The Shinkansen, known colloquially as the “bullet train” in English, is a masterclass in innovation. 

A speed of 177 mph.

Approximately 7 billion passengers transported since its inauguration in 1964.

Not a single passenger fatality due to derailments or collisions.

An average delay of just 1.6 minutes.

The train is known for its speed, safety, and reliability, but one of its most remarkable features is its noise—or lack thereof.

To prevent noise pollution, the Shinkansen’s noise is limited to 70 decibels in residential areas. That’s roughly equivalent to the noise of a washing machine or the noise inside a car driving at 60 mph.

This is the story of how the engineers managed to make a 177 mph train that weighs hundreds of tons sound no louder than a washing machine, all with the help of a little, unassuming bird.

Superfast Train + Narrow Tunnel = Big Boom

In order to achieve its high speeds safely, the Shinkansen operates on dedicated tracks that go through, instead of around, geographic obstacles, making use of many tunnels, some of them quite long. This is the crux of the noise problem.

When a train travels on an open track, the air it displaces can be pushed in every direction except the ground. In a tunnel, though, the walls confine the air, forcing it down a single path: the length of the tunnel. Behind the train, as air is pushed away, suction is created, pulling even more air into the tunnel at the front of the train. The result is a compressed wave of high-pressure air at the front of the train. 

This is called the piston effect, because the train (or other moving object) functions like a piston. Just as a piston transfers force, when a high-speed train exits a tunnel, it pushes out that build-up of high-pressure air, releasing a loud boom. 

As the engineers worked to make the Shinkansen faster, the so-called tunnel booms grew too loud. They could be heard up to 400 meters away and exceeded the 70 dB limit. The engineers were stuck between a rock and a hard place. How could they make the train faster while also lowering the noise?

Train + Kingfisher = Faster, Quieter Ride 

Enter Eiji Nakatsu. Nakatsu was one of the engineers working on the Shinkansen. He was also a bird-watcher.

One bird in particular had sparked his interest: the kingfisher. The kingfisher is a striking bird, with brilliant blue-green feathers and a rust-orange belly. They are, as their name suggests, fishers. They catch fish by diving headfirst into the water at speeds of up to 25 miles per hour. At that speed, with surface tension, the impact should ostensibly give them a concussion. Yet instead, they glide effortlessly from air into water with hardly a splash. Researchers hypothesize that kingfishers may have actually evolved a brain structure that helps prevent concussions, but there’s another obvious factor at play: the kingfisher’s beak. 

The kingfisher’s beak is long and narrow, gradually widening as it approaches the bird’s head. If the shape of the beak could smooth the transition from air to water for the bird, Nakatsu theorized it could work for the train as well. Like a true innovator, he tested the hypothesis. In a test fitting of the Shinkansen’s English moniker, the team got bullets shaped like the different train nose models. They then shot them down a pipe to measure the pressure waves and dropped them into water to measure the splash. The bullet that did best in the tests was the one that most closely mimicked the kingfisher’s beak.

With evidence to back up the hypothesis, the team went ahead with design and manufacturing. The redesigned train, with its kingfisher nose, reduced energy consumption by 15%, increased speeds by 10%, and reduced noise levels. The impossible problem had been solved, thanks to the kingfisher.

The Cheat Code: Biomimicry

The kingfisher was not the only bird that influenced the design of the Shinkansen. The redesign also incorporated elements that were based on the wings of an owl and the body of an Adélie penguin.

This is the cheat code: biomimicry. The Earth is about 4.5 billion years old, and life has existed here for at least 3.5 billion years. That is billions of years of trial and error and the fine-tuning of evolution.

Often, the real secret to innovation is not inventing something entirely new but finding the right solution that already exists in the world that you can apply to your particular problem. For instance, at PCDworks, when we were working on a problem with pumps, we looked to the giraffe, because what is a giraffe’s heart but a pump that manages to move blood all the way up a 7-foot neck?

The next time you face a seemingly unsolvable problem, try looking to nature for the solution.