The Shinkansen (新幹線?, new trunk line), also known as the "Bullet Train", is a network of high-speed railway lines in Japan operated by four Japan Railways Group companies. Starting with the Tōkaidō Shinkansen in 1964, the network has expanded to currently consist of 2,387.7 km (1,483.6 mi) of lines with maximum speeds of 240–300 km/h (149–186 mph), 283.5 km (176.2 mi) of Mini-shinkansen lines with a maximum speed of 130 km/h (81 mph), and 10.3 km (6.4 mi) of spur lines with Shinkansen services. The network presently links most major cities on the islands of Honshu and Kyushu, with construction of a link to the northern island of Hokkaido underway and plans to increase speeds on the Tōhoku Shinkansen up to 320 km/h (199 mph). Test runs have reached 443 km/h (275 mph) for conventional rail in 1996, and up to a world record 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.
The Tōkaidō Shinkansen is the world's busiest high-speed rail line. Carrying 151 million passengers a year (March 2008), it has transported more passengers (over 4 billion, network over 6 billion) than any other high speed line in the world. Between Tokyo and Osaka, the two largest metropolises in Japan, up to thirteen trains per hour with sixteen cars each (1,323 seats capacity) run in each direction with a minimum headway of three minutes between trains. Though largely a long-distance transport system, the Shinkansen also serves commuters who travel to work in metropolitan areas from outlying cities.