Wartime Bullet Train Project: Construction and Suspension

After the outbreak of the Sino-Japanese War, passenger and freight traffic between the Japanese home islands and Korea, Manchuria and China grew sharply, and the Tokaido and Sanyo main lines approached the limit of their capacity. The Ministry of Railways set up an internal study committee at the end of 1938 and, in July 1939, a Trunk Line Investigation Council established by imperial ordinance formally adopted the Dangan Ressha Keikaku (弾丸列車計画, Bullet Train Plan): a new standard-gauge (1,435 mm) line of about 984 km from Tokyo to Shimonoseki, with a target top speed of 200 km/h, Tokyo to Osaka in about four and a half hours and Tokyo to Shimonoseki in about nine. Shima Yasujiro, a long-standing advocate of standard gauge, was its leading promoter.

The plan and its funding were approved in 1940 (Cabinet approval and a budget of about 556 million yen passed by the Imperial Diet), with completion scheduled in fifteen years, in 1954. Work started with the most difficult tunnel sections: the Shin-Tanna Tunnel (Atami–Kannami) in August 1941, the Nihonzaka Tunnel (Shizuoka–Yaizu) in 1941, and the Shin-Higashiyama Tunnel in Kyoto, begun from its east portal in July 1941.

In 1943, with the Pacific War turning against Japan, all work was ordered stopped. By then pilot headings of the Shin-Tanna Tunnel had been driven 647 m from the Atami side and 1,433 m from the Kannami side, and it was left partially excavated. The Nihonzaka Tunnel (2,174 m) was completed in 1944 and lent to the Tokaido Main Line from that year until 1962; the Shin-Higashiyama Tunnel (1,885 m) was completed in August 1944 and opened on 1 December 1944 as an additional track of the Tokaido Main Line.

The wartime land purchases and route surveys were inherited by the postwar Tokaido Shinkansen project, planned under Shima Hideo, son of Shima Yasujiro. Work on the Shin-Tanna Tunnel resumed in 1959 and it was finished at a length of 7,959 m; the Nihonzaka Tunnel was handed back in 1962 for Shinkansen use; and the line opened on 1 October 1964. The Shin-Higashiyama Tunnel, by contrast, stayed with the conventional line, because the Shinkansen route east of Kyoto was changed and a separate Higashiyama Tunnel was bored for it. A district of Kannami, Shizuoka Prefecture, is still called 'Shinkansen', a name said to derive from the housing built for the tunnel workers, and a trace of the Bullet Train Plan left on the map.