Holistic and sustainable abatement of noise by optimized combinations of natural and artificial means

Project Information

HOSANNA

Grant agreement ID: 234306

Project closed

Start date 1 November 2009

End date 30 April 2013

Funded under

• Specific Programme "Cooperation": Transport (including Aeronautics)

Total cost € 5 098 393,00

EU contribution € 3 900 000,00

Coordinated by

CHALMERS TEKNISKA HOGSKOLA AB
Sweden

Final Report Summary - HOSANNA (Holistic and sustainable abatement of noise by optimized combinations of natural and artificial means)

Executive Summary:
The project presents methods to reduce noise from surface transport, by exploiting green areas and surfaces in urban and rural environments and inserting natural and artificial elements. A majority of the EU population is estimated to be exposed to outdoor road traffic noise levels above the threshold suggested by WHO for onset of negative health effects. At the same time, road and rail traffic are expected to steadily increase, and the source strength is not expected to significantly decrease within the nearest decades. Although indoor noise reduction can be achieved using conventional facade insulation and closed windows, it is a challenge to protect the outdoor sound environment from excessive surface transport noise. If both the outdoor sound environment and the access to green areas are poor, public health may be threatened in the long-term. Hence, methods of reduction are needed during the propagation of sound from source to receiver.

The central outcome of the project is a toolbox of suggested noise mitigation methods. The methods, which are substantiated by real life field cases, are being presented in the form of a brochure, a handbook and tables for engineering use, in addition to the publically available technical reports of the project and the scientific publications as result of the research work. The methods aim at an increased use of vegetation, through greening roofs, façades and other urban and rural surfaces, innovative vegetated barriers, recycled materials and new treatments of the ground surface. Thereby we suggest moving beyond the current tools of traffic noise reducing measures. Furthermore, the project presents perceived improvement of the sonic environment as well as good cost-benefit ratios for many of the suggested noise mitigation methods.

Our results show that 1 m high acoustically absorbing barriers with vegetation can provide an excess attenuation of at least 8 dBA for a 1.5 m high receiver and 6 dBA for a 4 m high receiver for typical urban road traffic noise situations (driving speed 50 km/h and a proportion of 5 % heavy vehicles). By adding inter-lane barriers, reduction of noise from road vehicles as well as from trams can reach more than 10 dBA. However, the perceived improvement is shown to be comparably somewhat smaller, concluded to arise from the relative increase in low-frequency noise. The low vegetated barriers are also estimated to be cost effective, i.e. showing a benefit-to-cost ratio above 1. Concerning use of trees, studies for a 15-m deep belt show effects exceeding 5 dBA when planting schemes are optimized, as well as very good cost-benefit ratios. Also, the negative effect of wind on classical noise barrier performance can be limited by using the canopy of trees as windbreak, especially for motorway situations in open field. We show that by introducing particular types of grassland, an improvement by 2–3 dBA can be achieved compared with typical grass covers, and thereby an 8 dBA reduction compared with acoustically-hard ground, for a propagation distance of 50 m. It is also shown that laying tracks in grass can reduce tram noise by 3 dBA compared to having tracks embedded in asphalt, with a comparably somewhat larger perceived improvement. Roughening elements on otherwise smooth hard ground has been shown useful for reduction of noise from surface transport as well as the use of low (0.3 m tall), parallel walls or lattice arrangements, also estimated to have good cost benefit ratios. The acoustical properties of plants and substrates have been measured and modelled and calculations have been made of the effect of green roofs on noise propagation to courtyards as well as of the effect of green façades in street areas. For noise propagation to an inner yard, the effect of greening the roof is about 3 dBA for typical configurations with a flat roof and up to 8 dBA for a ridged roof.

Project Context and Objectives:
The project results in a toolbox for the reduction of road and rail traffic noise in the outdoor environment.

HOSANNA is a collaborative Project under the Seventh Framework Programme, Theme 7, Sustainable Surface Transport.

The project started in November 2009 ran until April 2013. The project was coordinated by Chalmers University of Technology, Gothenburg, Sweden. (All partners are shown in Figure 1.)

Noise pollution is a major environmental problem within the European Union. Outside our homes a majority of the population is estimated to be exposed to road traffic noise levels above WHO’s threshold for onset of negative health effects. The corresponding number for rail traffic noise is lower but still warrants action. The social costs of traffic noise are significant. In a recent WHO report it was stated that "among environmental factors in Europe, environmental noise leads to a disease burden that is second in magnitude only to that from air pollution". At the same time, road and rail traffic are expected to steadily increase, and the source strength is not expected to significantly decrease within the nearest decades. Hence, a reduction is needed that works during the propagation from source to listener. Whereas the indoor noise due to traffic can be reduced to a sufficiently low level for a good sound environment using conventional facade insulation and closed windows, the outdoor sound environment is more difficult to protect.

Current tools for noise abatement may involve tall and acoustically hard noise barriers, road traffic speed limits and porous asphalt road surfaces. With the central project outcomes we aim at moving forward the state of art, using greening of buildings as well as vegetation on other urban and rural surfaces, innovative barriers including recycled materials, and new treatments of the ground and of the road surface, beyond the current tools of traditional, tall barriers, speed limits and porous asphalt surfaces. The dissemination is made, in addition to the scientific publications in journals and conference proceedings, through a summary brochure presented at workshops and a handbook that is contracted with a publisher. Furthermore, a set of engineering tools in the form of tabulated insertion losses as well as the technical reports of the project are available through the project website.

If the outdoor sound environment and the access to green areas is poor it may threaten the public health in a long-term perspective. The costs of having green areas and surfaces in urban and rural environments are well accepted and established without the noise issue being considered. The main concept here is that exploiting these green areas and surfaces and at the same time minimize the noise impact on citizens of Europe leads to a better use of resources.

The overall objectives of HOSANNA are:
• To develop new, powerful and sustainable abatement methods for noise reduction, based on natural means in combination with artificial means;
• To show by full-scale evaluation that the abatement methods work;
• To develop prediction methods applicable to analysis and design of the developed abatements;
• To make available simplified models applicable to the developed abatements, which can be used in engineering noise mapping software and make our innovative approaches show in reporting of strategic maps and action plans to the EU;
• To make available assessment methods for the perceived improvement of the sonic environment and reduced noise annoyance;
• To show the cost benefit of the resulting abatement methods, including the positive effect on urban air quality and CO2 neutrality;
• To disseminate the results to the user community (consultants, local authorities and planners), mainly by the publication of our Handbook.

The work was divided into a set of workpackages. In four workpackages, research and development work is carried out on the different themes of noise abatement approaches: innovative barriers with natural and recycled materials; trees, shrubs and bushes; ground treatments; and greening of façades and roofs of buildings. In a fifth workpackage, combinations of the different abatement methods are modelled and evaluated, both perceptually and in terms if noise reduction in decibel, partly using field studies. The additional workpackages are on project coordination, cost benefit analysis and dissemination (where the Handbook and seminars are planned).

