# Possibilities of Evaluating the Effectiveness of Noise Barriers in Slovakia
## 1 Introduction  
One of the acute problems from the point of view of environmental protection is the increase of noise levels produced by transport. Noise is increasing, especially in the vicinity of traffic routes with road and rail transport. Traffic noise increases mainly with the number of vehicles and with increasing load capacity of trucks. Traffic noise is a random variable. Therefore, an equivalent noise level is used for its evaluation. Noise clearly and unequivocally produces negative effects on human health. Even today, people underestimate its harmful effects on health [1]. In 2010, according to the European Environmental Agency (EEA), noise from railway transport during the day affected approximately 12 million inhabitants of the European Union where the sound pressure level was higher than 55 dB, and approximately 9 million inhabitants were affected by the noise at night [2]. Around 56 million people (54%) in the European Union live in places with more than 250,000 people, and they are subjected to road traffic noise of more than the average LDEN (day-evening-night) of 55 dB per year,which is regarded as health threatening [3; 4]. In Slovakia, the situation is similar, as the length of roads is about 5 times longer than railway lines (18,000 and 3600 km, respectively). Currently, modernization of the railway infrastructure is underway on the railway lines of the main corridor Kosice-Zilina-Bratislava in Slovakia, associated with the transition to a qualitatively new higher standard, which includes the use of new types of trainsets, some with tilting bodies, that will be able to operate on a modernized line at a speed of up to 160 km/h [5]. As for road transport in Slovakia, highways have been under construction since 1972. The D1 highway is the oldest and longest of them, which connects Bratislava, Trnava, Trncin, Zilina, Martin, Poprad, Presov, Kosice, and the Slovak-Ukrainian border. It is part of the European roads E50, E58, E75, E442, and E571 [6]. In this context, the environmental impacts of this modernization are also important areas. The greatest impacts of transport on the environment include noise and vibration and their impact on inhabitants living near traffic lines [7; 8]. Unlike road traffic, where permissible limits for noise sources have existed in the EU since the 1970s, noise standards for railways did not come into force until the beginning of the 21 st century [9]. In 2007, Decree 549/2007 of the Ministry of Health of the Slovak Republic [10] was issued. According to this decree, the value of the permissible value for noise level \(LA_{eq}\) from road and rail traffic for residential areas during the day and evening should not exceed 50 dB(A) and 45 dB(A) during the night. For areas around transport communication (100 m from the axis of the traffic communication) for road transport, it is 60 dB(A) during the day and evening and 50 dB(A) during the night and for railway transport, it is 60 dB(A) during the day and evening and 55 dB(A) during the night [10]. The construction and improvement of road infrastructure in Slovakia is currently affected by the amount of state funds. One of the cost components is the cost of noise abatement measures as noise significantly affects human health as well as the value of the affected area [11]. These harmful acoustic effects on humans can be reduced by designing passive noise protection devices, among them noise barriers [12]. The history of building noise barriers dates back to the middle of the 20 th century, when the first noise barriers were built in the United States, protecting the population from road traffic noise [13]. The first noise barriers were constructed as self-supporting monolithic walls with a mostly smooth surface. The visual impact of these walls was often neglected, and the walls mostly did not fit into the surrounding environment. Over time, requirements also began to be placed on the walls in terms of their aesthetic and architectural design, and segmented walls began to be built.