Japanese bullet trains are known for their extreme punctuality. However, when the snow appears, neither the most cutting-edge railway system of the world is saved. And to combat it, the country’s railway institutions developed a solution as simple as it was ingenious: sprinklers installed along the tracks that spray water during snowfall. This is done to prevent snow from accumulating and wreaking havoc on the trains. We explain in detail how these systems work.
Why is it important. Snow not only causes the system to stop being as punctual as usual, but it can also cause serious damage to high-speed trains. And at speeds above 200 km/h, the snow on the ground rises due to the air current generated by the train, which can cause it to compact under the cars forming ice balls that, upon impact with the ground, throw gravel into the air. This can end up breaking windows and damaging train components if left untreated.
Japan has spent decades perfecting systems to eliminate this problem without sacrificing speed or punctuality.
The origin of the problem. When the Shinkansen began regular operations in 1964, according to explains JR Tokai (the operating company of the Tokaido Shinkansen), construction was carried out in a hurry and “there was not enough time to consider” alternative routes that would avoid areas of heavy snowfall.
In January 1965, just three months after launch, snowfall in the Sekigahara region caused serious incidentsincluding broken windows and shattered water tanks. The investigation revealed that the real culprit was speed, since the wind generated raised the snow, which ended up turning into ice projectiles under the carriages.
The solution: sprinklers. To prevent the snow from rising and forming those dangerous ice balls, it was installed a sprinkler system along the tracks that sprays water during snowfall. There are currently sprinklers deployed in a stretch of more than 70 kilometers, covering the lines most affected by the snow. In 2009, the nozzles were improved so that the water reached areas that were not reached before, melting the snow more effectively.
The system does not completely remove snow, but changes its consistency to prevent it from compacting and flying, thus reducing the risk of damage.
It is not the only solution. The water system is complemented by other resources. During non-service hours, snow plows work at dawn to remove accumulated snow. Since 2003, rotary snow plows have been used that use rotating brushes capable of cleaning up to five centimeters below the surface of the rails. In addition, since 2013, devices with optical sensors have been used to monitor weather conditions, and there are cameras installed under the carriages to detect snow accumulations.
When a snow-covered train arrives at stations like Nagoya or Osaka, there are also specialized teams waiting under the platforms with high-pressure washers to quickly remove stuck-on snow.
The results speak. All of this operation has radically transformed the Shinkansen’s defenses when the snow arrives. According to JR Tokaiin 1976 there were 635 train cancellations due to snow, a figure that has been reduced to zero since 1994. The average delay due to snowfall has also improved dramatically, dropping to just a few minutes.
Beyond the trains. In the northern regions of Japan, where snowfall can exceed three meters, many roads have sprinklers integrated into the asphalt. The system, known as ‘shosetsu’ (disappearing snow) or ‘yuusetsu’ (melting snow), was developed in 1961 in the city of Nagaoka by Yosaburo Imai, founder of a century-old confectionery.
Imai was inspired by observing that snow did not accumulate where thermal water gushed from underground. Since then, underground pipes transport geothermal water (at about 13-14°C) to pavement sprinklers that melt snow during winter storms, avoiding the use of salt or snow blowers.
Cover image | KUA YUE
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