 1951 to 1953. The central pier was damaged by an explosion of dynamite on January 23, 1955, but this did not affect its stability or cause it to collapse. The bridge remained open to traffic until it was demolished by explosives on February 4, 2005.
The I-40 Mississippi River Bridge was the longest single-span suspension bridge in the world when it was completed in 1990. The central span was 1,640 feet (500 m) long and rested on top of the river bed. The main cables were composed of 26,000 individual strands of wire that were coated in polyethylene sheathing to prevent moisture from affecting their strength.