Results show that acoustically absorbing barriers of low height (about 1 m) can provide an excess attenuation of at least 8 dBA for a 1.5 m high receiver and 6 dBA for a 4 m high receiver for urban road traffic noise situations (driving speed 50 km/h and a proportion of 5 % heavy vehicles). By adding inter-lane barriers, noise from road vehicles as well as from trams can be reduced by more than 10 dBA. Concerning use of trees, studies for a 15 m thick belt of show effects of about 3 dBA. For ground treatments, it has been shown that by selecting better types of grass ground, an improvement by 2–3 dBA can be achieved compared with typical grass covers, exemplified with an 8 dBA reduction for a propagation distance of 50 m. Also, roughening elements on otherwise smooth hard ground has been shown useful for reduction of noise from surface transport as well as use of low, parallel walls (0.3 m tall). The acoustic properties of plants and substrates have been modelled using measurement results and calculations have been made of the effect of green roofs on noise propagation to courtyards as well as of the effect of green façades in street areas. For noise propagation to an inner yard, the effect of greening the roof is about 3 dBA for typical configurations with a flat roof and up to 8 dBA for a ridged roof.

The first field study concerned an urban road, Quai Fulchiron, in Lyon, France (see Figure 2). A low, vegetated barrier was designed and built followed by a full two-week measurement campaign. Simultaneous measurements were carried out on different sections of the street, with and without the barrier installed. Questionnaires distributed to a random sample of passers by were used in order to assess the impact on the perceived soundscape. In parallel, binaural recordings with dummy heads as well as ambisonic recordings were carried. The recordings have been used in laboratory listening tests to assess the perceived improvement. The other field studies include effect of: resonators in motorway road surface (site near Berlin), grass ground for a tramway line (site in Grenoble), hedges (sites in Wolfratshausen, Grenoble, Milton-Keynes and Bradford), tall vegetated noise barriers (sites in Wolfratshausen and Cannes), earth berm along a motorway (site near Ghent) and green roof (in Eindhoven).

The project website (www.greener-cities.eu) has public pages that describe the project, and a download area for public deliverables, as well as an internal upload and download page. A screen capture of the website is displayed below (Figure 3).

Project Results:
Objectives of the project

Below are listed the objectives of the project for the full duration.

The overall objectives of HOSANNA are:
1) To develop new, powerful and sustainable abatement methods for noise reduction, based on natural means in combination with artificial means
2) To show by full-scale evaluation that the abatement methods work
3) To develop prediction methods applicable to analysis and design of the developed abatements
4) To make available simplified models applicable to the developed abatements, which can be used in engineering noise mapping software and make our innovative approaches show in reporting of strategic maps and action plans to the EU
5) To make available assessment methods for the perceived improvement of the sonic environment and reduced noise annoyance
6) To show the cost benefit of the resulting abatement methods, including the positive effect on urban air quality and CO2 neutrality
7) To disseminate the results to the user community (consultants, local authorities and planners), mainly by producing, making available and presenting a Handbook

The Quantitative acoustic objectives, with fulfilment demonstrated either by full-scale measurements or by validated models are to produce global solutions (combining designs for ground, barriers, vegetation, facades, etc.) which lead to a minimum noise abatement of:
8) 6 dBA in urban areas, at a 4 m high receiver location alongside a given surface transport corridor, compared to an untreated situation
9) 10 dBA in urban areas, at a 1.5 m high receiver location alongside a given surface transport corridor, compared to an untreated situation
10) 4 dBA in rural areas, at a 4 m high receiver location alongside a given surface transport corridor, compared to a straight barrier situation
11) 6 dBA in rural areas, at a 1.5 m high receiver location alongside a given surface transport corridor, compared to a straight barrier situation

Further quantitative objectives:
12) To develop prediction methods applicable to analysis and design of the developed abatements that allow predicting the desired effect to within 2 dBA under well controlled situations.
13) The abatement methods for noise reduction shall lead to a reduction in LAeq of at least the same amount as traditional means, but with the additional benefit that:
i. Perceptual effects are improved
ii. Total cost over full lifetime (estimated using life cycle analysis) is lower
iii. Non-acoustic appreciation of the living environment is improved
iv. The CO2 balance is at least neutral

For the first reporting period (18 months), work was started to fulfil objectives 1–4 as well as 8–13. Objectives 1–3 were achieved by M36. For objective 4, achieved by M42, simplified models have been delivered in form of results tables, accessible via the project website.

About the targeted noise reductions (objectives 8–11), a key deliverable report D2.3 has concluded that the objectives have been achieved. This report together with the other reports of the technical workpackages (WPs 2–5) give at hand that the aimed scope of the prediction methods (objective 12) also has been met. Concerning objective 13, the key deliverables are D6.3 and D7.4. It is concluded in D7.4 that: (i) perceptual effects are improved; (ii) the cost-benefit ratio may be very favourable for some mitigations, including low lifetime costs; and (iv) the CO2 balance is neutral or better for some mitigations, e.g. tree belts. It is concluded in both D7.4 and D6.3 that (iii) that the non-acoustic appreciation of the living environment is improved.

The work directly linked to objectives 5–7 were started in the second period and are now finalized. The work on perception and annoyance (objective 5) is reported in deliverable 6.3 where e.g. relative content of low frequency noise, median A-weighted sound pressure level (LA50) and number noticed events are concluded to constitute a viable supplement to indicators for assessing the sound environment. The cost benefit analysis (objective 6) is reported in deliverable 7.4. High cost-to-benefit ratios were shown for a number of suggested mitigations, however it is estimated that only the measures with tree belts are CO2 neutral and that the effect on air quality is small. About the dissemination (objective 7), the workshops have been carried out (Stockholm, Lyon, London, Munich), as reported in deliverables 8.4-8.7. The summary brochure was ready as a printed paper-version in January 2013 and is also downloadable from the project website. The work for the handbook is reported in deliverable 8.3 where the contents, chapter structure and the contract with the publisher are described. Publication is planned for autumn 2013.
The project has reached its objectives.


Summary of S&T results/foregrounds

Mainly, the work has been running according to plan and there is no deviation from the planned milestones or deliverables. Concerning the scientific and technological work, it has been carried out in what we call the technical workpackages (WPs 2–5), on the different themes of noise abatement approaches: innovative barriers with natural and recycled materials (WP2); trees, shrubs and bushes (WP3); ground treatments (WP4); and greening of façades and roofs of buildings (WP5). In workpackage 6, the different abatement methods are globally modelled and evaluated, both perceptually and in terms if noise reduction in decibel. The field studies of WP6 are partially aided by virtual means. In WP7 the cost benefit analysis (CBA) is made. The dissemination work is carried out in WP8, with workshops, a summary brochure and a handbook.

In WP2, calculations have been carried out to study different types of: sources (urban street, motorway, tramway, freight trains, high speed trains); dwellings (city centre/street canyon, other urban, rural); and topography (flat, depressed or embanked infrastructure as well as infrastructure on bridge). Main results in terms of potential noise reduction at a height between 1.5 to 4 m above ground are as follows:
o For low height barriers (gabions, vegetated, earth berms): 3-12 dBA for an urban road and 9-15 dBA for a tramway at a distance of 2-50 m,
o For light vegetated barriers along bridges: up to 5 dBA below a 4 lane road traffic bridge, up to 15 dBA below a tramway bridge,
o Vegetated barrier caps (max cap size: 1.2 m; min barrier height: 4 m): 6-14 dBA at a distance of 1-20 m compared with a straight barrier uncapped of same overall height,
o Eart berms with strongly non-flat surfaces: up to 5 dBA compared with a smooth trapezoidal berm at a distance 1-50 m.
All tasks of WP2 are finalized.

