is the name given to the concept of converting existing narrow gauge railway lines to to allow operation of Shinkansen services in Japan. While the track gauge is widened, the original loading gauge is retained, requiring the use of specially designed Shinkansen rolling stock with a narrower cross-section, leading to the "mini-Shinkansen" designation.
Unlike purpose-built high-speed Shinkansen lines, mini-Shinkansen routes are constrained by their legacy infrastructure to maximum operating speed of . Two mini-Shinkansen routes have been constructed: the Yamagata Shinkansen, which opened in 1992, and the Akita Shinkansen, which opened in 1997. Both connect to the high-speed TÃ Âhoku Shinkansen for direct service to and from Tokyo.
The mini-Shinkansen concept was first considered by Japanese National Railways (JNR), but was not formally proposed until November 1987, following the formation of East Japan Railway Company (JR East). The concept involves regauging existing narrow gauge lines to the used on the Shinkansen network, to allow through-running on a main high-speed Shinkansen line. While the track gauge is widened, the loading gauge remains unchanged, requiring specialized rolling stock with a narrower cross-section, compared to the standard width.
To compensate for the narrower car bodies, these trains generally have 2ÃÂ2 seating in ordinary class, compared with the 2ÃÂ3 configuration of typical Shinkansen trains, and are fitted with retractable gap fillers that flip up at main line Shinkansen stations to bridge the gap between the train and the platform.
Mini-Shinkansen sets are capable of high-speed operation on Shinkansen tracksâÂÂup to for the E6 seriesâÂÂeither on their own or coupled to full-sized Shinkansen sets. On converted narrow-gauge lines, they operate at conventional speeds of around , although track improvements can enable higher speeds where feasible.
The first mini-Shinkansen route was the Yamagata Shinkansen, converted from the a section of the à Âu Main Line between Fukushima on the Tohoku Shinkansen and Yamagata in Yamagata Prefecture. Conversion work began in 1988, and Yamagata Shinkansen services commenced on 1 July 1992, operated by a new fleet of 400 series trains operating Yamabiko services. Trains ran at up to on the Tà Âhoku Shinkansen section and on the Yamagata Shinkansen section. Following the success of the initial conversion, a further of track was re-gauged to reach Shinjà Â, opening on 4 December 1999. The introduction of E8 series trains on the line in 2024 increased the maximum operating speed on the Tà Âhoku Shinkansen section to .
Following the success of the Yamagata Shinkansen, a second mini-Shinkansen route was developed from Morioka in Iwate Prefecture, then the northern terminus of the Tà Âhoku Shinkansen, to Akita in Akita Prefecture. This involved regauging the Tazawako Line from Morioka to à Âmagari and of the à Âu Main Line from à Âmagari to Akita. The Akita Shinkansen opened on 22 March 1997 with E3 series trains operating Komachi services. The introduction of E6 series trains on the line in 2013 enabled the maximum operating speed on the Tà Âhoku Shinkansen section to be increased to in 2014.
The following rolling stock has been built for use on mini-Shinkansen lines: