Amarube Viaduct
Encyclopedia
The is a railway bridge in the town of Kami
Kami, Hyogo (Mikata)
is a town located in Mikata District, Hyōgo, Japan. The town was formed on April 1, 2005 from the merger of the former town of Kasumi, from Kinosaki District, and the towns of Mikata and Muraoka, both from Mikata District....

, Mikata District
Mikata District, Hyogo
Mikata is a district located in Hyōgo, Japan.As of the April 1, 2005 merger , the district has an estimated population of 40,084 and a density of 66 persons per km²...

, Hyōgo Prefecture
Hyogo Prefecture
is a prefecture of Japan located in the Kansai region on Honshū island. The capital is Kobe.The prefecture's name was previously alternately spelled as Hiogo.- History :...

, on JR West
West Japan Railway Company
, also referred to as , is one of the Japan Railways Group companies and operates in western Honshū. It has its headquarters in Kita-ku, Osaka.-History:...

's San'in Main Line
San'in Main Line
The is a railway line in western Japan that runs from Kyoto to Shimonoseki, Yamaguchi Prefecture, operated by West Japan Railway Company . It is the major railway line of the San'in region, running along the Japan Sea, crossing Kyoto, Hyōgo, Tottori, Shimane and Yamaguchi prefectures...

 between the stations of Yoroi
Yoroi Station
is a station in Kami, Mikata District, Hyōgo, Japan-Adjacent stations:...

 and Amarube
Amarube Station
is a station in Kami, Mikata District, Hyōgo, Japan-Adjacent stations:...

.

Background

Work began on the bridge in December 1909, and it opened for service March 1, 1912. It is 310.59 meters in length and 41.45 meters tall. Construction cost a total of 331,535 yen. It had 11 vertical supports and 23 sections of girders. National Route 178
Route 178 (Japan)
National Route 178 is a national highway of Japan connecting Maizuru, Kyoto and Iwami, Tottori in Japan, with a total length of 201 km ....

 passes beneath it. The structure's unique design and bright color made it popular not only with rail fans but tourists as well. The closest station is Amarube Station
Amarube Station
is a station in Kami, Mikata District, Hyōgo, Japan-Adjacent stations:...

, and the mountain behind it provides a popular point from which photographers take pictures of the bridge. From March 6, 2008, the bridge was closed periodically for the construction of its replacement.

Construction

The terrain along the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...

 coast is very rugged between the towns of Kami
Kami, Hyogo (Mikata)
is a town located in Mikata District, Hyōgo, Japan. The town was formed on April 1, 2005 from the merger of the former town of Kasumi, from Kinosaki District, and the towns of Mikata and Muraoka, both from Mikata District....

 and Shin'onsen, and it was necessary to lay the railbed amongst the mountains. However, due to the area's topography, it would also have to cross over villages between mountains. Finally, using large embankments and paths paralleling National Route 178, a route was chosen. Although there was a plan for a concrete structure, it was dismissed as impractical, and an American engineer's opinion was sought. Taking that into consideration, Ministry of Railways
Japanese Government Railways
The Japanese Government Railways was the national railway system directly operated by the central government of Japan until 1949. It is a predecessor of Japanese National Railways and the Japan Railways Group.- Name :...

 engineer Furukawa decided that it would be a trestle bridge. The steel for the piers was imported from the American Bridge Company's Pencoyd Iron Works via Kyūshū
Kyushu
is the third largest island of Japan and most southwesterly of its four main islands. Its alternate ancient names include , , and . The historical regional name is referred to Kyushu and its surrounding islands....

, and arrived in August 1910. Girders were made by Ishikawajima Shipworks (now IHI Corporation), and were sent from Kōbe in September 1911. Upon completion, its cost exceeded 330,000 yen and more than 250,000 people had worked on the project. Because of the tremendous danger involved with its construction, workers were covered by a 20,000 yen insurance plan.

This bridge was the San'in Main Line
San'in Main Line
The is a railway line in western Japan that runs from Kyoto to Shimonoseki, Yamaguchi Prefecture, operated by West Japan Railway Company . It is the major railway line of the San'in region, running along the Japan Sea, crossing Kyoto, Hyōgo, Tottori, Shimane and Yamaguchi prefectures...

's most difficult project after the Tokan Tunnel, one end of which begins at the bridge's east end. Following the structure's completion, it became possible to travel all the way from Kyōto
Kyoto
is a city in the central part of the island of Honshū, Japan. It has a population close to 1.5 million. Formerly the imperial capital of Japan, it is now the capital of Kyoto Prefecture, as well as a major part of the Osaka-Kobe-Kyoto metropolitan area.-History:...

 to Izumo
Izumo, Shimane
is a city located in Shimane, Japan. Izumo is known for Izumo soba noodles and the Izumo Taisha Shinto shrine.-Demographics:The modern city was founded on November 3, 1941....

. Over 90 years after its completion, it remains Japan's largest railway trestle and has great historical value as an early railway structure.

Accident

On December 28, 1986 around 1:25 pm, an out-of-service Miyabi train traveling from Kasumi Station was caught by strong winds from the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...

, and all seven passenger cars of the train fell from the bridge, with only a few bogies remaining on the tracks. The locomotive's weight prevented its derailment. The cars fell directly below, landing on a fish-processing plant. Five women working at the plant and the train's conductor died in the accident. Five others in the plant and one food-service worker aboard the train were seriously injured.

