• Jiji, Staff Report

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Calculations by Japan’s Fugaku supercomputer have found that opening and closing doors of a local commuter train when it stops at stations brings about the same level of ventilation as from keeping windows of a train open while it is running, government-affiliated research institute Riken said.

In the research, which was conducted as Japan continues to struggle with the novel coronavirus, a Riken team led by Kobe University professor Makoto Tsubokura calculated the amounts of ventilation in the front cars of commuter trains by simulating the flow of air under various conditions, such as how much windows are open and how frequently doors are opened at stations.

The team assumed that the trains travel at a speed of 80 kilometers per hour and have air conditioning running for ventilation and that the front cars are overloaded with passengers. While showing that the more open the windows are, the greater the ventilation effect is, the calculations found that the air in the cars is exchanged vigorously through the doors when they are opened and closed at stations.

If its doors are opened for 45 seconds while at stations, a local train that stops at a station about every two minutes can secure the same amount of ventilation as that for a train with its windows open by 5 centimeters while traveling, according to Riken.

“For trains that stop very frequently, such as those on the Yamanote Line, you can get as much ventilation effect through opening and closing the doors as through keeping the windows open,” Tsubokura said, citing the busy loop line in Tokyo. As it gets colder, how often trains stop at stations can be used as a benchmark to decide whether and to what degree train windows are opened, Tsubokura said.

According to its website, East Japan Railway Co., which operates the Yamanote Line, runs all services with carriage windows opened between 5 and 10 centimeters. Along with air conditioning and the opening of doors, this allows the air inside carriages to be changed every 2 to 3 minutes.

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