The
Seikan Tunnel (青函トンネル
Seikan Tonneru or 青函隧道
Seikan Zuidō) is a railway
tunnelA tunnel is an underground passageway. The definition of what constitutes a tunnel is not universally agreed upon. However, in general tunnels are at least twice as long as they are wide. In addition, they should be completely enclosed on all sides, save for the openings at each end...
in
Japanis an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, with a long portion under the seabed. It is the longest undersea tunnel in the world, although the
Channel TunnelThe Channel Tunnel , also known as the Chunnel, is a undersea rail tunnel linking Folkestone, Kent in the UK with Coquelles, near Calais in northern France beneath the English Channel at the Strait of Dover. At its lowest point it is deep...
between the United Kingdom and France has a longer under-sea portion. It travels beneath the
Tsugaru Straitis a channel between Honshū and Hokkaidō in northern Japan connecting the Sea of Japan with the Pacific Ocean. It was named after the western part of Aomori Prefecture...
— connecting
Aomori Prefectureis a prefecture of Japan located in the Tōhoku Region. The capital is the city of Aomori.- History :The Aomori Prefecture came into existence in 1871. Aomori Town was established in 1889. The town was incorporated as a city in 1898 with a population of 28,000....
on the Japanese island of
Honshūor Honshu is the largest island of Japan. The nation's main island, it is south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Strait...
and the island of
Hokkaidō, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island and the largest, northernmost of its 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaidō from Honshū, although the two islands are connected by the underwater Seikan Tunnel...
— as part of the
Kaikyo Lineis an 87.8-kilometre railway line operated mainly by the Hokkaido Railway Company. The line runs from Naka-Oguni Station in Sotogahama, Aomori, through the Seikan Tunnel between Honshū and Hokkaidō, and on to Kikonai Station in Kikonai, Hokkaidō...
of
Hokkaido Railway CompanyThe is one of the constituent companies of Japan Railways Group , and thus often known as . It operates intercity rail services in Hokkaidō, Japan. The company will introduce Kitaca, a smart card ticketing system, from autumn 2008....
. Although it is the longest traffic (railway or road) tunnel in the world, faster and cheaper air travel has left the Seikan Tunnel comparatively underused. Its claim to the record for the longest tunnel will be taken when the
Gotthard Base TunnelThe Gotthard Base Tunnel is a railway tunnel under construction in Switzerland. With a planned length of and a total of of tunnels, shafts and passages planned, it will be the longest tunnel in the world upon completion, ahead of the current record holder, the Seikan Tunnel...
, a European railway tunnel, is completed in around 2018. It is also the deepest rail tunnel in the
world.
History
Connecting the islands of
Honshūor Honshu is the largest island of Japan. The nation's main island, it is south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Strait...
and
Hokkaidō, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island and the largest, northernmost of its 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaidō from Honshū, although the two islands are connected by the underwater Seikan Tunnel...
by a fixed link had been considered since the
Taishō periodThe , or Taishō era, is a period in the history of Japan dating from July 30, 1912 to December 25, 1926, coinciding with the reign of the Taishō Emperor. The health of the new emperor was weak, which prompted the shift in political power from the old oligarchic group of elder statesmen to the Diet...
(1912–1925), but serious survey only commenced in 1946, due to the loss of overseas territory at the end of World War II and the need to accommodate returnees. In 1954, five ferries, including the
Toya MaruThe was a Japanese train ferry constructed by the Japanese National Railways which sank during a typhoon in the Tsugaru Strait between the Japanese islands of Hokkaidō and Honshū on September 26, 1954...
, sank in the Tsugaru Strait during a typhoon, killing 1,430 passengers. The following year the
Japanese National Railways (JNR), abbreviated or "JNR", was the national railway network of Japan from 1949 to 1987.-History:The term Kokuyū Tetsudō "state-owned railway" originally referred to a network of railway lines operated by nationalized companies under the control of the Railway Institute following the nationalization...
expedited the tunnel investigation.
| Timeline |
| 1946-04-24 |
Geological surveying begun |
| 1954-09-26 |
Train ferry Toya MaruThe was a Japanese train ferry constructed by the Japanese National Railways which sank during a typhoon in the Tsugaru Strait between the Japanese islands of Hokkaidō and Honshū on September 26, 1954...
sank
in the Tsugaru Strait |
| 1964-03-23 |
Japan Railway Construction
Public Corporation established |
| 1971-09-28 |
Main tunnel construction begun |
| 1983-01-27 |
Pilot tunnel holed through |
| 1985-03-10 |
Main tunnel holed through |
| 1988-03-13 |
Tunnel opened |
Also of concern was the increasing traffic between the two islands. A booming economy saw traffic levels on the JNR-operated Seikan (a contraction of principal cities
Aomoriis the capital city of Aomori Prefecture, in Japan. The city faces the Tsugaru Strait via Mutsu Bay to the North and the Hakkōda Mountains to the South. It has the biggest seaport in the prefecture...
and
Hakodateis a city and port located in Oshima, Hokkaidō, Japan. It is the capital city of Oshima Subprefecture.As of March 2008, the city has an estimated population of 287,691 and a density of 442.24 persons per km²...
