9:01
To coincide with the 1964 Tokyo Olympics, Japan launched the world's first high-speed train, the Shinkansen, capable of running at 210 km/h. This groundbreaking bullet train inspired countries around the world to invest in high-speed rail. Today, these trains regularly travel at over 300 km/h, on par with the takeoff speed of a commercial airplane. But, could these trains go even faster, whisking passengers to their destinations quicker than the smoothest flight? To answer this, it helps to understand how these trains reach their already impressive speeds. There are three main factors that separate bullet trains from traditional low-speed
trains: engines, aerodynamics, and infrastructure. Most traditional trains are powered by combustion engines, which combust fuel, typically diesel, to turn an electric generator. This electricity is then used to power motors that turn the train's wheels. High-speed trains, on the other hand, use electric engines to power their motors. This process is more energy efficient than combustion, and allows train operators to reach top speeds more quickly. Next up is aerodynamics. While low- and high-speed trains use the same steel wheels to minimize friction with the track, bullet trains are also designed with aerodynamic bodies that slice through air with minimal resistance.
Engineers could use these slicker designs on traditional train cars. But while upgrading to electric engines would make low-speed trains more efficient, they wouldn't get much benefit from these aerodynamic designs because of the third factor, infrastructure. Traditional train tracks were built to meet people where they lived, ensuring stations were accessible to any potential passengers. But to prevent derailments in these highly populated areas, trains need to frequently decelerate to safely hit turns and crossroads. High-speed rails, on the other hand, were built to prioritize speed. They run on long, straight lines that avoid road crossings, sharp curves, and high-traffic areas.
These three differences allow high-speed trains to reach top speeds over double their traditional counterparts. And since their infrastructure allows them to travel longer distances between stops, they spend more time cruising near top speed, often traveling up to three times the average speed of traditional trains. But new technology is emerging to make even faster trains. To eliminate friction between rails and wheels, engineers have developed new magnetic levitation, or maglev, trains. There are two major approaches here. In electromagnetic suspension, magnetized arms wrap under the track and pull the train up. Meanwhile, in electrodynamic suspension, coils embedded in the track create a pattern of alternating magnetic fields
that interact with magnets on the train to float the vehicle a few centimeters in the air. To change speed, train operators alternate the direction of the train's magnetic field, attracting the front of the train to the next coil to speed up, or reversing the field's phase to brake. Given enough runway, these trains can reach speeds from 430 to a theoretical 600 km/h, allowing them to make the over 4,400 km trip from New York City to Los Angeles in as little as 7 hours. So, why haven't we built Maglev trains or even high-speed trains everywhere? First, these trains require lots of energy, most of which is needed to overcome air resistance. In fact, at 300 km/h, this task accounts for over 80% of train's energy consumption.
Engineers are researching ways to reduce air resistance, such as putting Maglevs in near vacuum environments. But, building a vacuum-sealed tunnel across an entire country would be an infrastructure project of science-fictional proportions. Besides, it's hard enough to build regular high-speed rails. To go fast, trains need long, straight tracks with wide curves, which are very difficult to build in mountains, cities, or densely populated areas. Building such routes is costly, politically sensitive, and often physically impossible. Despite these hurdles, Japan and China are expanding their existing high-speed and Maglev rails, and several projects currently in development might finally bring
high-speed rail to the US. But, we'll need to carefully consider our trains' top speeds alongside cost, energy use, and safety to keep the future of train travel on the right track. And that future could include you. Brilliant can help you master the fundamentals of math and programming with a visual interactive tutor that asks guiding questions, draws diagrams, and adapts in real time to your learning needs. Visit brilliant.org/ted-ed to get started with Brilliant's tutor for free and 20% off an annual premium subscription.
