is a

railroad Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in railway track, tracks, which usually consist of two parallel steel railway track, rails. Rail transport is one of the two primary means of ...

tunnel A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is usually completely enclosed except for the two portals common at each end, though there may be access and ve ...

Shizuoka Prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu. Shizuoka Prefecture has a population of 3,555,818 and has a geographic area of . Shizuoka Prefecture borders Kanagawa Prefecture to the east, Yamanashi Pref ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

operated by

JR Central is the main railway company operating in the Chūbu (Nagoya) region of central Japan. It is officially abbreviated in English as JR Central and occasionally as JR Tokai (). The term ''Tōkai'' refers to the southern portion of Central Japan, ...

’s

Tōkaidō Main Line The Tōkaidō Main Line () is one of the most important railway corridors in Japan, connecting the major cities of Tokyo and Kobe via Shizuoka (city), Shizuoka, Nagoya, Kyoto and Osaka. The line, with termini at Tokyo Station, Tokyo and Kōbe St ...

. This 7.8 km long tunnel shortened the trunk route between

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

and

Kobe Kobe ( ; , ), officially , is the capital city of Hyōgo Prefecture, Japan. With a population of around 1.5 million, Kobe is Japan's List of Japanese cities by population, seventh-largest city and the third-largest port city after Port of Toky ...

by omitting a detour round the mountains between

Atami is a city located in Shizuoka Prefecture, Japan. , the city had an estimated population of 36,865 in 21,593 households

and

Numazu is a city located in eastern Shizuoka Prefecture, Japan. , the city had an estimated population of 189,486 in 91,986 households, and a population density of 1,014 persons per km2. The total area of the city is . Geography Numazu is at the n ...

History

The initial routing of the Tōkaidō Main Line railway, connecting Tokyo with

Osaka is a Cities designated by government ordinance of Japan, designated city in the Kansai region of Honshu in Japan. It is the capital of and most populous city in Osaka Prefecture, and the List of cities in Japan, third-most populous city in J ...

, avoided the

Hakone is a List of towns in Japan, town in Kanagawa Prefecture, Japan. , the town had a population of 10,965, and total area of . Hakone is a notable spa town and a popular tourist destination due to its many onsen, hot springs being within view of ...

mountains between Shizuoka and

Kanagawa Prefecture is a Prefectures of Japan, prefecture of Japan located in the Kantō region of Honshu. Kanagawa Prefecture is the List of Japanese prefectures by population, second-most populous prefecture of Japan at 9,221,129 (1 April 2022) and third-dens ...

s by taking a long detour north to

Gotemba is a city on the southeastern flank of Mount Fuji in Shizuoka Prefecture, Japan. , the city had an estimated population of 88,370 in 36,096 households, and a population density of 450 persons per km². The total area of the city is . Geography ...

and then south to Numazu. This route is now known as the

Gotemba Line The is a railway line in Japan operated by the Central Japan Railway Company (JR Central). It connects Kōzu Station (Kanagawa), Kōzu Station in Odawara, Kanagawa, Odawara to Numazu Station, Numazu via Gotemba Station, Gotemba. The ''Mt. Fuj ...

, and it follows the same path as the

Tōmei Expressway The is a national expressway on the island of Honshū in Japan. It is operated by Central Nippon Expressway Company. The expressway is designated as E1 under the "2016 Proposal for Realization of Expressway Numbering", because it parallels Na ...

to this day. Recognizing that the Gotemba loop created a significant bottleneck in the rail system, the Japanese

Railroad Ministry Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in tracks, which usually consist of two parallel steel rails. Rail transport is one of the two primary means of land transport, next to road ...

issued a contract in 1918 to the

Kajima Corporation is one of the oldest and largest construction companies in Japan. Founded in 1840, the company has its headquarters in Motoakasaka, Minato, Tokyo. The company is known for its DIB-200 proposal. The company stock is traded on four leading Japa ...

to build a tunnel through the Hakone mountains. The project was promoted as a major

public works Public works are a broad category of infrastructure projects, financed and procured by a government body for recreational, employment, and health and safety uses in the greater community. They include public buildings ( municipal buildings, ...

initiative intended to help boost Japan’s economy following the post-

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

economic recession An economy is an area of the Production (economics), production, Distribution (economics), distribution and trade, as well as Consumption (economics), consumption of Goods (economics), goods and Service (economics), services. In general, it is ...

. However, the construction of the 7,804-meter tunnel proved extremely challenging due to numerous unforeseen issues with the local

geology Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...

and contemporary tunneling technology. The Hakone mountain range is an active volcanic zone, containing a number of faults and frequently experiencing

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

s. In addition, workers faced problems with significant water seepage, soft rock formations, and hot spring water vents. On April 1, 1920, a large section of the tunnel collapsed from the Atami side, trapping 42 workers. Despite heroic efforts to rescue them, only 17 workers were saved a week later. The tunnel was also damaged during the

Great Kantō earthquake Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" * Artel Great (bo ...

, although no fatalities occurred. Another collapse took place on February 26, 1930, during an earthquake, resulting in the deaths of five more workers. The project took far longer and cost much more than originally anticipated, with a total of 67 workers losing their lives during construction. The two ends of the tunnel were joined on June 19, 1933, and the Tanna Tunnel opened to rail traffic on March 10, 1934. At the time of its completion, it was Japan’s second-longest tunnel, only surpassed by the Shimizu Tunnel once it was finished. The story of the construction of the Tanna Tunnel was the subject of a stage play by Hideji Hōjō in 1942. The Tanna Tunnel remains in operation on the Tōkaidō Main Line to this day. Traffic on the

Tōkaidō Shinkansen The is a Japanese high-speed rail line that is part of the nationwide Shinkansen network. Along with the San'yō Shinkansen, it forms a continuous high-speed railway through the Taiheiyō Belt, also known as the Tokaido corridor. Opening in 19 ...

uses the parallel Shin-Tanna Tunnel (7,950m) completed in 1963.

References

External links

{{Commonscat, Tanna Tunnel
Kajima Corporation home page
Railway tunnels in Japan Rail transport in Shizuoka Prefecture Tunnels completed in 1934 1934 establishments in Japan Tunnels in Shizuoka Prefecture