This was the first disaster since the opening of the bridge. The accident is attributed to human error. Although the 25 m/s winds activated warning devices, the train proceeded across the bridge.

Following the accident, Japan National Railways reviewed their policies and decided to stop train operations when wind speeds exceeded 20 m/s. Their guidelines for switching to substitute bus service became more stringent. A cenotaph
Cenotaph
A cenotaph is an "empty tomb" or a monument erected in honour of a person or group of people whose remains are elsewhere. It can also be the initial tomb for a person who has since been interred elsewhere. The word derives from the Greek κενοτάφιον = kenotaphion...

 was put in place on November 23, 1988, and on December 28 of each year a Buddhist service is held.

Maintenance

To protect the bridge's piers from the salt air, the structure is repainted every few years. Although the bridge is being replaced, this work was carried out as recently as 2007.

Debate

Plans for bridge's replacement have been studied since the 1970s, however for financial reasons it was always decided that the original structure would continue to be maintained. Due to the aging of the bridge, and in order to ensure the punctuality of trains, the prefectural governments of Tottori and Hyōgo with local municipalities organized and decided to proceed with the bridge's replacement. Following the accident of December 28, 1986, delays and cancellations increased, but the main reason for the delays is the increased frequency of service east of Kinosaki Onsen Station, and the operational problems caused by the line's single-track construction. Although the bridge is sometimes closed, it was not a strong influence on the decision. A new prestressed concrete
Prestressed concrete
Prestressed concrete is a method for overcoming concrete's natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete...

 bridge on the existing structure's south side will be built to allow trains to operate in wind conditions of up to 30 m/s. Its design will allow for easy maintenance, and because local governments are providing 80% of the cost, JR West plans to complete the work as quickly as possible. Work has been underway since Spring 2007.

Sightseers and railfans have voiced regret over the replacement of the bridge, and many believe that the new concrete bridge will not be a draw for tourists. During 2006 and 2007, prior to the construction, the surrounding area was inundated with people hoping to see the bridge one last time. Some trespassed on private property, and the unusually large number of visitors proved troublesome for local residents.

The Tottori Prefectural Assembly has announced that they may withhold funding for the work if the overnight express service Izumo is discontinued.

There are plans for the bridge following the completion of its replacement. Some call for the preservation of the structure, others for the construction of a memorial hall. The local government is forming a committee to consider the matter. It has been requested that in any case that the bridge's physical prominence and the 1986 accident will be commemorated for future generations. One plan put forth by the government of Kami preserves the three vertical supports and girders closest to Amarube Station.

On May 27, 2007, the ceremony marking the beginning of construction was held. It was attended by the governor of Hyōgo Prefecture as well as members of the Diet
Diet of Japan
The is Japan's bicameral legislature. It is composed of a lower house, called the House of Representatives, and an upper house, called the House of Councillors. Both houses of the Diet are directly elected under a parallel voting system. In addition to passing laws, the Diet is formally...

. Even after construction began, regular maintenance was still carried out on the bridge. The presence of construction vehicles detracts from the location's appeal to tourists, and the number of visitors has decreased. With the completion of maintenance in October 2007, scaffolding was dismantled and stored in what was previously a parking lot for tourists. The parking lot has been moved to a location nearby.

Work began in earnest in October 2008, and both the observation area at the station and the station itself were closed for safety purposes.

Construction timeline

  • November 2001 - the decision is made to construct a new bridge.
  • October 2003 - prestressed concrete
    Prestressed concrete
    Prestressed concrete is a method for overcoming concrete's natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete...

     is chosen as the new structure's material.*March 2005 - it is decided that the bridge will be a rigid frame bridge.
  • March 2006 - the Hyōgo, Tottori
    Tottori Prefecture
    is a prefecture of Japan located in the Chūgoku region. The capital is the city of Tottori. It is the least populous prefecture in Japan.- History :Before the Meiji Restoration, Tottori encompassed the old provinces of Hōki and Inaba...

    , and local governments and JR West come to a basic agreement about the bridge.
  • November 21, 2006 - JR West runs an express Amarube service between Himeji
    Himeji Station
    on the West Japan Railway Company is located in the heart of Himeji, Japan. Himeji is a major stop on the Sanyō Main Line, and the western end of the JR Kobe Line...

     and Hamasaka
    Hamasaka Station
    is a station in Shin'onsen, Mikata District, Hyōgo, Japan-Adjacent stations:...

    . The nationwide "Bridge Summit" is held in the town of Kasumi.
  • March 24 through April 1, 2007 - special train Omoide no Amarube is run between Toyooka
    Toyooka Station
    Toyooka Station is the name of two train stations in Japan:# Toyooka Station # Toyooka Station...

     and Hamasaka.
  • March 29, 2007 - construction begins. Main companies are Shimizu Corporation
    Shimizu Corporation
    is a leading architectural, engineering and general contracting firm, offering an integrated, comprehensive planning, design and build solutions for a broad range of construction and engineering projects worldwide...

     and Zenitaka Corporation. Total cost is estimated to be 3 billion yen. It will be an extradosed bridge
    Extradosed bridge
    An extradosed bridge employs a structure that is frequently described as a cross between a girder bridge and a cable-stayed bridge. The name comes from the French word extradossé, which is derived from the word extrados. Extrados is defined as the exterior curve of an arch.This description is...

    .
  • 2010 - planned completion.
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