The Light-weight Electric Car with Arc-shaped Body;
Tokyu 5000 Series

In 1954, Tokyu Car Corporation (now Japan Transport Engineering Company) developed an all-steel high-speed commuter train (Tokyu 5000 series) to increase the speed of the Tokyu Toyoko Line. During this development, the company's former aeronautical engineers disregarded the unwritten rule that the sides of steel car bodies should be formed in a vertical plane by adopting a stretched shell structure with a curved contour and a circular cross-section. It was named an “ultralight train” because the electric car was more than 10 tons lighter than its predecessor. The light weight of the car body enabled the train to travel at 105 km/h, connecting Shibuya and Sakuragicho in 34 min and significantly reducing travel time. It was popularly known as a “wingless airplane” because it uses a round tube for a railroad car body, which had previously been a square box, and as a “blue frog” because of its color and shape. This basic technology was later adopted not only for high-speed trains such as the Odakyu 3000 and Shinkansen Series 0 but also for conventional line trains and is still widely used currently as the de-facto standard technology.　This car was manufactured in 1956 out of 105 cars manufactured between 1954 and 1959. After being used by Tokyu Corporation, it was reused by Nagano Electric Railway, and after retirement, it was preserved at the Yokohama Works of Japan Transport Engineering Company.