Introduction to the Bullet Train

Japan’s high-speed bullet train is the world’s most technologically advanced, capable of reaching nearly 300 kilometers per hour, and has transported the equivalent of the entire earth’s population in its lifetime. The development of the bullet train involved surprising engineering connections, including inspiration from ancient chariot racing, medieval clocks, and 19th-century luxury cars, to overcome the challenges of Japan’s rugged and mountainous terrain.

Engineering Challenges and Solutions

High-speed train engineers face challenges, including a phenomenon where the train’s carriage moves from side to side, known as hunting oscillation, which can lead to derailment even on straight tracks. To address this, engineers compromise on the cone angle of the train wheels to balance curve navigation and stability. Additionally, the use of coiled springs helps to absorb up-and-down motion and dampen side-to-side rocking, allowing the train to move smoothly at high speeds with minimal sideways movement.

• The conical shape of train wheels allows them to move around curves, but this can cause instability on straight tracks, especially at high speeds.
• The combination of specially designed wheels and coiled springs enables the train to roll straight and wear a perfect line along the rails.
• Engineers have also developed a system to power the bullet train, using a pantograph to collect electricity from overhead lines, and have implemented a solution to prevent the pantograph from losing contact with the wire, using a simple lever to keep the pantograph pressing against the wire.

Power and Traction

To power the bullet train, engineers increased the voltage to 25,000 volts, but this creates a risk of catastrophic damage if the pantograph loses contact with the wire. To address this, engineers have developed a system to prevent the pantograph from losing contact with the wire. Additionally, the bullet train uses a multiple unit system, where most carriages have their own motors, providing good traction and allowing for quick acceleration.

• The concept of four-wheel drive, pioneered by the 1899 Porsche, has been applied to the bullet train, improving its grip and performance.
• Engineers have also developed a system to convert power to speed, requiring the right balance of power and grip, and considering the train’s weight, as a lighter weight is beneficial for achieving high speeds.

Cornering and Centrifugal Force

Bullet trains are so fast they need to lean further into bends, and banking alone is not enough to ensure a comfortable ride. To address this, bullet train engineers use simulators to test the train experience, including cornering at high speeds. The latest bullet train, the N700, features computer-controlled airbags that allow it to tilt independently as it corners, making it possible to maintain high speeds while keeping travelers safe and on time.

• The concept of leaning into turns, used by ancient charioteers, has been applied to the bullet train, allowing it to corner quickly without losing control.
• Engineers have also developed a system to mitigate centrifugal force, using a combination of banking and tilting to ensure a smooth ride.

Earthquake Warning System

Japan is highly prone to earthquakes, with around 900 occurring annually, and the risk of derailment is a significant concern for high-speed trains. To address this, engineers have developed a sophisticated earthquake warning system, using a network of seismometers to detect seismic activity and automatically stop trains within a 3-kilometer stopping distance. The system has been successful in stopping trains during earthquakes, and engineers have also developed a cutting-edge anti-derailment system to further improve safety.

• The earthquake warning system uses a combination of seismometers and electromagnets to detect tiny movements and pulses of P waves, aiming to improve earthquake detection and warning systems.
• Engineers have also developed a simple but effective solution to keep trains on track during earthquakes, fitting an extra rail to hold the wheels in place, and have tested this idea using a 1/5 scale model train set with an earthquake simulator.