The unreal science of Japan's 400kph bullet trains explained

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2023-05-26 17:00:05

In the 1990s, engineer Eiji Nakatsu drew inspiration for a redesign of Japan’s high-speed bullet train from the slender profile of a kingfisher’s beak. Its latest iteration looks like a quite different part of the anatomy.

The ALFA-X (which stands for Advanced Labs for Frontline Activity in rail eXperimentation) will become the world’s fastest bullet train when it enters service in 2030. It’s capable of hitting speeds of up to 400kph — 80kph more than the current generation of Shinkansen trains.

The train’s ten carriages have a number of features to help cope with the increased velocity, including air brakes on the roof, and magnetic plates positioned near the rails that will help them decelerate.

But the ALFA-X’s most eye-catching feature is its elongated nose, an exaggerated version of Nakatsu’s 1997 design. Engineers are testing both 16- and 22-metre long versions of the nose during three years of night-time trials between the cities of Aomori and Sendai, which commenced last week.

The nose is designed to combat side effects of what engineers call the ‘piston effect,’ caused by trains pushing air through tunnels as they enter. “It’s like a piston going into its cylinder,” explains David Soper, a lecturer in vehicle aerodynamics at the University of Birmingham’s Centre for Railway Research and Education. “As the train enters into the tunnel it sets up pressure waves – it comes down to train shape, length, and speed.”