When the first Japanese Shinkansen Bullet Train was built in 1964, it could zip along at 120 mph. But going that fast had an annoying side effect. Whenever the train exited a tunnel, there was a loud boom, and the passengers would complain of a vague feeling that the train was squeezing together.
That's when engineer and bird enthusiast Eiji Nakatsu stepped in. He discovered that the train was pushing air in front of it, forming a wall of wind. When this wall crashed against the air outside the tunnel, the collision created a loud sound and placed an immense amount of pressure on the train. In analyzing the problem, Nakatsu reasoned that the train needed to slice through the tunnel like an Olympic diver slicing through the water. For inspiration, he turned to a diver bird, the kingfisher. Living on branches high above lakes and rivers, kingfishers plunge into the water below to catch fish. Their bills, which are shaped like knives, cut through the air and barely make a ripple when they penetrate the water.
Nakatsu experimented with different shapes for the front of the train, but he discovered that the best, by far, was nearly identical to the kingfisher's bill. Nowadays, Japan's high-speed trains have long, beak-like noses that help them exit quietly out of tunnels. In fact, the refitted trains are 10 percent faster and 15 percent more fuel-efficient than their predecessors.