Possibilities of Evaluating the Effectiveness of Noise Barriers in Slovakia

Abstract

This paper presents environmental acute problems from increasing noise levels caused by automobile and rail transport. Noise barriers are considered to be an effective element in reducing noise in densely populated urban areas. However, do these barriers have the correct height, shape, material design, and construction? In the materials and methods, the basic characteristics of noise barrier, sound absorption, and sound insulation are described. Further, measurement methods of the insertion loss of outdoor noise barriers of all types using the direct and indirect method according to standard ISO 10847 and the Adrienne method according to standards EN 1793-5 and EN 1793-6 are presented. The measurement results of insertion loss of the selected noise barrier obtained by the indirect method showed a value of 19.1 dB(A) of insertion loss. This result was compared with simulation by our own software based on the CNOSSOS methodology, giving value of 19.6 dB(A), which is a good correlation. The Adrienne method was used for determination of the airborne sound insulation index of another noise barrier, giving a value of the single-number rating of the sound insulation of the barrier of 28 dB. In discussion, according to EN 1793-2, this value assigns an insulation index of category D3, which means that the barrier is high quality and has satisfactory airborne sound insulation. The advantages and disadvantages of both methods according to STN ISO 10847 and STN EN 1793-6 were discussed. We concluded that the main advantage of the method Adrienne—TN EN 1793-6 is that it can be used in situ under direct sound field conditions and can directly evaluate the sound insulation index of the whole barrier structure.

Vasúti közlekedés során keletkező zajok okainak és hatásainak elemzése

“… Infrastrúktúra fejlesztése és karbantartása: Az infrastrúktúra állapötának javítása, példáúl a sínek cseréje, keresztaljak javítása és a pályatörzs karbantartása hatékönyan csökkentheti a zajkiböcsátást [12], [13]. A költségigény ezekben az esetekben általában magasabb lehet, különösen ha nagy területekre és hösszú vasútvönalakra terjednek ki a fejlesztések.…”

Approaches for Noise Barrier Effectiveness Evaluation Based on In Situ “Insertion Loss” Determination

“…The use of artificial noise sources is infrequent and is used only when it is not possible to use traffic noise in equivalent conditions. This artificial point source may be based on a loudspeaker that reproduces traffic noise [20] or a regulated artificial signal such as pink noise [43].…”

“…In most studies, microphones are placed at regular distances from the barrier (5, 10, 15 m), or corresponding to incremental doublings of the distance (e.g., 7.5, 15, 30 m) [42,44]. Some studies determine IL levels by placing a single microphone in the near field behind the barrier, at distances of 1-5 m [20,43,45,46]. The most common height for the microphone is 1.5 m, although there are studies that consider additional heights, which are similar to or higher than the barrier height (e.g., 2, 4, 6 m).…”

“…The duration of the measurements in studies based on the indirect method depends on the nature of the noise source. In the case of studies using an equivalent artificial noise source, the duration of measurements is usually short (such as 2 min) in accordance with the ISO standard [43]. In the case of road traffic noise, the period is usually long enough to ensure the representativeness of the spectrum of the traffic noise.…”

“…Attenuation values obtained in the near field, at distances from the barrier of 5-7 m, and heights above ground of 1.2-1.5 m, range between 7 and 10 dB(A) [20,42,[44][45][46]50]. Insertion Loss levels are higher at shorter distances from the barrier, such as 1 m [43]. The IL values at comparable greater distances from the barrier (20-30 m) tend to decrease to values of 3-5 dB(A) [40,42,44], although one study reports much higher attenuation levels of up to 10 dB(A) at intermediate distances (15 m) [51].…”