Concerning WP3 and the numerical modelling of a tree belt above a finite impedance ground surface, it was shown that the ground effect could be treated separately from the tree scattering. This can be considered as an important break-through, and allowed calculating in a much faster way many configurations. In addition, estimating the effect of finite length tree belts became possible, increasing realism of the simulations. The many simulations performed showed that a good choice of planting scheme could make a difference of more than 3.5 dBA, at a biomass filling-fraction of 1.5 %, reaching 5 dBA noise reduction in total compared with hard ground. Also at lower filling fractions, a good choice of planting scheme makes sense and should be considered. In addition, a forest strip was shown to have a positive influence in reducing negative effects of night-time ground based temperature inversion. Also, important results and conclusions have been attained concerning noise barriers in downwind conditions, limiting the negative wind effect by using the canopy of trees as windbreak. For the work in Task 3.4 about optimization of artificial refraction, the novel concept of an upward refracting barrier-like device has been developed and studied numerically. All tasks of WP3 are finalized. A concluding work on the acoustic insertion loss of hedges has been made, based on a set of independent measurements made within the project, and reported in an added deliverable (D3.5). It shows that the noise shielding is usually limited to about 2 dBA for a rather dense hedge with thickness of at least 2 m, for a realistic road traffic conditions at low vehicle speeds. All tasks of WP3 are finalized.

In WP4, numerical predictions have shown that a series of wall clusters each of which has a fractal height pattern (maximum height 0.3 m) and an overall width of at least 16 m can give up to 2.5 dBA additional reduction compared with a regularly spaced array of uniform parallel low walls with the same overall width. Calculations for a 2-lane urban road and a 1.5 m high receiver indicate that a 0.3 m high lattice (a 3D roughness with inner square cell dimension of 0.2 m) arrangement is more efficient than the same width of low parallel walls and gives on the order of 4 dB reduction from 1.5 m width and 10 dB from a 12 m wide arrangement. Furthermore, calculations suggest that replacing acoustically hard ground by a particular (low compaction) kind of soft ground starting 2.5 m from the edge of a 2-lane urban road and continuing to 50 m from the road can result in a reduction of about 9 dB at a 1.5 m high receiver and 3 dB at a 4 m high receiver. Predictions indicate that there is little noise reduction advantage in dividing the soft ground into strips or patches compared with a single soft ground area. In addition, a model to predict the insertion loss of an array of resonators has been developed and validated against laboratory measurements (CTH), and the insertion loss of a roadside field of resonators has been calculated. Also, calculations to determine the absorption coefficient of combinations of porous media and resonators have been carried out, for use in road surfaces (MBBM). Concerning the possible influence of meteorological conditions for ground treatments, calculations using 2D-FDTD, 3D-PSTD and 2D-PE have been used. It is found that insertion losses due to recessed ground treatments starting closer to the source than raised ones are less affected by downward refraction. All tasks of WP4 are finalized.

To study the effects of vegetation on facades and roofs, in WP5, standard configurations were developed by CSTB, CTH, IBBT and USFD and agreed by the consortium. Numerical comparisons were made for a series of configurations. Scale model measurements have been made by HYU corresponding to the standard configurations, and the effects of vegetation have been examined systematically. Results show that façade treatments in urban canyons are limited to 2-3 dBA noise reduction in realistic situations. Roof treatments, on the other hand, may give greater effect for courtyards, where e.g. low vegetated barriers in the roof edges of the separating building are predicted to give 3 dBA and vegetation of angled roofs may give up to 8 dBA noise reduction compared to a rigid roof. All tasks of WP5 are finalized.

In WP6, task 6.1 on case studies, at Quai Fulchiron, Lyon, an experimental low barrier was designed, built and extensively measured. Binaural recordings and questionnaires were made for the purpose of perceptual evaluation in WP6.3. The results of this campaign were analysed and used in WP6.2 for validation purposes of the holistic prediction tool. The efficiency of the low barrier of the case study was approximately 4 dBA in terms of LAeq and 6 dBA in terms of LAmax. Simulations in WP6.2 show that optimal design of the barrier might have improved the results, by circa 2 dB. As it turned out to not be possible to repeat the Lyon experimental setup at other locations, for other mitigations, smaller test cases were sought in order to demonstrate the efficiency of mitigation on existing or ongoing projects. In and near Berlin, measurements were carried out at 3 sites, selected in order to characterize 5 different road surfaces. The Zossen site was selected to characterize the reference road surface as defined used in the NMPB-2008 and Harmonoise methods. On the motorway, both porous asphalt and an experimental road surface incorporating resonators were measured. At the Gneissenaustrasse site, two different low noise surfaces were measured under urban traffic conditions. At all sites, both CPX and SPB measurements as well as binaural recordings were made. In Grenoble, measurements were made near a tramway line in order to evaluate the effects of soft ground on the radiation of wheel/track contact noise. It was found that laying tracks in grass reduces noise by 3 dBA compared to tracks embedded in asphalt. In Wolfratshausen, a hedge separating a private garden from the nearby road has been removed and replaced by a vegetated barrier. Measurements were made before and after removal the hedge and after installing the green wall. The effect of the hedge was found to be approximately 1 dBA; the effect of the wall, more than 10 dBA at ground level. Monitoring of long term noise levels took place in Belgium before and after installing a large earth berm nearby a motorway with dense traffic, with effects up to 10 dBA. In Eindhoven, measurements were made before and after installing vegetated roofs on a new building block, indicating 2–3 dBA reduction of outside traffic noise.

Concerning task 6.2 about the holistic prediction tool, since standard prediction methods have limited accuracy when it comes to innovative mitigations (e.g. low barriers or special ground treatments are simply ignored in the ISO 9613-2 standard), the use of extensions allows the software tool to combine standard prediction (engineering) methods with more elaborate numerical calculation schemes (BEM, PE, FDTD, etc.). The extensions make use of pre-calculated numerical results on predefined source/receiver grids and interpolation in order to estimate the effects of the innovative mitigation along different propagation paths in a complex environment. The extension technique has been validated using numerical results provided by WP2, 3 and 4 as well as data from the Lyon Quai Fulchiron case study. Digital models have been built for the Lyon Quai Fulchiron and Berlin Gneisenaustrasse sites. The OASIS software has been used to predict the effect of combined solutions (i.e. low barriers and low noise road surfaces) in urban conditions. The QUIESST project has reused the HOSANNA extension approach to evaluate the overall efficiency of optimised barriers. For the purpose of this evaluation, a set of fictive but representative built-up sites has been created. On each site, noise levels are calculated for a large number of receiver positions, both at ground level and in front of the building façades. The CNOSSOS-EU methodology is used to link receivers to numbers of exposed populations. The QUIESST methodology and data sets are used for a cost benefit analysis of WP7. The tool was adapted in order to take into account alternative and combined solutions as proposed by the HOSANNA project and to provide output data sets suitable for CBA.

