Great Seto Bridge

This is a very long bridge in Japan.

It goes over the sea and many small islands. Cars drive on the top part. Trains go on the bottom part. Before the bridge, people used boats. The boats took an hour to cross. Now, the trip takes only 20 minutes.

It is a big and helpful way to travel.

The Great Seto Bridge is a series of bridges in Japan.

It connects the islands of Honshu and Shikoku. The bridges cross the Seto Inland Sea. They also go over five small islands.

This bridge is special because it has two decks. The top deck is for cars. The bottom deck is for trains. It is the only route in its project to carry rail traffic. Before the bridge was built, people used ferries. The ferry trip took about one hour. Now, the trip takes only 20 minutes by car or train. Building the bridge took ten years. Work began in 1978 and ended in 1988. Workers used 705,000 tons of steel. They also used a lot of concrete. The Minami Bisan-Seto Bridge is the longest part. It is a suspension bridge. A suspension bridge uses long cables to hold up the road. This bridge is the 13th longest of its kind in the world. The bridge opened to the public on April 10, 1988.

The Great Seto Bridge is a massive series of bridges in Japan.

It connects the islands of Honshu and Shikoku across the Seto Inland Sea. The bridges also cross over five small islands along the way. This bridge system is very important for travel in the area. It is one of three routes in the Honshu-Shikoku Bridge Project. It is also the only route that carries trains.

The bridge works by using two different levels or decks. The upper deck is for cars on the Seto-Chuo Expressway. It has two lanes of traffic going in each direction. The lower deck holds one railway track in each direction. This part is called the Seto-Ohashi Line. The lower deck was even built to hold more tracks later. These extra tracks would be for a proposed Shinkansen line.

People have wanted a bridge here for a long time. In 1889, a man named Okubo spoke about uniting the provinces. He thought roads would help people communicate and travel better. The idea stayed quiet for about sixty years. In 1955, a sad accident happened when two ferries hit each other. This happened in thick fog near Takamatsu and killed 171 people. Because of this, leaders decided a safer bridge was needed.

Building the bridges was a huge job that took ten years.

Construction started in 1978 after an environmental report was ready. It cost about 7 billion US dollars to finish the work. Workers used 705,000 tons of steel and a lot of concrete. Even with safety ropes and nets, 17 workers died during the work. The bridge finally opened on April 10, 1988. Crown Prince Akihito opened it for cars and trains.

There are many different types of bridges in this long chain.

Some are suspension bridges that hang from large cables. Others are cable-stayed bridges or truss bridges. The Minami Bisan-Seto Bridge is the longest part of the whole system. It is the 13th longest suspension bridge span in the world. Before the bridge, a ferry trip took one hour. Now, the crossing takes only about 20 minutes.

The Great Seto Bridge is a massive series of double-deck bridges in Japan.

It connects the Okayama and Kagawa prefectures across the Seto Inland Sea. This bridge system spans five small islands to link the islands of Honshū and Shikoku. It is a vital part of the Honshū–Shikoku Bridge Project. This project includes three different routes connecting the two main islands. The Great Seto Bridge is unique because it is the only route that carries rail traffic.

The structure functions using a double-deck design to separate different types of transport. The upper deck carries the Seto-Chūō Expressway. This highway provides two lanes of traffic for vehicles in each direction. The lower deck carries the Seto-Ōhashi Line, which is a railway. This lower level has one railway track for trains traveling in each direction. Engineers specifically designed the lower deck to accommodate more tracks in the future. They intended to add extra Shinkansen tracks for a proposed Shikoku Shinkansen line.

The bridge system is actually made of several different types of bridges. Six of these are specifically named, while the other five are viaducts. The Shimotsui-Seto Bridge is a double-decked suspension bridge. It is the northernmost part of the Seto-Chūō Expressway. Next are the Hitsuishijima and Iwakurojima Bridges. These are both double-decked cable-stayed bridges with identical designs. The Yoshima Bridge is a continuous double-decked truss bridge. Finally, the Kita Bisan-Seto and Minami Bisan-Seto Bridges are both large suspension bridges.

The idea for a bridge across this sea existed for over a century. In 1889, a member of the Prefectural Parliament named Ōkubo spoke about uniting the provinces. He believed roads would help the islands enjoy better transportation and communication. This vision remained dormant for about sixty years. In 1955, a tragic event changed the priority of the project. Two ferries collided in dense fog near the coast of Takamatsu. This accident killed 171 people, including 100 students on school trips. This disaster made a safer crossing through a bridge seem necessary.

Construction of the bridges was a massive engineering undertaking. It began in 1978 after an Environment Assessment Report was published. The project was delayed for five years by the 1973 oil shock. Building the system took ten years and cost US$7 billion. Workers used 705,000 tons of steel and large amounts of concrete. Despite using safety measures like nets and ropes, 17 workers died during construction. The bridges officially opened to road and rail traffic on April 10, 1988. Crown Prince Akihito performed the opening ceremony.

Several parts of the bridge hold impressive global records. The Minami Bisan-Seto Bridge is the longest span in the entire system. It is the 13th longest suspension bridge span in the world. The Kita Bisan-Seto Bridge is also significant. It is the 19th largest suspension bridge in the world. The Shimotsui-Seto Bridge is the 45th largest suspension bridge globally. At the time of the opening, the one-way toll to cross was ¥6300.

The bridge has greatly improved how people move through the region. Before the bridges were built, people used ferries to cross the sea. A ferry crossing took about one hour to complete. Now, the trip across the Great Seto Bridge takes about 20 minutes by car or train. This connection links the major islands of Japan more efficiently. It also serves as a model for other large-scale infrastructure projects. The bridge is even recognized as a "Sister Bridge" to the Golden Gate Bridge in San Francisco.