# Reducing Railway Track Vibrations by Applying Particle-Damping Systems
## 1 Introduction  
Noise and vibration have a severe impact on people's health and well-being, and this influence has greatly increased in recent years, mainly due to the significant increase in traffic over the years from several different modal transportation systems, like trains, cars, and planes. [PERSON] et al. [1] performed extensive research regarding the impact of road and rail noise on people's lives and found that traffic has amplified severe health issues, like sleep disturbances and noise annoyance. Although trains are well known for being very efficient and eco-friendly (when compared to other modal transportation systems), they also have a negative impact on people's health, mainly due to excessive noise and vibration levels. Regarding this topic, several interviews were conducted by [PERSON] et al. [2] about the perception of vibrationsgenerated by rails in nearby communities. They have observed that there is a general feeling about the increase in traffic, speed, and noise. Moreover, several individuals have reported great concern regarding vibrations, with some experiencing glasses shaking in display cabinets, wall pictures moving out of place, and cracks appearing and growing in the walls. Regarding symptoms, people reported increases in stress levels, irritation, tiredness in the morning and difficulty sleeping. [PERSON] et al. [3] developed an interesting work investigating the effect of freight train traffic on people's health, especially regarding sleep. They have found that vibration levels have several different impacts, such as poor sleep, awakenings overnight, difficulty falling asleep, and tiredness. Another work focusing on train impacts on people's quality of sleep was developed by [PERSON] et al. [4]. They have monitored the heart rates of individuals during sleep and have found that the vibration generated by the train had a significant impact on increasing heart rates. Moreover, they have observed that these variations remained even after dozens of seconds. Such variations reduce the rest effectiveness during sleep, increasing stress levels and other negative impacts on human health. Some authors found strong relations between a lack of proper maintenance and the noise emitted by the trains [5]. They have measured the roughness for several train lines and found that several of them were outside the standard limits. Another work concerning wear and its impact on the noise was conducted by [PERSON] et al. [6]. They have developed a real-time monitoring system for rail conditions. Once more, a stronger correlation between noise levels and track wear was observed, where very high noise levels were measured in severely worn track sections. Within the noise generated by train topics, [PERSON] et al. [7] quantified the contribution of each train part to the total noise generated by a train. They have found that the bogie and other lower-region parts were one of the main contributors. Regarding vibrations generated by train and their impact, a wide-ranging review study was conducted by [PERSON] et al. [8]. Some authors were able to successfully correlate vibration amplitude with annoyance levels in people in the vicinity of railroads [9]. They have observed that complaining reports regarding noise and vibration in areas close to railroads increased drastically over the last years. Moreover, it was found that when vibrations were measured, in more than 40% of the cases, vibration levels exceeded the national or international allowable limits. They have observed that in approximately 1/3 of the studied cases, the threshold for ground-borne noise from freight trains was exceeded, although more data are required to draw more conclusive statements. Another work focusing on the impacts of vibration generated by trains was developed by [PERSON] et al. [10]. Since isolating structures that are already built from these vibrations is often too expensive, understanding and controlling these vibration levels is essential.