The Shinkansen 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 in and outside Japan to refer to the trains running on the lines as well as the system as a whole. The name "Superexpress", initially used for Hikari trains, was officially retired in 1972 but is still used in English-language announcements and signage. The Tōkaidō Shinkansen opened on October 1, 1964, in time for the Tokyo Olympics. Conventional Limited express ran from Tokyo to Osaka in 6h40, but Shinkansen ran in only 4h00, and in 1965 shortened to 3h10. It was an immediate success, reaching the 100 million passenger mark in less than three years on July 13, 1967 and one billion passengers in 1976. Sixteen-car trains were introduced for Expo '70 in Osaka.