Japan. Awaji Island. The longest suspension bridge in the world. Panorama of Akashi-Kaikyo. Virtual tour of Akashi-Kaikyo. Attractions, map, photos, videos “Maiko Kaijo Promenade” gives you the opportunity to see the landscape opening from under the bridge

• Address: Higashimaikocho, Tarumi Ward, Kobe, Hyogo 655-0047, Japan
• Construction type: suspension bridge
• Total length: 3911 m
• Height: 282.8 m
• Date of foundation: April 5, 1998

One of the longest structures on the planet is the Akashi Kaikyō suspension bridge, which is located in. It is also known as Pearl Bridge.

Description of the attraction

Akashi-Kaike is a six-lane road bridge connecting the cities of Awaji (Shikoku Island) and (Honshu). The settlements are separated by the Akashi Strait.

The structure has a length of 3911 m and a height of 282.8 m. The distance between the central supports is 1991 m, the side spans are separated by a gap of 960 m.

The bridge design was developed taking into account special technical features. It can withstand extreme loads, strong winds up to 286 km/h (80 m/s) and earthquakes up to magnitude 8, and can withstand sea currents. The developers were able to achieve such indicators by using two hinged stiffening beams and a unique system of pendulums that work in resonance with the overall structure of the structure.

Scientists have also created special super-strong concrete. It has the properties to harden in any environment and not dissolve in water. A factory for the production of raw materials was built right next to the Akashi Strait. Here they built 2 huge molds so that the pylons could be poured into them later. They were flooded to within 10 cm, despite the strong undercurrent.

Construction Features

The Japanese government decided to create the Akashi-Kaike Bridge in the mid-20th century. It comes after 168 children died on two ferries during a terrible storm. Construction of the bridge began only in 1988.

The cable for the bridge was also developed using special technologies. For this purpose, a wire was created, the strength of which was increased by 2 times compared to conventional structures. Scientists collected 127 five-millimeter wires into one strand, and then 290 such bundles were fastened together. The guide rope connecting the pylons was tensioned using helicopters.

The builders worked in difficult conditions, because they were hampered not only by ships passing by (about 1,400 ships daily), but also by salty water with a strong current and a rather soft bottom.

The official opening of the Akashi-Kaike Suspension Bridge took place in 1998 on April 5. During its construction the following were involved:

• 18100 tons of high-strength steel;
• more than $5 billion;
• about 2 million people.

Today, the cost to cross the bridge is approximately $20. Because of such a high cost, many, as before? cross the strait by ferry or take a bus.

Those who wish to admire Akashi Kaike can do so from the side of the city of Kobe, where a special concrete promenade has been built. The platform is 317 m long and offers stunning views of the bridge. It is especially beautiful at night, when it is illuminated by tens of thousands of lights.

Interesting facts about the bridge

Akashi-Kaike is famous not only in the country, but throughout the world. He achieved fame due to the fact that:

• was twice included in the Guinness Book of Records as the highest and longest bridge on the planet;
• The structural cable consists of 36,830 thousand pieces of wire, which has a total length of 300,000 km. It can wrap around the globe almost 7 times.

How to get there?

The Akashi-Kaike suspension bridge is part of the main highway connecting major cities. From the center you can get here along the Kobe-Awaji-Naruto Expressway. The distance is approximately 35 km.

From Awaji, you can reach it via highways No. 66, 469 and Kobe-Awaji-Naruto Expressway. Travel time will take up to 50 minutes.

The total length of the bridge is 3911 meters, and the distance between the supports is 1991 meters. Due to its size, the bridge was twice included in the Guinness Book of Records. The bridge design has its own special technical features of the bridge, designed to ensure that the bridge can withstand extreme loads. This is a system of double-hinged stiffening beams that allow the bridge to withstand wind speeds of up to 80 meters per second, resist sea currents and withstand earthquakes of magnitude up to 8.5. Special pendulum systems are also used that operate at the resonant frequency of the bridge structure. About 500 billion yen were spent on construction. The bridge connected two large islands of Japan - Honshu and Shikoku. If you want to admire the views from the bridge and the bridge itself, then from the Kobe side there is a 317-meter long concrete promenade specially built for this purpose.

