The ground-breaking ceremony of India's first high-speed rail corridor was held on 14 September 2017. A step was taken to realize the dream of the world famous 'bullet train' for the first time in India. The bullet train will run at a speed of 320 km/h on the distance of 508 km from Mumbai to Ahmedabad in the next few years. Although the implementation of this project has been delayed due to party politics, the bullet train will start running on this route in the next 3 years. This bullet train will be based on Japan's world famous 'Shinkansen' technology. Shinkansen means 'New Main Line'. This technology was started in Japan in 1964. Over the past 59 years, Shinkansen technology has advanced through many changes. Today, based on this technology, trains can safely reach speeds of up to 320 km/h. The trains of this technology are called 'bullet trains' because of their pointed shape like a bullet from the front. But this size is the reason behind the tremendous speed of this trench. Bullet trains are running today in many other countries copying this shape but this shape is taken from the beak of one bird. The story behind it is very interesting.
Eiji Nakatsu was the general manager of the technical development department of Japan's so-called "bullet train", a key figure behind the bullet train's astonishing speed and safety record. He was given responsibility to increase speed of the bullet train. But the biggest problem in increasing the speed of bullet trains was reducing their noise. Bullet trains in Japan ran through densely populated areas and many tunnels. They were making a loud noise due to their great speed. This noise was caused by two things one is the connection of overhead wires (pantograph). Due to the velocity, the air flowing over the struts and linkages of the system was creating the so-called Karman vortices effect. This effect produced most of the sound.
The second biggest problem was that there were many tunnels on the route of this train. When a train passes through a tunnel at high speed, it creates atmospheric pressure waves that travel out the other end of the tunnel at the speed of sound. Air was forced out from the other end of the tunnel as the train sped through it. This air was ejected in low-frequency waves (below 20Hz) that produced a massive sonic boom and a deafening sound. The dynamic was so powerful that it could be heard by residents 400 meters away. Many Japanese people living there had complained about this to the government. Both of these issues needed to be resolved before Eiji Nakatsu could give extra speed to bullet train.
Eiji Nakatsu was a good bird watcher. He strongly believed that we can learn a lot from nature. He started looking at birds to find answers to his questions. He was impressed by the flying style of owls. When an owl flies through the air, its wings make no sound at all. This is because the comb-like fibers on the tip of an owl's main wing reflect the air impinging on the wing foil into fine turbulence as it swoops through the air towards a target. This makes no sound at all when the owl flies through the air. Eiji Nakatsu found the answer to his first problem in owl feathers. After that, wing graph was installed in bullet train instead of pantograph. The intensity of the sound produced by it was measured below 20 Hz.
But their problems were not over yet. The sonic boom problem was more complicated because it was linked to the size of the tunnel and the speed of the train. The air pressure depended on the ratio of the tunnel size to the cross section of the speeding train. A one unit increase in the speed of the train causes a 3-fold increase in the sound intensity. Rather than changing the shape of the tunnel, it was necessary to change the cross section of the train, but the exact shape that would create the air pressure was not deciphered. So for his second problem, Eiji Nakatsu once again started studying birds. He noticed that when the Kingfisher (Khandya) bird catches fish by striking the water quickly, the water does not splash at all due to its jump. While studying this kingfisher bird, He noticed that its beak is triangular in shape tapering and rounded at the sides of the triangle. Perhaps it is because of this beak shape that the kingfisher gets its food from the water by literally slicing through the water. As the water does not splash while doing so, its prey does not anticipate its jump.
EG Nakatsu immediately called his engineer and asked him to make a bullet in this way. After researching the pressure generated by different sizes of shotgun pellets fired through a tunnel, it was clear that the beak size of the kingfisher produced the lowest pressure. The sound produced by it is very low. Eiji Nakatsu immediately ordered the creation of a bullet train of similar shape. When the new Shinkansen 500 series trains hit the tracks, the sonic boom disappear, and after their speed exceeded 300 km/h, the noise intensity remained below 70 decibels. This unique shape reduced air resistance by nearly 30%. The reduction in air resistance made a huge difference to the energy savings and speed of the bullet train. On March 22, 1997, the Shinkansen 500 series reached a speed of 300 km/h, setting a world record at the time. This bullet train also set new standards in terms of safety. At that time, this bullet train was the fastest train in the world.
Eiji Nakatsu showed that deep observation and analysis of the natural world can provide many answers. Nature has unfolded great things before us. When you become one with nature, you will find answers to your questions. Today, after almost 25 years, the same Shinkansen technology is entering India in collaboration with Japan. A bird's beak is responsible for making a bullet train faster what it achieved today. That is why when the Shinkansen bullet train based on this technology runs in Mumbai Ahmedabad in India, the technology of Kingfisher will have completed a full circle.
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