Acoustic impact on bridges

Abstract

The paper analyzes the influence of various factors on the level of acoustic impact during the passage of trains on bridges with span structures made of various materials. In the course of the work, a qualitative analysis of the measurement conditions (type of rolling stock, bridge structure design, acoustic conditions, etc.) and factors (span type, design of the cushion layer, distance from the noise source, climatic factors) affecting the maximum or equivalent sound level was carried out. Direct measurements of the maximum and equivalent sound levels on bridges with different spans were made. When the freight train passes, the greatest acoustic impact occurs on metal spans, the maximum sound level on which is recorded at a distance of 6.5 m from the track axis up to 99 dBA. If all else being equal – the speed of the train, its length, irregularities on the surface of the rails and wheels of the rolling stock, natural, climatic and external acoustic conditions, the most significant influence on the level of acoustic impact has a constructive solution of bridge structures – the type of span structure and the material from which it is made, as well as the damping capacity of the cushion layer between the plates of the ballastless bridge deck (BBD) and the longitudinal beams of the spans. The least acoustic impact on the environment is exerted by reinforced concrete and all-composite spans, which determine the lower sound level in comparison with metal spans by 6-8 dBA. Laying an elastic cushion layer between BBD slabs and longitudinal beams reduces the acoustic impact on metal spans by up to 2-3 dBA.