In task 6.3 the innovative mitigations proposed by the technical WPs are linked to perceptual evaluations using sound synthesis, i.e. auralization. The auralization technique developed by CSTB has been adapted, fine-tuned and validated, based on experimental data from the Lyon and Berlin test cases. Post-processing tools have been developed in order to simulate the different measurement methods and to produce numerical results directly comparable to the data. The auralization handles rolling and propulsion noise separately and the data from the Berlin test case have been integrated in order to simulate the effect of low and ultra-low road surfaces. For the Lyon and Gneisenaustrasse cases, combined solutions based on low barriers and low noise surfaces have been simulated, allowing for reductions of maximum levels by up to 10 dBA. About the perceived effect of abatements, listening experiments have been conducted using binaural recordings from Lyon, Quai Fulchiron. The results complement those obtained in the questionnaire study. Further analyses of questionnaire data from Lyon, Quai Fulchiron was conducted with focus on correlation between acoustic measurements and various advanced as well as simplified soundscape quality indicators. Work has been conducted on applying advanced models for sound source identification (Notice-event-model) to predict questionnaire responses collected in the Quai Fulchiron-study. Further work in this subject would be of interest since the Quai Fulchiron case was dominated by road-traffic noise also after treatment, leaving little room for variation in perception of other sounds. Further conclusions from task 6.3 are as follows.
o Questionnaire responses among pedestrians showed that a low-height vegetated barrier erected close to a road may reduce road-traffic noise annoyance, and increase the overall quality of the sound environment by making it slightly calmer and slightly more pleasant. Psychoacoustic analyses relating questionnaire response to acoustic variables suggested that annoyance apart from being strongly related to overall level of the noise also was related to the relative proportion of low frequency noise. This is relevant for the evaluation of noise barriers which in addition to reducing the overall level also changes the spectral content of the noise by reducing high frequency noise more than low frequency noise at the shielded side of the barrier.
o A listening experiment with recordings behind and besides a low-height vegetated barrier erected close to a road showed that the barrier reduced annoyance of the traffic noise, and that this effect was well predicted by the associated reduction in A-weighted sound pressure level. However, there was a slight tendency for the annoyance reduction to be slightly less than would be expected from the reduction in A-weighted sound pressure level (SPL). This can partly be explained by the barrier’s lower reduction of low-frequency than high-frequency sounds. Loudness level is an alternative to A-weighted SPL that may better predict noise barrier’s annoyance reduction potential.
o The results of measurements and listening experiments suggested that replacing hard ground with soft ground (grass) between tramways and listeners will reduce sound pressure level with around 3 dB at 7 m distance, and that corresponding effect on perceived annoyance may be slightly greater due to perceptual changes related to the change in spectral composition of the noise.
o In a soundwalk study with a panel of residents, soundscape clearly separated the different locations in a meaningful way in terms of sound source identification, perceived pleasantness and eventfulness, and soundscape quality. Assessment of perceived overall quality was found to be closer linked to perceived visual than to perceived auditory quality of the locations. This shows the importance of considering visual aspects when introducing noise mitigation methods.
o Results of listening experiment showed that adding sounds from fountains or bird song to soundscapes may reduce loudness of road traffic noise of low temporal variability (freeway, major roads at distance), presumably by attracting attention to the more variable sounds (bird song, fountain). Moreover, addition of water or bird sounds may increase the overall pleasantness of soundscapes by increasing the proportion of “wanted” sounds.
o Analyses of acoustic soundscape indicators in relation to the amount of visible greenery verified that increasing greenery increases the probability to hear natural sounds in an environment. Interestingly, the results suggested that such an effect may be expected already at small percentages of natural greenery (about 10 %).
o Indicators of soundscape quality beyond the LAeq include the median A-weighted sound pressure level (LA50), music-likeness (ML1, capturing pleasant temporal variation), centre of gravity (log10[G], related to the proportion of low-frequency noise) and the number of events exceeding LA50 with 3 dBA for at least 3 seconds (Ncn). In addition, the proportion of natural, human and traffic noise sources in the soundscape may be evaluated through listening tests, or using automated source recognition software (under development).
All tasks of WP6 are finalized.

Within the work of WP7, Monte Carlo simulations have been fully integrated with the Cost-Benefit Analyses. Statistical, measurement, and assessment errors are incorporated into the framework and the tool has been applied to green roofs and vegetated facades. A facility for running different alternatives and compare them in one and the same run has been implemented, allowing the direct comparison of competing alternatives. The complete analysis of abatements from technical WPs is reported in D7.4 benefiting from an impact situation suggested by the QUIESST project. Deliverable 7.4 presents economic analyses of green roofs, green façades, a vegetated low barrier, traditional noise barriers with and without a vegetated cap, ground surface treatments, and the use of vegetation in the form of a tree belt. In addition to porous asphalt showing a good economic performance, novel measures developed and refined as part of the project have the potential of not only being cost efficient (that is provide more benefits than costs), but in some cases seem to be robustly efficient (providing benefits more than twice the cost). The main explanations for measures having good economic efficiency are that they are relatively inexpensive (lattice barriers, tree belts), or provide high acoustic benefits (porous asphalt with resonators), or provide additional amenity/aesthetic benefits (vegetated facades). Economic analyses of a combined measure have also been made, where brick lattices are used in combination with porous asphalt with or without buried resonators. By combining measures, it is possible to attain environmental noise limits, or improve the neighbourhood soundscape more than what is possible with measures targeting sources only. For several measures (vegetated façades, low vegetated barriers, and tree belts) aesthetics or amenity benefits beyond the soundscape improvement are concluded to play an important role in making the measures robustly efficient. The input data contains uncertainties. However, Monte Carlo results suggest that even after a potential downward adjustment of the valuation of aesthetic benefits, aesthetics will still remain important. If the results from the economic analyses presented here hold up in follow-up studies, the role of local noise abatement efforts targeting noise propagation cannot be ruled out on economic grounds. They will then have their place both as a supplement to noise reduction at the source, and as part of more holistically motivated urban improvement plans. All tasks of WP7 are finalized.


Details of work progress in WPs 2–7

WP2

Progress towards objectives and significant results

Objective
To carry out a state of the art study of acoustical models dedicated to barriers with vegetation, also considering recycled materials
To produce and apply porous acoustic products made from a range of recycled polymeric and elastomeric industrial waste using a novel extrusion process

Associated tasks and deliverables
T2.1: State of the art of experience and models. Make an inventory of vegetated shielding solutions and recycled porous materials as well as state-of-art description of models for outdoor sound propagation and acoustical properties of materials
D2.1: State of the art report

Progress and Results
A complete state of the art has been carried out including:
- An inventory of existing or idealized solutions,
- An inventory of existing recycle porous materials,
- A state of the art of sound propagation models,
- A state of the art of models for materials properties.
Porous acoustic products made from a range of recycled polymeric and elastomeric industrial waste have been produced and applied using a novel extrusion process.
Another class of material has been extruded using tyre shred residue for this project, the vibro-acoustic and thermal performance of this material is more superior compared to car dashboard crumb. Tyre shred residue consists of rubber crumb bonded to short fibres (fibres are the contaminate), it comes ground ready to use and has excellent potential for acoustic and thermal properties. It has been exemplified for use in combination with a green wall.
Porous products made using tyre shred residue have been characterised and show good vibro-acoustic and thermal properties compared with commercial products.