) Ferry doubled to 4,040,000 persons/year from 1955 to 1965, and cargo levels rose 1.7 times to 6,240,000 tonnes/year. In 1971, traffic forecasts predicted increasing growth that would outstrip the ability of the ferry pier facility, which was constrained by geographical conditions. In September 1971, the decision was made to commence work on the tunnel. A
ShinkansenThe is a network of high-speed railway lines in Japan operated by four Japan Railways Group companies. Starting with the Tōkaidō Shinkansen in 1964, the now long network has expanded to link most major cities on the islands of Honshū and Kyūshū at speeds up to...
-capable cross section was selected, with plans to extend the Shinkansen network.
Arduous construction in difficult geological conditions proceeded. 34 workers were killed during construction.
On 27 January 1983, Japanese Prime Minister
Yasuhiro NakasoneYasuhiro Nakasone is a Japanese politician who served as Prime Minister of Japan from November 27, 1982 to November 6, 1987...
pressed a switch that set off a blast that completed the pilot tunnel. Similarly on 10 March 1985, Minister of Transport Tokuo Yamashita symbolically holed through the main tunnel.
The project's success was questioned at the time, with the 1971 traffic predictions being overestimates. Instead of the traffic rate increasing as predicted to a peak in 1985, it peaked earlier in 1978 and then proceeded to decrease. The decrease was attributed to the slowdown in Japan's economy since the first oil crisis in 1973, and to advances made in air transport facilities and longer-range sea transport.
The tunnel was opened on 13 March 1988, having cost a total of ¥538.4 billion (US$3.6 billion) to construct.
Once the tunnel was completed, all railway transport between Honshū and Hokkaidō used the tunnel. However, for passenger transport, 90% of people use air due to the speed and cost. For example, to travel between
Tokyo, officially , is one of the 47 prefectures of Japan and is located on the eastern side of the main island Honshū. The twenty-three special wards of Tokyo, each governed as a city, cover the area that was once the city of Tokyo in the eastern part of the prefecture, totaling over 8 million people....
and Sapporo by train takes more than ten hours and thirty minutes, with several transfers. By air, the journey is three hours and thirty minutes, including airport access times. Deregulation and competition in Japanese domestic air travel has brought down prices on the Tokyo-Sapporo route, making rail more expensive in comparison.
The
HokutoseiThe is a limited express sleeping car train service in Japan operated jointly by East Japan Railway Company and Hokkaido Railway Company .-Service description:...
overnight train service, which began service after the completion of the Seikan Tunnel, is still popular among travellers. The newer and more luxurious
CassiopeiaThe is a luxury overnight limited express train service in Japan operated by East Japan Railway Company . It runs between Ueno Station in Tokyo and the city of Sapporo in the northern island of Hokkaidō. The one-way journey lasts approximately 16½ hours.Going from Ueno to Sapporo, trains call...
overnight train service is frequently fully booked.
ShinkansenThe is a network of high-speed railway lines in Japan operated by four Japan Railways Group companies. Starting with the Tōkaidō Shinkansen in 1964, the now long network has expanded to link most major cities on the islands of Honshū and Kyūshū at speeds up to...
trains currently do not run through the tunnel, although the Seikan Tunnel was built to accommodate Shinkansen trains. The JR East company decided to extend the
Tohoku ShinkansenThe is a Japanese high-speed Shinkansen rail line, connecting Tokyo with Hachinohe in Aomori Prefecture for a total length of 593 km, Japan's longest Shinkansen line. It runs through the more sparsely populated Tōhoku region of Japan's main island Honshū. It has two spur lines, Yamagata...
to
AomoriAomori may refer to:* Aomori Prefecture, Japan** Aomori, Aomori, the capital of Aomori Prefecture* Aomori , a novel by Dazai Osamu* the Aomori meteorite of 1984, which fell in Tohoku, Japan...