History of construction

The decision to build the bridge was made by the Japanese government back in the late 50s. It was forced to listen to the views of local residents who went on strike after the death of 168 children on two ferries that sank during the storm. However, the matter moved from a dead point only in 1988.

During the construction of Akashi-Kaikyo, the greatest difficulties were created by the sea itself with its salt water, strong currents and soft soil. To prevent the destruction of underwater bridge structures under the influence of sea water, the Japanese invented especially strong, quickly hardening concrete and built a plant for its production near the construction site. This concrete was used to create two huge round platforms, which were poured on the shore and then sunk with incredible precision for their size (the error was only 10 cm). They served as the basis for the pylons, the construction of which became the next stage of construction. Having withstood the 7.3 magnitude earthquake of 1995, the tallest pylons in the world at that time successfully passed the strength test.

The Akashi-Kaikyo Bridge opened on April 5, 1998, providing an alternative to the unsafe ferry crossing.

• If you tie all the cables of the Akashi-Kaikyo Bridge into one line, then they can encircle the globe 7 times!
• Since the construction of the Akashi-Kaikyo Bridge cost the Japanese government almost $5 billion, travel on it is paid - the cost is $20. Therefore, today those who want to save money risk their lives and continue to use the ferry crossing.
• The bridge has an unofficial name - Pearl Bridge.

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Akashi-Kaikyo Bridge at noon

Photo gallery: Akashi-Kaikyo Bridge

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Description: Akashi-Kaikyo Bridge

The city's attractions	Akashi Kaikyo Bridge
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More than a year ago, I climbed three hundred meters high on one of the pylons of the Akashi-Kaikyo suspension bridge located in Japan. The length of the bridge is 3911 meters, the span is almost two kilometers, and construction lasted ten years. You can read about that rise. As often happens in Japan, when they build something huge, a museum of this structure appears nearby. And, as you know, Japanese museums are not just rows of posters and photographs - the Japanese are very strong in modeling, reproducing scaled-down structures with great accuracy, while making much of it interactive. That is, when you press a button, the little men begin to move, the mechanisms begin to rotate, and the like. So in the bridge museum, they reproduced in mock-ups the entire history of construction from the beginning of digging pits to tensioning the cables. The little models amazed me so much that I immediately copied them all onto a semiconductor plate and today I want to show you, accompanied by a short story.

Construction stages can be divided into the following stages:
1. Creation of supports for pylons
2. Creation of coastal supports
3. Construction of pylons
4. Pulling the supporting cables
5. Suspension of bridge trusses

Let's start with the first stage.
The bridge pylons are located in the sea strait, more than 60 meters deep. First of all, special vessels extracted bottom soil in the areas where the supports would be installed.

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At the same time, huge floating hollow cylinders were built on the shore, which were transported by water and sunk in dug pits. The height of the cylinders exceeded sixty meters, so that they rose above the water. Moreover, such colossuses had to be installed in the required positions with centimeter precision, which was successfully accomplished by Japanese engineers.

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After installing the forms of future supports, special water-insoluble concrete began to be poured inside them.

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At the same time, the construction of foundations for coastal supports - anchors for attaching cables - took place on the shore. They differ slightly in design depending on the coast. For the western support, a very deep seventy-meter pit was dug, the walls of which, as they walked, were encased in concrete. This depth, if my memory serves me correctly, is due to the desire to go through sedimentary rocks to solid layers. By the way, on the other side, the depth of the pit was only twenty-three and a half meters.

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After excavation, a metal frame-foundation was built in the shaft and filled with concrete. Then the already assembled future cable-stay fastening unit was installed at the top, tightly connecting it to the foundation.

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And immediately they began to build walls around it.

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At the same time, pylons were built. They were not cast from concrete, but assembled from metal elements. Inside there are elevators, stairs, and vibration compensation pendulums. The latter is an important element of almost all modern Japanese high-rise structures, due to high seismicity. By moving a massive load, such a device allows you to eliminate dangerous deviations from the vertical, maintaining the strength and integrity of the structure.