Objective
To characterise the acoustical properties of the recycled porous materials in the laboratory
To make choices of available prediction methods and to adapt them to each specific application

Associated tasks and deliverables
T2.2: Choice and adaptation of models. Numerical, analytical or hybrid models will be chosen and adapted to the applications of Task 2.3 i.e. to vegetated low barriers, combinations of barriers and shaped soil, and combinations of barriers and other surfaces with vegetation
D2.2: Intermediate report of Task 2.2

Progress and Results
A complete report on “choice and adaptation of models” (D2.2) has been written, including:
- Choice of existing models for sound propagation,
- Choice of ground impedance models,
- Selection of acoustical models for porous materials
- How to take meteorological effects into account,
- The adaptations of the BEM,
- The adaptations of the FDTD method.
A work on comparison/validation between models has also been performed in the framework of Task 2.2.
A paper on the modelling of sound propagation in thickets by means of a periodic BEM approach has been presented at Forum Acusticum 2011.

Objective
To characterise the acoustical shielding effect of plants
To carry out simulations of innovative vegetated barriers

Associated tasks and deliverables
T2.3: Application to innovations. The models of Task 2.2 will be used in the different applications (vegetated low barriers, combinations of barriers and shaped soil, and combinations of barriers and other surfaces with vegetation)
D2.3: Intermediate report of Task 2.3

Progress and Results
A comprehensive work has been carried out on the acoustical shielding effect of plants and hedges used in innovative barriers, including:
- Effects of plants on the acoustical properties of green wall cladding,
- Comparison of soil and plant specimen,
- Modelling the acoustical properties of plants and soil with the equivalent fluid model,
- Propagation through foliage
Many simulations have been carried out on:
- Conventional noise covered with a substrate,
- Effect of row of trees behind a noise barrier,
- Vegetated low barriers,
- Effect of inter-lane low barriers
- Low barrier made of gabions,
- Low height earth berms,
- Vegetated low barriers at the edge of urban bridges,
- Vegetated barrier caps,
- Complex shape earth berms,
- Sonic crystal barriers (rows of cylinders)
- Transversal wind effect on berms
Depending on the category of shielding solution studied, these calculations have been carried out for:
- Different types of sources: urban street, motorway, tramway, freight trains, high speed trains
- Different types of dwellings: city centre (canyon street), urban, rural
- Different types of topography: flat, depressed or embanked infrastructure, infrastructure on bridge.
The results of all these simulations are presented in a complete report on “Application to innovations” (D2.3).
It includes a section on “proposal for common cases” in order to homogenise the studied case within WPs2-5.
Participation in finding an experimental test site in Lyon for a low height vegetated prototype (Quai Fulchiron). Some performance calculations have also been carried out on that innovated vegetated barrier and design recommendations have been proposed to Canevaflor (Cane) and Acoucité (Acou) (see WP6).
Two papers on “Road traffic noise reduction by vegetated low noise barriers in urban streets” and “Optimization of low height sonic crystal noise barriers for tramway noise reduction” have been presented at EuroNoise 2012.
Two papers on “Acoustical performance of complex-shaped earth berms” and “Transport noise reduction by low height sonic crystal noise barriers” have been presented at Acoustics 2012 Nantes.
A paper on “Acoustic performance of gabions noise barriers: Numerical and experimental approaches“ has been published in Applied Acoustics, 74(1), 189–197 (2013)
A paper on “Acoustical Efficiency of a Sonic Crystal Assisted Noise Barrier “ has been published in Acta Acustica united with Acustica, 99(3), 399-409 (2013)

Objective
To make the analysis of all produced results and give recommendations

Associated tasks and deliverables
T2.4: Analysis and recommendations. The results from Task 2.3 are analysed, from which concluding recommendations are formulated on the use of vegetated low barriers, combinations of barriers and shaped soil, and combinations of barriers and other surfaces with vegetation
D2.4: Technical report with recommendations

Progress and Results
Main results in terms of potential noise reduction at a height between 1.5 to 4 m above ground are as follows:
- For low height barriers (gabions, vegetated, earth berms): 3-12 dBA for an urban road and 9-15 dBA for a tramway at a distance of 2-50 m,
- For light vegetated barriers along bridges: up to 5 dBA below a 4 lane road traffic bridge, up to 15 dBA below a tramway bridge
- For sonic crystal barriers: 3 dBA a t a distance of 10 m from the road
- Vegetated barrier caps (max cap size: 1.2 m; min barrier height: 4 m): 6-14 dBA at a distance of 1-20 m compared with a straight barrier uncapped of same overall height
- Earth berms with strongly non-flat surfaces: up to 5 dBA compared with a smooth trapezoidal berm at a distance 1-50 m
Two conference proceeding papers on “The efficiency of berms against traffic noise – Hosanna project” and “Acoustical performance of innovative vegetated barriers” have been presented at InterNoise 2013 in Innsbruck.


WP3

Progress towards objectives and significant results

Objectives
Make an inventory of acoustical effects of trees, shrubs and bushes based on literature review, as well as on measurements and numerical modelling. Species are identified with interesting acoustical properties for different types of applications (roadside trees, street canyon set up, forest, etc.)

Associated tasks and deliverables
Task 3.1. Inventory of scattering, diffraction and absorption by different species of trees, shrubs and bushes (TSB), including measurement campaigns and numerical modelling. Literature will be studied as a starting point, and complementary measurements will be performed. For the latter, a measurement methodology will be developed. It will be investigated how the effect of TSB can be incorporated in typical outdoor sound propagation models.
Deliverable 3.1. Technical Report on acoustical characterisation of TSB species.
Deliverable 3.5. Technical Report on acoustical effects of hedges.

Progress and Results
This is a supportive task aiming at providing basic information for other technical work packages. Most work has been performed in the first period of the project.

Measurements: In addition, measurements near hedges (in-situ) have been performed, both with dedicated in-situ methodology (a parametric loudspeaker array) and drive-by tests. This work has been performed by many different partners in the consortium, and finally summarized within WP3 in a separate added report (D3.5).
Although the noise shielding is very limited – it is the first time that it is quantitatively assessed – the more there are often wrong expectations, which could be linked to psycho-acoustical effects. An important achievement is to come to conclusions based on results that at first sight appear rather divergent.

Modelling: Simplified modelling approaches seem to correspond well with the parametric loudspeaker array test. In rare cases, high transmission loss is predicted (for very dense hedges), beyond expectations. Further analysis is needed whether this can be achieved in drive-by tests as well.
Leafs on porous substrates (like e.g. outdoor soil) remarkably change the absorption properties. Typically, at low frequencies, absorption enhancement is observed, while at high frequencies a decreased absorption is obtained. The increase at low frequencies could be relevant for road traffic noise applications. Such behaviour could be modelled with high accuracy with the FDTD method. In this way, the damped vibration modelling is validated for a second time (first in case of pressure differences measured over a single leaf, and now for leaf-porous substrate system).

Publications: The research conducted in this task has lead to publications in the proceedings of Euronoise 2012 (“Insertion loss estimate for a hedge and a greened noise barrier”, “Noise shielding by tree belts of finite length and depth along roads”) and Internoise 2012 (“Efficient approach to evaluate multiple scattering by foliage in a 3D-FDTD model”). A paper on leaf-substrate interaction has been accepted for publication in the Journal of the Acoustical Society of America (“Sound absorption of porous substrates covered by foliage: experimental results and numerical predictions”). A journal paper, to be submitted to Applied Acoustics, on the hedge measurements is in preparation.

