| 1. |
- Forssén, Jens, 1968, et al.
(författare)
-
Porous ground, crops, and buried resonators
- 2014
-
Ingår i: Environmental Methods for Transport Noise Reduction. - : CRC Press. - 9781482288773 ; , s. 153-176
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Transport noise travelling near to naturally occurring porous ground surfaces, such as grassland, is reduced at frequencies relevant to noise control as the result of interference between direct and groundreflected sound known as the ground effect. Although it is observed frequently that different types of naturally occurring ground surfaces give rise to different ground effects, little thought has been given to deliberately choosing ground to give an improved noise reduction. In this chapter, results of calculations and measurements are provided that can inform this choice. Dense vegetation, in the form of ground cover or crops, contributes to ground effect as a result of the penetration of roots into soil and adds extra attenuation due to scattering by leaves and stems. Calculations are provided that suggest the potential usefulness for noise control of certain combinations of ground and crops. Experiments and calculations are reported showing that ground that is otherwise acoustically hard, such as nonporous asphalt or concrete, can be altered to be more effective for noise reduction by being made porous or by inserting porous strips or patches composed, for example, from gravel. Porous asphalt road surfaces are used to reduce both noise generation and propagation from road–tyre interaction. Their effectiveness for reducing traffic noise can be increased by burying preformed resonating chambers. Resonators also can be buried in hard or porous ground to reduce noise. Laboratory data and predictions are presented that demonstrate the usefulness of this method.
|
|
| 2. |
- Forssén, Jens, 1968, et al.
(författare)
-
Toolbox from the EC FP7 HOSANNA project for the reduction of road and rail traffic noise in the outdoor environment
- 2014
-
Ingår i: Transport Research Arena 2014, Paris, France. ; , s. 10-
-
Konferensbidrag (refereegranskat)abstract
- This paper offers a brief overview of innovative methods for road and rail traffic noise reduction between sourceand receiver. These include using new barrier designs, planting of trees, treatments of ground and road surfacesand greening of building façades and roofs using natural materials, like vegetation, soil and other substrates incombination with recycled materials and artificial elements. The abatements are assessed in terms of numericallypredicted sound level reductions, perceptual effects and cost–benefit analysis. Useful reductions of noise fromurban roads and tramways are predicted for 1-m-high urban noise barriers and these are increased by addinginter-lane barriers. A 3 m wide 0.3 m high lattice ground treatment, a carefully planted 15-m-wide tree belt andreplacing 50 m of paved areas by grassland are predicted to give similar reductions. Tree belts are shown to bevery cost-effective and combining tall barriers with a row of trees reduces the negative impact of wind. Greenroofs may significantly reduce the noise at the quiet side of buildings.
|
|
| 3. |
- Forssén, Jens, 1968, et al.
(författare)
-
Åtgärder i utomhusmiljön för att minska buller från väg- och tågtrafik – resultat från EU-projektet HOSANNA
- 2013
-
Ingår i: LjudBladet, Svenska akustiska sällskapet. - 1403-2317. ; 3, s. 16-28
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Denna artikel ger en kort översikt av bulleråtgärder, resulterande från EU-projektet HOSANNA, för minskning av buller från väg- och spårtrafik under ljudets utbredning. Dessa verktyg inkluderar användning av ny skärmdesign, plantering av träd, förbättringar av mark- och vägytor samt vegetation på byggnadsfasader och tak, med hjälp av naturmaterial, såsom vegetation, jord och andra substrat i kombination med återvunnet material och artificiella element. De akustiska insättningsdämpningarna bedöms genom numeriska beräkningar, perceptuella effekter och kostnadsnyttoanalys. En betydande minskning av buller från väg- och spårtrafik förutsägs för ett 1-m-högt urbant bullerskydd. Detta kan förbättras, upp till ca 10 dB insättningsdämpning, genom att placera ytterligare skydd mellan körfälten. Ett 3 m brett och 0,3 m högt rutnät, ett omsorgsfullt planterat 15 m brett trädbälte samt att ersätta 50 meter asfalterad mark med gräsmark förutspås ge bullerminskningar om 5–8 dB, medan användning av fasadvegetation och gröna tak kan minska nivån på innergårdar med upp till ca 4 respektive 7 dB. Trädbälten visar sig vara mycket kostnadseffektiva och kombinationer av höga skärmar med en rad av träd minskar de negativa effekterna av vind på bullerskärmars insättningsdämpning. Gröna tak kan minska bullret på den tysta sidan av byggnader.
|
|
| 4. |
- Nilsson, Mats, et al.