and then to make connections to the future
Hokkaido ShinkansenThe Hokkaidō Shinkansen is a high-speed rail line currently under construction between Aomori and Hokkaidō through the Seikan Tunnel. Construction started in May 2005, and the initial Shin-Aomori to Shin-Hakodate section is projected to open in 2015. There are long-term plans to extend the line...
line. From Aomori, the Hokkaido Shinkansen would continue on to Shin-Hakodate Station in Hakodate,
Hokkaido, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island and the largest, northernmost of its 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaidō from Honshū, although the two islands are connected by the underwater Seikan Tunnel...
by 2015 and then eventually to
Sapporo Stationis a train station located in Kita-ku and Chūō-ku, Sapporo, Hokkaidō, Japan. It is served by Hakodate Main Line and other lines of Hokkaidō Railway Company and is also connected to Sapporo Subway. The Hokkaidō Railway Company part is in Kita-ku while the Sapporo Subway part is in Chūō-ku.Sapporo...
. The future Hokkaido Shinkansen would be operated by JR Hokkaido.
Surveying, construction and geology
| Tsugaru Strait traffic data |
| Year | Passengers
(persons/yr) | Freight (T/yr) | Mode |
|---|
| 1955 |
2,020,000 |
3,700,000 |
Seikan Ferry |
| 1965 |
4,040,000 |
6,240,000 |
Seikan Ferry |
| 1970 |
9,360,000 |
8,470,000 |
Seikan Ferry |
| 1985 |
9,000,000[This may be a typographical error in the source] |
17,000,000 |
1971 Forecast |
| 1988 |
~3,100,000 |
— |
Seikan Tunnel |
| 1999 |
~1,700,000 |
— |
Seikan Tunnel |
| 2001 |
— |
>5,000,000 |
Seikan Tunnel |
| † |
Surveying started in 1946 and in 1971, twenty-five years later, construction began. By August 1982, less than 700 metres of the tunnel remained to be excavated. First contact between the two sides was in 1983.
The
Tsugaru Straitis a channel between Honshū and Hokkaidō in northern Japan connecting the Sea of Japan with the Pacific Ocean. It was named after the western part of Aomori Prefecture...
has eastern and western necks, both approximately 20 kilometres across. Initial surveys undertaken in 1946 indicated that the eastern neck was up to 200 metres deep with volcanic geology. The western neck had a maximum depth of 140 metres and geology consisting mostly of sedimentary rocks of the Neogene period. The western neck was selected, with its conditions considered favourable for tunnelling.
Geology of the undersea portion of the tunnel consists of volcanic rock,
pyroclastic rockPyroclastic rocks or pyroclastics are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic...
, and sedimentary rock of the late
TertiaryThe Tertiary is a term for a geologic period 65 million to 2.588 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...
era. The area is folded into a nearly vertical
anticlineIn structural geology, an anticline is a fold that is convex up and has its oldest beds at its core. The term is not to be confused with antiform, which is a purely descriptive term for any fold that is convex up. Therefore if age relationships In structural geology, an anticline is a fold that is...
, which means that the youngest rock is in the centre of the Strait, and encountered last. Divided roughly into thirds, the Honshū side consists of volcanic rocks (andesite, basalt etc); the Hokkaidō side consists of sedimentary rocks (Tertiary period
tuffTuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. - Volcanic ash :The products of a volcanic eruption are...
,
mudstoneMudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
, etc); and the centre portion consists of Kuromatsunai
strataIn geology and related fields, a stratum is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. Each layer is generally one of a number of parallel layers that lie one upon another, laid down by natural forces. They may extend over...
(Tertiary period sand-like mudstone). Igneous intrusions and faults caused crushing of the rock and complicated the tunnelling procedures.
Initial geological investigation occurred from 1946–1963 which involved drilling the sea-bed,
sonic surveysEcho sounding is the technique of using sound pulses directed from the surface or from a submarine vertically down to measure the distance to the bottom by means of sound waves. Echo sounding can also refer to hydroacoustic "echo sounders" defined as active sound in water used to study fish...
, submarine boring, observations using a mini-submarine, and seismic and magnetic surveys. To establish a greater understanding, a horizontal pilot boring was undertaken along the line of both the service and pilot tunnels.
Tunnelling occurred simultaneously from both the northern and southern ends. The dry land portions were tackled with traditional mountain tunnelling techniques, with a single main tunnel. However, for the 23.3-kilometre undersea portion, three bores were excavated with increasing diameters respectively: an initial pilot tunnel, a service tunnel, and finally the main tunnel. The service tunnel was periodically connected to the main tunnel with a series of connecting shafts, at 600- to 1,000-metre intervals. The pilot tunnel serves as the service tunnel for the central five-kilometre portion.