Objectives
Investigate and optimize effects of planting schemes and exploit array periodicity to increase effects when possible

Associated tasks and deliverables
Task 3.2. Investigate and optimize planting schemes for traffic noise attenuation in typical traffic situations, including sonic crystals. This research includes scale model studies and numerical simulations.
Deliverable 3.2. Technical Report on periodic planting schemes including practical aspects.

Progress and Results
The previous research on this topic allowed to simplify tree belt calculations, namely considering sound propagation in two orthogonal planes: one to predict scattering and shielding by stems, and another one for the sound-soil interaction. This can be considered as an important break-through, and allowed calculating in a much faster way many configurations (> 100 cases have been calculated, that are combinations of stem diameter, spacing, grid orderings, belt widths, etc.). In addition, estimating the effect of finite length tree belts became possible, increasing realism of the simulations. The many simulations performed showed that a good choice of planting scheme could make a difference of more than 3.5 dBA (at a biomass filling fraction of 1.5 %). Also at lower filling fractions, a good choice of planting scheme makes sense and should be considered.

Publications: The research conducted in this task has lead to a publication in the proceedings of Euronoise 2012 (“Noise shielding by tree belts of finite length and depth along roads”). The paper “road traffic noise reduction by vegetation belts of limited depth” has been published in the Journal of Sound and Vibration (Vol. 331, p. 2404-2425, 2012).

Objectives
Investigate and optimize the effects of trees in modifying the ambient meteorological conditions

Associated tasks and deliverables
Task 3.3. Investigate and optimize effects of TSB on micrometeorology: wind, temperature, and humidity effects. This task will be performed mainly by numerical modelling.
Deliverable 3.3. Technical Report on designing optimal refraction using vegetation and trees.

Progress and Results
It has been found that the effect of relative humidity (RH) differs strongly from its effect without vegetation. Maximum “attenuation” is now found at higher RH, likely because of the heavier leaves containing water, increasing their scattering potential.

A forest strip was shown to have a positive effect in reducing nightly ground based temperature inversion effects. This comes at a slightly worse shielding during daytime by limiting the temperature decrease with height. Overall, this is estimated to be an additional benefit of a belt of trees.

Most effort has been put in limiting wind effect near shadow zones by using the canopy of trees as windbreak. A previously validated CFD-FDTD-PE model has been used for this assessment. Near berms, the use of trees was shown to yield no benefits. For a single noise wall, canopy design is useful. Strong improvements under wind conditions are possible at short distance when the bottom of the canopy touches the barrier top. This comes however at the cost of having a worse situation at longer distance downwind. When a gap is left, a global optimized improvement in downwind shielding is obtained, and negative effects by placing a row of trees are not expected. For double noise barriers, strong improvement by trees at short distance is expected, and negative effects at larger distances.

Analysis of reducing refraction in case of different noise reducing devices (single vs double noise barrier, berms) and the effect at longer distances downwind (potentially negative) are two important aspects that have not been reported before the results of this project.

A conference proceeding paper has been accepted and will be presented on ICA 2013 (Montreal), entitled: “Designing canopies to improve downwind shielding at various barrier configurations at short and long distance”.

Objectives
Optimize scattering properties of tree crowns

Associated tasks and deliverables
Task 3.4. Optimize scattering properties of tree crowns (including artificial trees) and scattering by forests. This task will be performed mainly by numerical simulations.
Deliverable 3.4. Technical Report on designing optimal refraction using vegetation and trees.

Progress and Results
Focus was on optimizing an “upward” refracting barrier-like device, by gradually increasing material density. The concept was shown to be successful. Different modelling approaches, like multiple-scattering theory, boundary element and finite-element modelling have been applied. Optimisation by genetic algorithms has been looked at to further increase shielding. A potential advantage of a porous barrier, namely decreasing wind effects, could not be confirmed.
The main goal was analysing such a completely new type of noise reducing device, and developing the necessary tools. It was shown that this idea is sufficiently strong to further work upon.
This research lead to two conference proceedings papers, one on Euronoise (“Artificial refraction of sound propagating outdoors by a sonic crystal noise barrier with increasing cylinder diameter over height”) and one on Internoise (“Numerical comparison of traditional noise screens and refractive graded index sonic crystal noise barriers in downwind sound propagation”), and to a journal publication (“Upward refraction of sound propagating outdoors by a graded index sonic crystal noise barrier”).


WP4

Progress towards objectives and significant results

Objective
To deliver models of the acoustical properties of ground surfaces for use in WP2, WP3, WP5, WP6

Associated tasks and deliverables
T4.1: Review and recommend models for the acoustical properties of ground for WP2 (barriers), WP3 (vegetation), WP5 (streets) , WP6 (combinations)
D4.1: Technical Report on applicable ground models [M6]

Progress and Results
Fifteen potential ground surface impedance models have been reviewed. Based on using no more than two parameters for infinitely thick ground or three if a ground is better modelled as a hard-backed layer, and comparisons of resulting predictions with short range propagation data from 29 grasslands, 13 forest floors, 4 gravel and sand surfaces, 1 porous asphalt and 1 railway ballast, models and parameters have been proposed for various ground types in D4.1 (delivered in M6). An extended version of this review has been published in J. Acoust. Soc. Am. and another paper on models for acoustical properties of green roof materials has been published in proceedings of Forum Acusticum Aalborg 2011.

Objective
To derive models for the acoustical effects (transmission loss) of ground treatments viz.: roughening (e.g. through cultivation or by surface patterns), introducing porous materials (for example porous concrete in sleepers and slab track for railways, areas of stones/sand), stone barriers, ground cover (vegetation, crops), buried resonators, i.e. resonating absorbers in the ground and in road surfaces

Associated tasks and deliverables
T4.2: Calculate effects of 2D & 3D roughness including grooves and bumps, acoustically-soft strips /patches, e.g. of grass or porous concrete, in hard ground.
D4.2 Technical Report on rough and mixed impedance surfaces [M12]
T4.3: Laboratory measurements on parallel wall systems, effects of added absorption, diffusion such as by quadratic residue profiles and height variation e.g. fractal surfaces
D4.3: Technical Report on the acoustical performance of parallel wall systems [M24]
T4.4: Predict effects of porous surfaces around road traffic and rail tracks using (2D) Boundary Element Method
D 4.5: Technical Report on predicted effects of porous surfaces [M37]
T4.5: Develop efficient methods for computing acoustical effects of cultivation, vegetation and crops: including multiple scattering model to allow for mixed shapes of scatterers
D4.4: Model for effects of vegetation, crops and shrubs [M24]
T4.6: Develop and evaluate resonating absorbers for embedding in ground and road surfaces.
D4.6: Technical Report on deployment of resonant absorbers in ground and road surface [M37]
4.7: Predict influence of meteorological effects on the acoustical performance of ground treatments using BIE-FFP and hybrid PE for representative meteorological conditions
D4.7: Technical report on combined effects of ground treatment, topography and meteorology.

