Bullet Trains

March 25, 2023

Bullet Trains

Sometimes train travel is all about the journey. It’s a great opportunity to gaze out of a window and take in the scenery on the way. Not Japan’s Shinkansen though. With bullet trains, it is all about getting to your destination AS QUICKLY AS POSSIBLE! It was the world’s first high-speed railway system, and it remains a very busy modern marvel. Let’s get you on track and up to speed. (Ha! I see what you did there, very good. Ed)

Speeding Up

The first bullet train route was the Tōkaidō Shinkansen, from Tokyo to Osaka, which opened for the 1964 Tokyo Summer Olympics. It shuttled people between the cities in 4 hours, which was a significant improvement on the old time of 6 hours and 40 minutes. But they were just warming up! Within a year, the trip time was down to 3 hours and 10 minutes. Now the 552 km (343 mile) journey takes a zippy 2 hours and 22 minutes, and counting.

Facts and Figures

Top speed: 320 km/h (GOOD GRIEF that’s fast.)

Total length of high speed system (240 km/h or more): 2,764.6 km

Total number of passengers carried: Over 10 billion

Favourite dance floor filler:
Don’t Stop Me Now, Queen. Obvs

Cool factor: Off the charts!

How to go fast

From top to toe, everything needs to be considered if a train is going to go really fast. Before we worry about the train itself, we have to think about the tracks. The faster a train goes, the worse it is at turning sharp corners. Fast trains need straight tracks, both for speed and safety.

We measure the sharpness of a corner by its curve radius – the size of the circle that the curve would make if it kept going round and round without straightening up.

The minimum (and most extreme) curve radius on the London Underground is 61 m, which means that the sharpest corner fits on a circle with a radius of 61 m. For those curious (you’re AQUILAnauts, so that’s all of you! Ed), it’s the Caxton Curve between White City and Shepherd’s Bush. The Shinkansen, on the other hand, has a minimum curve radius of 2,500 m. Bullet trains only have to go around the far gentler curves of MUCH larger circles!

But there’s a problem. Japan has got A LOT of mountains. And if you want to take a fairly straight path through the mountains, you’re going to need tunnels. And tunnels cause their own problems…cover your ears!!

Boom!

When really fast trains exit tunnels, they create a loud BOOM. The tunnel boom is a shock wave, caused by compressed air. If it gets too loud it can even damage nearby buildings, or the train itself. To stop fast trains from causing damage, Japan’s government introduced a noise pollution limit.

What they got in response was some brilliant, bird-inspired aerodynamic design.

Eiji Nakatsu, one of the engineers designing new trains, realised that moving from open air into a tunnel was a lot like moving from air into water – something that kingfishers do with barely a splash. After running computer tests on various shapes, his team then designed the front of the train to be as much like a kingfisher’s beak as possible. It worked, and the smoother flow of air around the train made the tunnel-boom much quieter!

They also quietened the regular running noise of bullet trains by improving the pantograph. The pantograph is the bit of a train that sticks out of the top to meet the overhead electrical wires and, for such a small part of the train, it sure was noisy! Inspired by the silent flight of owls, the team mimicked the serrated edges of owl feathers by serrating the edges of the pantographs. This tweak allowed the air to break up more easily, and the noise dropped right down.

As a bonus, the more aerodynamic a train is, the faster it can go, so they ended up with trains that were both quieter AND faster.

Magical Magnets

A new train line from Tokyo to Osaka, called the Chūō Shinkansen, is currently under construction. This maglev (magnetic levitation) train will run mostly underground, levitating above its rails as it goes. It runs mostly underground because, you guessed it, its minimum curve radius is HUGE at 8,000 m. But if speed is the goal, it’s worth it! Its top speed will be 505 km/h and it’ll make the trip in just 1 hour and 7 minutes! It won’t be complete until 2037 though, so right now it’s more like 14 years and 1 hour and 7 minutes.

Current Record Holder

The fastest passenger train in the world at the moment is the Shanghai maglev, in China, which runs from the international airport to the city and travels at a top speed of 431 km/h. Japan still holds the record for the fastest speed set by a passenger train under test conditions though: the L0 series maglev, intended for use on the Chūō Shinkansen, reached 603 km/h on a test track in 2015.