(författare)
-
NOVEL SOLUTIONS FOR QUIETER AND GREENER CITIES
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This brochure summarizes the main findings of the research project “HOlistic and Sustainable Abatement of Noise by optimized combinations of Natural and Artificial means” (HOSANNA). The project aimed to develop a toolbox for reducing road and rail traffic noise in outdoor environments by the optimal use of vegetation, soil, other natural materials and recycled materials in combination with artificial elements.
|
|
| 5. |
- Schubert, Stefan, et al.
(författare)
-
Influence of the tyre impedance on CPX level used to evaluate tyre/road noise
- 2016
-
Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future.
-
Konferensbidrag (refereegranskat)abstract
- For traffic noise studies CPX measurements are used to evaluate the noise-reduction of a road surface.CPX measurements as described in ISO/DIS 11819-2 are carried out at microphone positions close to predefined tyres at constant speed. The dominant CPX sound source is the tyre’s rolling noise as a result of tyre/road interaction, which - apart from the acoustic properties of the road surface - is mainly determined by the properties of the tyre.To ensure continuous quality and comparability of CPX measurements, the variation of acoustically relevant properties of the reference tyres must be taken into account to reduce measurement uncertainties. Thus, to ensure comparability, the standard ISO/TS 11819-3 specifies Shore hardness values to be checked at regular intervals and compared with normative values. According to our experience in CPX-measurements, determining the Shore hardness of the tyres is not sufficient to describe the reference tyres’ acoustically relevant properties. So, as an additional parameter the mechanical impedance of different reference tyres was measured and compared to their Shore hardness and CPX levels on different road surfaces.Based on these results, conclusions are drawn about the usability of the tyre impedance to increase the quality and comparability of CPX measurements.
|
|
| 6. |
- Winroth, Julia, 1981, et al.
(författare)
-
Investigating generation mechanisms of tyre/road noise by speed exponent analysis
- 2017
-
Ingår i: Applied Acoustics. - : Elsevier BV. - 0003-682X .- 1872-910X. ; 115, s. 101-108
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to clarify the influence of air-pumping related noise sources on typical tyre/road noise. The aim is to increase the understanding of noise generation mechanisms and catalyse the development of existing tyre/road noise simulation tools. The speed dependency of measured and simulated tyre/road noise is analysed and the results show that a large part of the noise can be explained by a high speed exponent traditionally connected with air-pumping mechanisms. Surprisingly, this is also the case for rough road surfaces which are expected to mainly generate noise by tyre vibrations. It is also found that vehicle wind noise may have a strong influence on the pass-by noise and care must be taken when analysing measurement data of quiet tyre/road combinations. Even simulated tyre/road noise shows higher speed exponents than what is anticipated without the inclusion of any type of air-pumping mechanism in the model. It is concluded that it is unfeasible to separate noise created by tyre vibrations from noise created by air-pumping with a speed exponent analysis due to the overlap in the speed exponents connected with the different generation mechanisms.
|
|
| 7. |
- Winroth, Julia, 1981, et al.
(författare)
-
Separating the contributions from air-pumping and tyre vibrations by speed dependency analysis of tyre/road noise
- 2016
-
Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future.
-
Konferensbidrag (refereegranskat)abstract
- Traditionally tyre/road noise has been divided into low-mid frequency noise caused by tyre vibrations and high frequency noise caused by various air flow related mechanisms, "air-pumping". It has also been assumed that these two processes grow in importance with different (vehicle) speed exponents. The purpose with this work is to investigate how to extract the different noise sources by a speed exponent analysis. Such analysis tool would e.g. indicate under which circumstances it is necessary to include air flow related sources in a tyre/road noise prediction model. The results show that it is possible to extract components of tyre/road noise that grow with the speed to the power of two and four. Expecting these contributions to be connected to tyre vibrations and air flow related source mechanisms respectively, it is found that the latter are present at surprisingly low frequencies. In addition, modelled results, only taking into account noise created by tyre vibrations, also show speed exponents larger than two. It is concluded that tyre vibrations can generate noise with a range of speed exponents making it futile to separate the two main tyre/road noise source mechanisms by a speed exponent analysis.
|
|