Progress and Results
Semi-analytical predictions, numerical predictions and laboratory measurements have shown that deliberate introduction of 2D or 3D roughness on otherwise smooth hard boundaries can contribute usefully to reduction of noise from surface transport.
Roughness that protrudes above ground datum has been predicted to be slightly more effective than the equivalent recessed (i.e. below ground datum) arrangement.
Laboratory experiments have shown similar results for 3D and 2D roughness. Although the magnitude of reduction achievable by regular 2D roughness can be greater than with equivalent 3D roughness, regular 3D roughness effects are more or less independent of azimuthal angle.
Similar results have been obtained when comparing 2D impedance strips with equivalent 3D patches. Overall, laboratory experiments have shown surface impedance variation to be less effective than the deliberate introduction of roughness on hard surfaces for transport noise reduction.
D4.2 was delivered in M12 and the final version approved in M14. A paper “Diffraction-assisted rough ground effect” has beenpublished in J. Acoust. Soc. Am. A paper “Surface waves over periodic rectangular strips” is accepted for publication in J. Acoust. Soc. Am. Another “Roughness-based surface transport noise reduction” is in preparation.

Numerical predictions have shown that a series of wall clusters each of which has a fractal height pattern (maximum height 0.3 m) and with an overall width of at least 16 m can give up to 2.5 dBA additional reduction compared with a regularly spaced array of uniform parallel low walls with the same overall width.
Calculations for a 2-lane urban road and a 1.5 m high receiver indicate that a 0.3 m high lattice (a 3D roughness with inner square cell dimension of 0.2 m) arrangement is more efficient than the same width of low parallel walls and gives on the order of 4 dB reduction from 1.5 m width and 10 dB from a 12 m wide arrangement.
D4.3 was delivered in M24 but does not include subsequent work on lattice roughness arrangements which has been reported in D4.7.

BEM has been found to be more accurate than semi-analytical (Fresnel zone) methods for situations involving more than one impedance discontinuity.
Calculations suggest that replacing acoustically hard ground by a particular (low compaction) kind of soft ground starting 2.5 m from the edge of a 2-lane urban road and continuing to 50 m from the surface transport corridor can result in a reduction of about 9 dB at a 1.5 m high receiver and 3 dB at a 4 m high receiver.
Predictions indicate that there is little noise reduction advantage in dividing the soft ground into strips or patches compared with a single soft ground area.
D4.5 was delivered in M36.

It has been found that an empirical model which has been derived from published data is more accurate and useful, for example when fitting data for propagation over crops, than an equivalent porous layer model based on scattering calculations.
Calculations based on published data for a similar geometry indicate that cultivation results in less than 1 dB reduction alongside a 2-lane urban road.
However adding sufficiently dense 1 m high crops is predicted to result in an additional reduction (compared with the introduction of soft or cultivated ground) can result in a further 5 dB reduction at a 1.5 m high receiver and a further 2.5 dB reduction at a 4 m high receiver, at 50 m range.
D4.4 was delivered in M24.

A model to predict the insertion loss of an array of resonators has been developed and validated against laboratory measurements (CTH). The insertion loss of a roadside field of resonators has been calculated.
Calculations to determine the absorption coefficient of combinations of porous media and resonators have been carried out (MBBM). A field measurement campaign has demonstrated that a porous asphalt road surface including buried resonators gives approx. 3 dB advantage compared with the same porous asphalt without resonators and that this advantage is maintained over several years. The cost-benefit-ratio of resonators in porous asphalt has been optimized by exploiting alternative solutions for the laying process. The optimal number of resonators (per area) was calculated to gain a better cost-benefit ratio (MBBM).
D4.6 was delivered in M41.
Work for Task 4.7 has included predictions of rough berm effects, 2D FDTD predictions including turbulence and refraction, 3D PSTD calculations and 2D PE calculations of propagation over an impedance equivalent to a lattice surface and including refraction and turbulence.
D4.7 was delivered in M42.


WP5

Progress towards objectives and significant results

Objective
To identify parameters that are important for the acoustic properties of vegetation in urban settings, and to develop theoretical models and/or empirical formulae for predicting their acoustic performance

Associated tasks and deliverables
5.1: Identify parameters that are important for the acoustic properties of vegetation, especially for urban settings (using a series of statistical analysis). Use the results from WP3, experimental data, to derive simplified theoretical models and/or empirical formulae for predicting acoustic performance of vegetation for the cases of WP5, based on simplified leaf and vegetation structure.
D5.1: Theoretical models and/or empirical formulae for predicting acoustic performance of vegetation relating to application in an urban context (USFD, M12)

Progress and Results
While in the first stage, by considering different kinds of vegetation, effects of various parameters (water content, soil depth, vegetation coverage, etc.) on the sound absorption, scattering and transmission of vegetation and their combination with soil have been systematically examined, in terms of empirical formulae, at then, theoretical models have been explored to study the effects of controllable parameters on the sound properties. This includes soil, other growing medium, and vegetation coverage. Very good agreements have been obtained between theoretical prediction and measurements, in terms of impedance and absorption. At this reporting stage, the theoretical work has been extended to consider diffuse field conditions, and compared with measured results, so that the models can have a wider range of use.
A report, Report 5.1 was submitted in M12. Recently, some further papers on the measurement results and comparison between measurements and theoretical results have been published. A paper is being prepared for Internoise 2013.

Objective
To examine and quantify the effectiveness of vegetation combined with recycled porous materials.
To study and quantify the effects of weather elements including moisture on the acoustic performance of the recycled materials when used alone and in combination with natural granular media and vegetation

Associated tasks and deliverables
5.2: Experimentally and theoretically examine and quantify the effectiveness of vegetation combined with recycled porous materials (where the vegetation grows, on facades, roofs or ground) for acoustic benefits in urban streets, squares, as well as in road-side courtyards, also considering effects of weather on material, e.g. humidity.
D5.2 Acoustic tools for predicting combined effects of vegetation and back layers using recycled materials (UNIBRAD, M18)

Progress and Results
While in previous stage, systematic measurements were made between 4 partners, in Sheffield, to determine the impedance of various substrates (soil, water binder and recycled material) including those from recycled materials (green roof, Bradford recycled material etc), at then, theoretical predictions have been made by Open University and Bradford University, and good agreements have been obtained. This provides useful information, not only for WP5, but also to other WPs, including WPs 2, 3, 4, 6. In the mean time, more impedance tube tests have been made, systematically examining the effects of vegetation combined with growing medium. At this reporting stage, models have been expanded to consider random-incidence conditions, compared with reverberation chamber measurement results.
A report, Report 5.2 was submitted in M18, and some further papers on the measurement results and comparison between measurements and theoretical results have been published. In a paper at conference ICSV 2013 the results are also mentioned.

Objective
To examine and quantify the acoustic effectiveness of vegetation in urban streets and squares, by developing and carrying out computer simulation

Associated tasks and deliverables
5.3: Examine and quantify the acoustic effectiveness of vegetation in urban streets and squares, considering the effects of absorption, diffusion and transmission, by developing and carrying out computer simulation (radiosity/ray-tracing at USFD, FDTD at IBBT considering balconies, ESM at CTH). (Involves
developing algorithms integrating vegetation as well as subsequent coding.) .The database based on the measurements and the models/empirical formulae will be integrated into the simulation. A parametric study will be undertaken, which will demonstrate, examine and quantify the effectiveness of vegetation in noise reduction, as well as the effectiveness of strategic design and arrangements of vegetation within different street/square dimensions and configurations. A systematic simulation will be made considering a large number of configurations. The determination and design of the configurations will be based on the consideration of various aspects (urban ventilation, lighting, thermal, wind etc) and input from various expertise fields will be combined.
D 5.3: Acoustic simulation tools for urban streets/squares integrating vegetation (USFD, M24).

