How to reduce the noise emitted by a train?

How to reduce the noise emitted by a train?

To reduce noise inside a train, we can use natural ventilation systems (quieter than electric fans) to cool components that generate a lot of heat; create closed motors to avoid whistling; develop the design of the front end and bottom of the train to limit exposure to wind; use electric braking, much quieter than mechanical braking; and install hoods on the pantograph, to prevent whistling noises from the roof.

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