Beneath the Tsugaru Strait, the use of a
tunnel boring machineA tunnel boring machine is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. They can bore through hard rock, sand, and almost anything in between. Tunnel diameters can range from a metre to almost 16 metres to date...
(TBM) was abandoned after less than two kilometres owing to the variable nature of the rock and difficulty in accessing the face for advanced grouting. Blasting with dynamite and mechanical picking were then used to excavate.
Maintenance
A 2002 report by Michitsugu Ikuma described, for the undersea section, that "
the tunnel structure appears to remain in a good condition". The amount of inflow has been decreasing with time, although it "
increases right after a large earthquake".
Structure
Originally only narrow gauge track was laid through the tunnel, but in 2005 the
Hokkaidō ShinkansenThe Hokkaidō Shinkansen is a high-speed rail line currently under construction between Aomori and Hokkaidō through the Seikan Tunnel. Construction started in May 2005, and the initial Shin-Aomori to Shin-Hakodate section is projected to open in 2015. There are long-term plans to extend the line...
project started construction has included laying dual-gauge track and linking the tunnel into the
ShinkansenThe is a network of high-speed railway lines in Japan operated by four Japan Railways Group companies. Starting with the Tōkaidō Shinkansen in 1964, the now long network has expanded to link most major cities on the islands of Honshū and Kyūshū at speeds up to...
network. Shinkansen trains will be able to traverse the tunnel to Hakodate from 2015 and eventually Sapporo. The tunnel has 52 kilometres of continuous welded rail.
Two stations are located within the tunnel itself:
Tappi-Kaitei Stationis a train station within the Seikan Tunnel on the Kaikyo Line in Sotogahama, Aomori, Japan. It is operated by Hokkaido Railway Company.Tappi-Kaitei is very infrequently serviced by JR trains , but is connected by an underground cable car to the surface...
and
Yoshioka-Kaitei Stationis a train station within the Seikan Tunnel on the Kaikyo Line in Fukushima, Hokkaidō, Japan. It is operated by Hokkaido Railway Company. The station is located 149.5 metres below sea level, making it the deepest underground station in Japan....
. The stations serve as emergency escape points. In the event of a fire or other disaster, both stations provide the equivalent safety of a much shorter tunnel. The effectiveness of the escape shafts located at the emergency stations is enhanced by having exhaust fans to extract smoke, television cameras to help route passengers to safety, thermal (infrared) fire alarm systems and water spray nozzles.
Previously, both the stations contained museums detailing the history and function of the tunnel and which could be visited on special sightseeing tours. Only Tappi-Kaitei remains as a museum, Yoshioka-Kaitei having been demolished on 16 March 2006 to make way for
Hokkaidō ShinkansenThe Hokkaidō Shinkansen is a high-speed rail line currently under construction between Aomori and Hokkaidō through the Seikan Tunnel. Construction started in May 2005, and the initial Shin-Aomori to Shin-Hakodate section is projected to open in 2015. There are long-term plans to extend the line...
preparations.
The two stations were the first train stations in the world built under the sea.
See also
- Channel Tunnel
The Channel Tunnel , also known as the Chunnel, is a undersea rail tunnel linking Folkestone, Kent in the UK with Coquelles, near Calais in northern France beneath the English Channel at the Strait of Dover. At its lowest point it is deep...
, an undersea railway tunnel connecting Great BritainGreat Britain is an island lying to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island. With a population of about 59.6 million people, it is the third most populated island on Earth. Great Britain is surrounded by over 1000 smaller...
and FranceFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
.
- Seikan Tunnel Tappi Shako Line
The is a Japanese funicular line in Sotogahama, Aomori, operated by Seikan Tunnel Museum. The line descends from the museum near into an underground station on the Seikan Tunnel, the longest railway tunnel in the world...
- Train on Train
is the name given to the concept currently being developed by Hokkaidō Railway Company in Japan as a means of transporting freight at higher speeds through the Seikan Tunnel when Hokkaidō Shinkansen high-speed passenger services through the tunnel commence in 2015.-Overview:When the Hokkaidō...
, an experimental concept for conveying freight at higher speeds through the tunnel
External links
- The Seikan Tunnel, Aomori Prefecture Government, version of 3 May 2006 at the Internet Archive
The Internet Archive is a nonprofit organization dedicated to building and maintaining a free and openly accessible online digital library, including an archive of the World Wide Web....