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After completing the installation of both pylons, workers began pulling the cables. The very first thing, a helicopter transferred the primary cable - essentially a strong centimeter-long plastic rope, onto which, later, they began to gradually hang all the others, increasing the number of threads. To do this, the cable being pulled was attached to the primary cable and began to be pulled. Unwinding from the reel, he pulled the attached cable along with him. After pulling several parallel threads, a temporary canvas was laid on them, along which the workers could walk. After installing the walkways, they began to stretch the threads of the supporting cables and so, gradually, the main cables were assembled, holding the entire weight of the canvas. They have a diameter of 1122 mm and consist of many hexagonal elements, each of which, in turn, consists of 127 steel threads, each with a diameter of 5.23 mm. The total length of all threads (on two cables) is one light second.

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The outside of the cables is wrapped with several layers of insulation. At ground supports, the threads are separated, attaching their ends to the attachment points.

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The final stage was the suspension of the roadway trusses. Farms are very complex, because inside them there is a place for the prospect of a railway line. The truss elements were transported by sea, then lifted up by cranes, where they were assembled and mounted to the suspension points.

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Of course, my story turned out to be very short - almost without numbers, without deadlines and dates. I did not talk about the fact that the main cables in the area of ​​the pylons are subject to constant ventilation to compensate for temperature changes, and I did not talk about the design of the suspensions of the vertical cables to the supporting cables. I didn’t even mention the strong earthquake that happened after the load-bearing cables were pulled and pushed the pylons an extra meter apart. However, I hope that this article gives a general idea of ​​how such bridges are built.

On April 5, 1998, 10 years after construction began, the longest suspension bridge in the world, Akashi Kaike in Japan, was opened.

Akashi Kaike, also known in Japan as Pearl Bridge, has a main span of 1991 meters. The roadway of the bridge has six lanes (three in each direction), located on a beam, which is a through truss 35.5 m wide and 14 m high. The beam is suspended on ropes with a diameter of 1.12 m, which consist of prefabricated strands. The cables pass through two steel pylons with a height of 298 m.

The bridge is located at an altitude of 280 m above sea level and its under-bridge dimension is 1,500 m by 65 m. About 181,400 tons of steel were used in the bridge superstructure and 1.42 million m3 of concrete were used in the foundation.

The bridge cost about 500 billion Japanese yen (US$4.2 billion) to build, so a toll of 2,300 yen (US$20) was set on the assumption that the bridge would pay for itself within 30 years. Now the bridge is used by about 25,000 vehicles every day and the bridge "earns" half a million US dollars daily, so there is hope that it will pay for itself in 20 years, which is good, since many people prefer to travel by bus due to this price.

The Akashi-Kaike Suspension Bridge is located on the Kobe-Naruto Highway, which connects the main island of Honshu and the southern island of Shikoku. This route is the easternmost of three north-south traffic routes, a route approved in 1969 by Japan's national development plan to stimulate local trade and promote industrial development in the region.
On the 81-kilometer Kobe-Naruto route, two bridges were planned to be built, including the longest in the world - Akashi-Kaike. This bridge, with a total length of 3,911 m, crosses the Akashi Strait, connecting the Kobe area of ​​Honshu Island with Awaji Island, the sixth largest island in Japan. The second major bridge on this route, the Ohnaruto Suspension Bridge, was completed in 1995 and connects Shikoku Island to the southern border of Awaji Island. This connection of modern highways, interchanges and bridges allows for a significant expansion of the economy of Awaji Island.

The bridge was built at a depth of 110 meters, subject to tidal currents of 4.5 m/s. The bridge can withstand wind speeds of 80 m/s and potential earthquakes with a magnitude of up to 8.5 on the Richter scale. The bridge is located on layered alluvial and colluvial deposits, above the hard Akasi or Kobi layers. Granite protrudes from a support located on Awaji Island.

