<P> As the Loading gauge (size of the train that can travel on a line) was not altered when the rail gauge was widened, only Shinkansen trains specially built for these routes can travel on the lines . At present they are the E3 and E6 series trains . </P> <P> Whilst no further Mini-shinkansen routes have been proposed to date, it remains an option for providing Shinkansen services to cities on the narrow gauge network . </P> <P> This is the name for the concept of using a single train that is specially designed to travel on both 1,067 mm (3 ft 6 in) narrow gauge railway lines and the 1,435 mm (4 ft 8 ⁄ in) standard gauge used by Shinkansen train services in Japan . The trucks / bogies of the Gauge Change Train (GCT) allow the wheels to be unlocked from the axles, narrowed or widened as necessary, and then relocked . This allows a GCT to traverse both standard gauge and narrow gauge tracks without the expense of regauging lines . </P> <P> Three test trains have been constructed, with the second set having completed reliability trials on the Yosan Line east of Matsuyama (in Shikoku) in September 2013 . The third set was undertaking gauge changing trials at Shin - Yatsushiro Station (on Kyushu), commencing in 2014 for a proposed three - year period, however testing was suspended in December 2014 after accumulating approximating 33,000 km, following the discovery of defective thrust bearing oil seals on the bogies . The train was being trialled between Kumamoto, travelling on the narrow gauge line to Shin - Yatsushiro, where a gauge changer has been installed, so the GCT could then be trialled on the Shinkansen line to Kagoshima . It was anticipated the train would travel approximately 600,000 km over the three - year trial . </P>

When was the bullet train in japan built