Rail Gauge in Japan

Japan's first railway, between Tokyo and Yokohama, opened in 1872 on the 1,067 mm gauge. Why this gauge was chosen is debated: the two explanations most often given, that Britain treated Japan as a colony and that a narrow gauge suited the tight curves of a mountainous country, have both been questioned. The state network was then extended on the same narrow gauge, which became the national standard. It is often called "Cape gauge" — a name that comes not from Japan but from southern Africa, where the same 3 ft 6 in gauge was used in the Cape Colony.

Not everyone was content with the narrow gauge. Around 1887 the army and others called for conversion to 1,435 mm, but Inoue Masaru, head of the Railway Bureau, rejected the demand: with not even the Tōkaidō Main Line yet open, he argued, extending the network had to come first. The question came back more than once as traffic grew, and in the early twentieth century it became a national policy debate. Gotō Shinpei, who in 1908 became the first president of the newly created Railway Agency (Tetsudōin), proposed converting the network to 1,435 mm standard gauge — the "upgrade first" position (kaishu-kenju) — and in 1909 ordered a survey comparing the construction and operating costs of 1,435 mm and 1,067 mm lines. Under his direction the agency also made a technical study of conversion. Wider track promised faster, heavier trains.

Against this stood the "build first, regauge later" position (kenshu-kaiju) of the Rikken Seiyūkai party led by Hara Takashi, which held that limited funds were better spent extending cheap narrow-gauge lines to as much of the country as possible than on regauging the trunk routes that already existed. The enormous cost of conversion made the question a matter of party politics, and the politics decided it. After Hara became prime minister he installed Tokonami Takejirō at the head of the Railway Agency, and on 24 February 1919 Tokonami told a special committee of the House of Peers that wide gauge was unnecessary. That year the Hara cabinet chose to put extending the network first, ending the plan to convert to 1,435 mm for good. The country would expand its narrow-gauge network instead.

Standard gauge nonetheless found a place in Japan alongside the narrow-gauge state railways, mostly on privately built urban and interurban lines. Many private railways in the Kansai region — and a number of subway and tram systems — were laid to 1,435 mm. A few operators that had opened on other gauges later converted: the Keisei Electric Railway, for instance, regauged its entire 75.7 km network between 9 October and 1 December 1959. As of around 2009 Japan had roughly 22,301 km (13,857 mi) of 1,067 mm line against about 4,251 km (2,641 mi) of 1,435 mm standard gauge, with two smaller gauges also surviving.

Those smaller gauges add to the patchwork. About 96 km (60 mi) of track is laid to the unusual 1,372 mm (4 ft 6 in) "Scotch gauge," used today for the Keiō Line, the Toei Shinjuku Line built to match it, Tokyo's two surviving tram lines (the Toden Arakawa Line and the Setagaya Line), and the Hakodate City Tram. A further 48 km (30 mi) of regional line keeps the very narrow 762 mm (2 ft 6 in) gauge once common on Japan's light railways. The reason gauge matters so much is through-running: a train can only run straight from one company's tracks onto another's if the rails are the same distance apart, so a difference in gauge divides networks that are otherwise connected.

When the Tōkaidō Shinkansen opened in 1964, it was laid to 1,435 mm standard gauge on an entirely separate, purpose-built alignment, free of the curves and width limits of the old narrow-gauge lines and able to run far faster than anything the 1,067 mm network could carry. The trade-off was that Shinkansen trains could not reach cities off the high-speed lines. The answer, decades later, was the "mini-Shinkansen": rather than build full new Shinkansen lines to regional cities, JR East regauged existing narrow-gauge routes from 1,067 mm to 1,435 mm so Shinkansen trains could run straight through. The Yamagata Shinkansen converted the Ōu Main Line between Fukushima and Yamagata, opening with 400 series trains on 1 July 1992, and was extended to Shinjō on 4 December 1999. The Akita Shinkansen followed on 22 March 1997, regauging the Tazawako Line from Morioka to Ōmagari and running standard-gauge and narrow-gauge tracks side by side on the Ōu Main Line from Ōmagari to Akita; it was worked by E3 series trains. Because only the rail gauge was changed and the lines kept their conventional loading gauge, mini-Shinkansen cars are built narrower than full Shinkansen stock, and their top speed on the regauged sections is 130 km/h, the same as on high-standard narrow-gauge lines.

• 1872Japan's first railway, Tokyo–Yokohama, opens built to 1,067 mm (3 ft 6 in) gauge.
• 1873The Cape Colony uses 3 ft 6 in gauge, the origin of the name "Cape gauge."
• 1887Around this year Railway Bureau chief Inoue Masaru rejects a demand from the army and others to regauge to 1,435 mm, putting extension of the network first.
• 1908Gotō Shinpei becomes the first president of the newly created Railway Agency (Tetsudōin) and proposes converting the network to 1,435 mm standard gauge.
• 1909Gotō orders a survey comparing the construction and operating costs of 1,435 mm and 1,067 mm lines.
• 1919On 24 February Tokonami Takejirō, Railway Agency president under PM Hara Takashi, tells a special committee of the House of Peers that wide gauge is unnecessary; the Hara cabinet puts extending the network first (kenshu-kaiju), ending the plan to convert to 1,435 mm.
• 1959Keisei Electric Railway regauges its entire 75.7 km network (9 October – 1 December).
• 1964The Tōkaidō Shinkansen opens as a brand-new 1,435 mm (4 ft 8½ in) standard-gauge line, separate from the narrow-gauge network.
• 1992The Yamagata Shinkansen opens on 1 July: the Ōu Main Line from Fukushima to Yamagata is regauged from 1,067 mm to 1,435 mm as a mini-Shinkansen route so Shinkansen trains can run straight through, worked by 400 series trains.
• 1997The Akita Shinkansen opens on 22 March: the Tazawako Line (Morioka–Ōmagari) is regauged from 1,067 mm to 1,435 mm as a mini-Shinkansen route, with standard-gauge and narrow-gauge tracks side by side on the Ōu Main Line from Ōmagari to Akita; worked by E3 series trains.
• 1999The Yamagata Shinkansen is extended to Shinjō (4 December).
• 2009Reported network: ~22,301 km of 1,067 mm narrow gauge, ~4,251 km of 1,435 mm standard gauge, 96 km of 1,372 mm, and 48 km of 762 mm.