El Shinkansen (新幹線) es la red ferroviaria de alta velocidad de Japón, operada por la compañía Japan Railways. Desde que en 1964 se abrió la línea Tōkaidō Shinkansen, la red se ha ido expandiendo para conectar la mayor parte de las ciudades de las islas de Honshū y Kyūshū, con velocidades de hasta 300 km/h. Las velocidades máximas que se han alcanzado en viajes experimentales han sido de 443 km/h. La palabra Shinkansen significa literalmente "Nueva Línea Troncal" y se refiere estrictamente al trazado de las vías, mientras que los trenes propiamente dichos se denominan oficialmente "Super Expresos" (超特急, chō-tokkyū), aunque esta distinción es rara incluso en el propio Japón. Al contrario de la red original, el Shinkansen utiliza el ancho de vía normal (1.435 mm), y se vale de túneles y viaductos para atravesar "obstáculos", en vez de rodearlos. The Shinkansen (新幹線) is a network of high-speed railway lines in Japan operated by four Japan Railways Group companies. Since the initial Tōkaidō Shinkansen opened in 1964 running at 210 km/h (130 mph), the network (2,459 km or 1,528 miles) has expanded to link most major cities on the islands of Honshū and Kyūshū with running speeds of up to 300 km/h (188 mph), in an earthquake- and typhoon-prone environment. Test run speeds have been 443 km/h (275 mph) for conventional rail in 1996, and up to a world record of 581 km/h (361 mph) for maglev trainsets in 2003. Shinkansen literally means "New Trunk Line", referring to the tracks, but the name is widely used inside and outside Japan to refer to the trains as well as the system as a whole. The name "Superexpress" (超特急 chō-tokkyū), initially used for Hikari trains, was retired in 1972 but is still used in English-language announcements and signage. In contrast to older lines, Shinkansen are standard gauge, and use tunnels and viaducts to go through and over obstacles, rather than around them. It is separated from conventional rail and constructed in completely renewed railway system, using ATC (Automatic train control system without signal), minimum 4,000 meters (2,500 meters in the oldest Tōkaidō Shinkansen) radius curve and elevated tracks without roadway crossings. Tōkaidō Shinkansen is the world's busiest high-speed rail line and carries 375,000 passengers a day, and has transported more passengers (4.5 billion) than all other high speed lines in the world combined. Though largely a long-distance transport system, the Shinkansen also serves commuters who travel to work in metropolitan areas from cities beyond the metropolitan areas.