The main span was to be 1990 m with two side spans of 960 m each. But after the earthquake on January 17, 1995, called the “Great Khanshchin Earthquake,” these characteristics of the span lengths changed. This earthquake carried out a full-scale test of the pylons. Fortunately, the installation of the span had not yet begun, so only the pylons were in the damage zone; the earthquake caused their stable lateral and vertical displacement from Awaji Island and the anchorage. The pylon has moved 1.3 m to the west and the anchorage has moved 1.4 m, relative to the Kobe pylon and anchorage. This resulted in a 0.8 m increase in span length between the pylons and a 0.3 m increase in span length on the south side. Pylon from the side of Fr. Awaji was moved 0.2 m vertically downwards and the anchorage was raised 0.2 m. The main cable slack was reduced by 1.3 m.
The earthquake caused a month-long delay in construction, during which time the bridge was carefully inspected for damage. The increased distance between the pylons was accommodated by redesigning the two central panels, which were 0.4 m longer than the original ones.
The anchorage measures 63 m by 84 m in plan. The western anchor abutment of the Akashi-Kaike Bridge (from the side of Awaji Island) rests directly on a granite foundation, the eastern (from the side of Honshu Island) foundation is a cylindrical concrete mass with an outer diameter of 85 m and a height of 64.5 m, buried in bedrock ( Pliocene sandstone and shale), lying at a depth of 55 m under a layer of sandy-gravel soil.

The construction of this foundation was carried out in the following order:
1. construction of an external enclosing lintel with a thickness of 2.2 m and a depth of 75.5 m using the “wall in soil” method;
The wall was divided into sections, which were developed using grips. The grips were made by three drilling units equipped with milling heads: two of the “hydraulic cutter” type, model NR-10000M, and one of the “electric mill” type, model EM320M. Upon completion of drilling the next section of the trench, the bottom sludge was removed, the entire volume of the suspension in the trench was replaced by fresh clay solution by pumping, after which the reinforcement frame, spliced ​​from four integrally transportable sections 18 m high, was lowered into the trench, and laying of the concrete mixture began.
2. development of a cylindrical pit within the external fence with the subsequent construction of an internal reinforced concrete wall 2 m thick;
Under the protection of the fence, the soil was excavated with excavators to a depth of 61 m from sea level and an internal wall 2 m thick was erected, structurally combined with the fence.
3. laying a 4 m thick concrete pad and a 2.5 m thick structural bottom along the bottom of the pit;
A concrete pad 4 m thick was made of special concrete, and first its central part was laid by rolling the mixture with vibrating rollers, and then the annular peripheral part, working together with the enclosing wall, was concreted using conventional technology using submersible vibrators.
4. filling the cylindrical chamber with concrete;
The chamber space (with an internal diameter of 76.6 m and a height of 51 m), formed by a cylindrical fence and a bottom, was filled with a concrete mixture compacted by vibrating rollers. This technology minimizes the thermal stresses that develop during cement hydration. Like the cushion, the 1.5 m wide outer ring was concreted using traditional technology using deep vibrators.
5. concreting the structural outer slab 6 m thick;
After filling the chamber with concrete, a reinforced concrete top slab 6 m thick and 80.6 m in diameter was concreted in two steps (in semicircles). compaction) concrete mixture.

Thus, the various foundation elements of the Akashi-Kaike Bridge anchor abutment required concrete mixtures of several special formulations with a water-cement ratio ranging from 0.33 to 0.77 and a design concrete strength ranging from 9 to 37 MPa. The volume of concrete mixture was about 550 thousand m3. To handle this volume of work, a stationary concrete plant with a maximum technical capacity of 480 m3/h was equipped at the site.

The foundations of the pylons, supported on the bottom of the strait at a water depth of about 60 m, are massive steel-concrete cylinders, one of which, the larger one, has a diameter of 80 m and a height of 70 m, and the second, smaller one, is 78 and 67 m, respectively. The construction of each foundation included the following operations:
1. The development of weak sandy-gravelly bottom soil on an area with a diameter of 110 m to the design lower elevation of the foundation (-60 m from sea level) was carried out with a rope grab (four different types of grab buckets were used) from the Mitsutomo-1 process vessel. Quality control of the bottom layout was carried out using ultrasonic echolocation and unmanned video recording by a self-propelled underwater vehicle with remote control;

2. delivery of the steel shell of the foundation by towing afloat and its immersion by pouring water into the compartments of hollow walls 12 m thick, cleaning the soil surface within the central cavity of the shell from sludge, was carried out using 28 robotic machines with remote control;

