Trains do make noise when they pass over rails, but the amount of noise can vary depending on several factors. Here are a few reasons why you might perceive trains as relatively quiet when they pass over rails:
Distance and sound attenuation: The sound produced by a passing train can be attenuated or reduced as it travels through the air. The farther you are from the train, the more the sound waves spread out, and the quieter the train may appear. If you are located far away from the tracks, the sound may be significantly reduced by the time it reaches your ears.
Track design and maintenance: Modern railway tracks are designed to minimize noise as much as possible. They often incorporate techniques such as using continuously welded rails, rubber or elastic pads between the rails and sleepers, and ballast that helps absorb vibrations. These measures can help reduce the transmission of noise generated by the train's wheels and passing vibrations through the tracks.
Train technology and design: Trains today are built with noise reduction in mind. They feature improved wheel and rail profiles, damping systems, and sound insulation materials to mitigate noise production. The use of electric trains, which have quieter propulsion systems compared to diesel trains, can also contribute to a reduction in overall noise levels.
Speed and train type: The speed at which a train is traveling can influence the noise it produces. Trains traveling at higher speeds tend to generate more aerodynamic noise due to air resistance, which can overshadow the sound produced by the wheels on the tracks. Additionally, different types of trains, such as high-speed trains or trains with specially designed noise-reducing features, may produce less audible noise compared to conventional trains.
While trains have certainly become quieter over the years due to advancements in technology and engineering, they still generate noticeable noise when passing over rails, especially if you are in close proximity to the tracks. However, factors such as distance, track design, train technology, and speed can contribute to the perception of trains being relatively quiet when they pass by.