Rail Gauge in Japan

When Japan opened its first railway between Shimbashi in Tokyo and Yokohama in 1872, the work was directed by foreign engineers, and the 1,067 mm gauge was proposed by the British civil engineer Edmund Morel, drawing on his earlier experience building railways in New Zealand. The narrower gauge was cheaper to build through Japan's hilly, often cramped terrain: tighter curves, narrower earthworks, and lighter structures all cost less than a full standard-gauge line. The decision was practical rather than ideological, but because the first line set the pattern, every line built afterward followed it, and the narrow gauge became the de facto 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 adopted as the standard for the Cape Government Railways in the Cape Colony in 1873, a year after Japan's first line opened.

Not everyone was content with the narrow gauge. As early as around 1887 the railway administrator Inoue Masaru, then head of the railway bureau, rejected calls to convert the lines, defending 3 ft 6 in as appropriate for Japan. The argument resurfaced more forcefully in the early twentieth century as a national policy debate. Gotō Shinpei, who became the first president of the Railway Agency (Tetsudōin) in 1908, championed converting the network to 1,435 mm standard gauge — the "upgrade first" position (kaishu-kenju) — and in 1909 ordered detailed studies comparing the construction and operating costs of 1,435 mm and 1,067 mm lines. Wider track promised faster, heavier, more powerful trains.

Against this stood the "build first, regauge later" camp (kenshu-kaiju) led by Hara Takashi and the Rikken Seiyūkai party, who argued 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 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 — effectively ending Japanese National Railways' plan to convert to 1,435 mm. The country would expand its narrow-gauge network instead.

Standard gauge never vanished from Japan entirely; it simply grew up 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 in stages 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 runs on the unusual 1,372 mm (4 ft 6 in) "Scotch gauge," used today for the Keiō Line, the Toei Shinjuku Line that interruns with 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: trains can only pass from one company's tracks onto another's, or share a station's platforms, if the rails are the same distance apart, so a mismatch in gauge is a hard wall between otherwise-connected networks.

That wall is exactly why the Shinkansen was built new. 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 high-speed lines to smaller 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 87.1 km of the Ōu Main Line between Fukushima and Yamagata, opening with 400 series trains on 1 July 1992 and later extending 61.5 km to Shinjō on 4 December 1999. The Akita Shinkansen followed on 22 March 1997, regauging the 75.6 km Tazawako Line from Morioka to Ōmagari plus 51.7 km of the Ōu Main Line on to Akita, worked by E3 series trains. Because only the rail gauge was widened and not the older lines' loading gauge, mini-Shinkansen cars are built narrower than full Shinkansen stock and run at around 130 km/h on the regauged sections — a pragmatic compromise that, in its own way, echoes the cost-minded choice made back in 1872.

• 1872Japan's first railway, Shimbashi–Yokohama, opens built to 1,067 mm (3 ft 6 in) gauge, proposed by British engineer Edmund Morel.
• 1873The Cape Government Railways in the Cape Colony adopt 3 ft 6 in gauge, the origin of the name "Cape gauge."
• 1887Railway bureau chief Inoue Masaru rejects demands to regauge, defending 3 ft 6 in as suited to Japan.
• 1908Gotō Shinpei becomes the first president of the Railway Agency (Tetsudōin) and pushes for 1,435 mm standard gauge.
• 1909Gotō orders detailed cost studies comparing 1,435 mm and 1,067 mm construction and operation.
• 1919On 24 February, under PM Hara Takashi, Tokonami Takejirō tells the House of Peers wide gauge is unnecessary, ending JNR's 1,435 mm conversion plan.
• 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 8+1/2 in) standard-gauge line, separate from the narrow-gauge network.
• 1992Yamagata Shinkansen opens 1 July: 87.1 km of the Ōu Main Line (Fukushima–Yamagata) regauged 1,067→1,435 mm, worked by 400 series trains.
• 1997Akita Shinkansen opens 22 March: the 75.6 km Tazawako Line (Morioka–Ōmagari) and 51.7 km of the Ōu Main Line (to Akita) regauged, worked by E3 series.
• 1999The Yamagata Shinkansen is extended 61.5 km 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.