It’s a beautiful example of biomimicry, nature informing technology. The shinkansen bullet trains of Japan are airplanes on rails, traveling at over 300 km per hour in comfort and style.
Traveling at this speed, tunnels present a problem. When the train enters the tunnel it compresses a cushion of air ahead of it. The compressed air waves become a small shock wave when they exit the tunnel, moving through the air faster than the speed of sound. The tunnel boom sounds like a clap of thunder, and residents complained.
Engineers looked for examples in nature to solve the problem, and they fixed on the kingfisher. When the bird dives into the water for fish it makes hardly any splash. They generated computer models and found that modifying the nose of the train to mimic the kingfisher bill would reduce tunnel boom. The new generations of bullet trains now sport the kingfisher look and are quieter, faster and use 15% less electricity.
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