3. stabilization of the bottom soil around the shell with a fill of gabions and boulders, within a radius of 80 m with a minimum layer thickness of 3 m;

4. Underwater concreting down to -10m below sea level within the central cavity was carried out in fourteen layers. The first layer was a cement-sand mortar, which ensured the required density of contact between the foundation and the bottom pebbles and filling the gaps under the walls of the shell. Subsequently, each layer of concrete mixture with a volume of 9 thousand m3 was laid continuously, on average in 51 hours with a productivity of 166 to 184 m3/h. This operation was carried out by 6 concrete pumps with the distribution of the mixture into 24 concrete pipes mounted in stationary extractors. The concrete mixture was supplied through an extensive network of concrete pipelines with a diameter of 200 mm using 18 spool mechanisms. Filling the compartments of the hollow walls of the shells from the level of -60 m to -5 m with concrete mixture was also carried out using the method of underwater concreting, while about 9 thousand m3 of concrete mixture was continuously laid. Each compartment contained 6 concrete pipes. The first layer, about 1.8 m thick, was also made of cement-sand mortar, which ensured the filling of the interface nodes of the metal structure stiffening elements located here. The order of concreting the compartments was determined based on considerations of the balance of the structure.

5. pumping water from the internal cavity and compartments of the shell and constructing a reinforced concrete upper tier of the foundation.
An independent free-standing 145 ton tower crane was used during the construction of the pylon.

Vibration dampers were attached to each pylon to reduce wind loads and reduce vibrations in the event of an earthquake. The cables were pulled by a guide rope, which was pulled by a helicopter.

The main cable, which has a sag of 1/10, was installed using prefabricated factory strands. The cable strand consists of factory-produced galvanized wires with a diameter of 5.23 mm in an amount of 127 pcs and a length of 4.085 m. High-strength wire with a tensile strength of 180 kg/mm2 was preferable to the standard one - 160 kg/mm2. Each strand was transported to the construction site where it was stretched from one anchorage above the saddle of each pylon to the opposite anchorage. This process was repeated 289 times for each main cable assembly.

By the way, if you stretch out all the steel threads (5.23 mm in diameter) of the supporting cables of the Akashi-Kaike Bridge, then they can encircle the globe more than seven times.

To produce a 1.12 m diameter cable, a special crimping machine was used to crimp 290 parallel wire strands. In the final stage, the cable hangers were attached to the main cable to support the main truss. The cable hangers were also factory produced with a diameter of 7mm, with a tensile strength of 180 kg/mm2, so the hanger used 2 high-tensile wires (instead of the usual 4) required to maintain the span buildings at farm nodes.
The steel for the truss joints was fabricated at the factory and delivered to the bridge by barge to the pylons, raised to the height of the roadway and delivered by an overhead crane to the appropriate location for connection to the support cable.

Some unique technologies were developed in the design and construction of this bridge. The designers were given a difficult goal to solve the problem of aerodynamic stability of the bridge. The controlling organization, the Honshu-Shikoku Bridge Authority, entered into an agreement with the Public Works Research Institute for the construction of the world's largest aerodynamic installation to test the full cross-section of the model in laminar and turbulent wind flows. As a result of the test, innovations were applied, such as: installation of vertical plates in the center of the lower part of the road, increasing the speed of vibrations.

The second unique technology used on the Akashi-Kaike Bridge was the use of parallel wire strands for the manufacture and installation of cables. The advantage of using the new method of spinning cables from parallel strands was their continuity from anchor to anchor, eliminating cable torsion and reducing potential accidents. Using the parallel strand method, a unique cable crimping machine was used that was designed to form the parallel strands into the final round shape. The use of high-tensile wire reduced the number of strands needed and the number of hangers in the rope to attach them to the truss, saving installation time and cost.

The bridge is illuminated by a total of 1,737 lights, 1,084 of which are on the main cables, 116 on the main towers, 404 on the beams and 132 on the fixtures. Three brightly illuminating gas discharge tubes of red, green and blue were installed on the main cables.

The bridge was built within 10 years. Despite the dangers of this type of construction, the careful safety measures have paid off, with several accidents resulting in 6 injuries but no fatalities, recording world class safety.

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