Progress and Results
In stage one a combined ray-tracing and radiosity (CRR) model has been developed and modified at USFD, to consider the effects of vegetation in urban context such as street canyons and urban squares, and by using the basic data obtained in Task 5.1 the effects of vegetation were demonstrated initially. Then, USFD, IBBT, CTH and CSTB determined some standard configurations to compare the results of different models, for low and high frequencies respectively. USFD used the CRR model, and IBBT and CTH used wave based models. With a series of configurations the effects of vegetation have been demonstrated systematically in urban context. In the configurations, the requirements from other non-acoustic aspects will also be taken into account. In USFD, a number of actual situations have also been considered, in addition to the generic configurations above. In the mean time, the situation in high density cities has also been considered through a series of on-site measurements and simulation. At this reporting stage, the effeteness of vegetation has been further examined in two aspects: in four actual urban squares, for which a journal paper is in preparation; and for high density apartment building group situation, for which some formulae have been derived for predicting SPL and RT, and a journal paper has been published and another one is in preparation.
A new part of work has been done by Hanyang University, Korea (HYU). Corresponding to the generic configurations in the above computer simulation, a physical scale model has been constructed and the effects of vegetation have been examined systematically. At this reporting stage, comparison has been made between Korea measurement and computation by the EU teams and good agreements have been achieved.
A number of journal and conference papers on the simulation and modelling results have been published, by each research team individually, and jointly.

Objective
To study and quantify the effects of green roof, including the role in diffraction, and also examine the acoustic effectiveness of vegetation in road-side courtyards, by developing and carrying out computer simulation

Associated tasks and deliverables
5.4: Examine the acoustic effectiveness of vegetation in road-side courtyards, considering the effects of diffraction (through green roof), absorption and diffusion, by developing and carrying out computer simulation.
D 5.4: Acoustic simulation tools for road-side courtyards integrating vegetation (CTH, M24)

Progress and Results
In the first stage, some initial simulations were made by IBBT and CTH, demonstrating the effects of vegetation on noise reduction of courtyard situation and the effects of roof including green roofs, and using some standard configurations agreed by CSTB, CTH, IBBT, USFD, and other partners, comparisons were made with different situations. Then, a series of more configurations have been considered and the results were included in Report 5.4. Recently, an actual measurement has been made, considering situations with and without green roof, to determine the insertion loss caused by green roof. There is generally an agreement between measurement and prediction. In the measurement, the basic data of the green roof have also been measured, mainly impedance. At this reporting stage, the measured results are examined in more detailed and integrated into WP6.

At Hangyang University, Korea, measurements have also been made corresponding to the generic configurations in the above computer simulations. At this reporting stage, comparison has been made between Korea measurement and computation by the EU teams and good agreements have been achieved.
Several papers on the simulation results have been published.


WP6

Progress towards objectives and significant results

Objective
Full-scale measurement campaigns for different configurations. Use acoustical measurements and psycho-perceptual evaluations in order to evaluate, in full-scale, the selected noise mitigations coming from WP2-WP5, and combined in WP6 in different situations: a city park, an urban place (city square), a street canyon.

Selection of test case location (milestone M6.1 M12).
Measurements, recordings and questionnaires in initial configurations. (Milestone M6.2 M18)
In-situ implementation of solutions (milestone M6.3 M24).
Measurements, recordings and questionnaires in final configurations, and analysis

Associated tasks and deliverables
Task 6.1: Case studies and data collection
D6.1: Technical report for task 6.1 (M38)

Progress and Results
In Lyon, Quai Fulchiron, an experimental low barrier was designed (WP2), built and extensively measured. Binaural recordings and questionnaires were made for the purpose of perceptual evaluation in WP6.3. The results of this campaign were analysed and used in WP6.2 for validation purposes. The efficiency of the low barrier was approx. 4 dBA in terms of LAeq and 6 dBA in terms of LAmax. Simulations in WP6.2 show that optimal design of the barrier it might have been possible to higher results, i.e. up to ΔLAmax = 8 dBA.
As it turned out to not be possible to repeat the Lyon experimental setup at other locations, for other mitigations, smaller test cases were sought in order to demonstrate the efficiency of mitigation on existing or ongoing projects.
In and near Berlin, measurements were carried out at 3 sites, selected in order to characterize 5 different road surfaces. The Zossen site was selected to characterize the reference road surface as defined used in the NMPB-2008 and Harmonoise methods. On the motorway, both porous asphalt and an experimental road surface incorporating resonators (WP4) were measured. At the Gneissenaustrasse site, two different low noise surfaces were measured under urban traffic conditions. At all sites, both CPX and SPB measurements as well as binaural recordings were made. This data is exploited in WP6.2 for validation purposes. Compared to the reference road surface, noise reductions of 3 dBA up to 9 dBA were observed.
In Grenoble, measurements were made near a tramway line in order to evaluate the effects of soft ground on the radiation of wheel/track contact noise. It was found that laying tracks in grass reduces noise by 3 dBA compared to tracks embedded in asphalt. Audio recordings were made for analysis in WP6.3.
In Wolfratshausen, a hedge separating a private garden from the nearby road has been removed and replaced by a vegetated barrier. Measurements were made before and after removal the hedge and after installing the green wall. The effect of the hedge was found to be approximately 1 dBA; the effect of the wall, more than 10 dBA at ground level. The results for the hedge were substantiated by a smaller measurement campaign in Grenoble, which showed an effect of 1 dBA or less.
A vegetated barrier installed to protect a private property near Cannes from motorway noise was measured, showing an efficiency of 10–13 dBA compared to the initial situation.
Monitoring of long-term noise levels took place in Belgium before and after installing a large earth mound nearby a motorway with dense traffic. Binaural recording were made in parallel for future exploitation in laboratory listening experiments. The measurements show a noise reduction of approx. 10 dB(A) closely behind the mound but only a few dB(A) further away, mostly due to the finite length of the mound.
In Eindhoven, measurements were made before and after installing vegetated roofs on a new building block. As expected, a noise reduction of 2 to 3 dBA could be estimated for receivers inside the enclosed courtyard. Impedance measurements have been made in order to characterise the physical properties of the green roof, i.e. for simulation purposes.
A template layout of report D6.1 has been produced by CSTB and sent to all partners involved in WP6.1. Responsibilities for filling in the chapters of the report have been assigned.
Contributions for partners have been collected and integrated into a draft report that has been circulated for review.

Objective
To create a new global prediction tool applicable to the abatement methods developed in the other technical work packages (WP2-WP5) and to evaluate their combined effects, both numerically and perceptual (through auralization). To make available simplified models that can be used in engineering noise mapping software. Perform parametric studies on isolated and combined solutions.
Development or adaptation of an innovative global prediction tool allowing evaluation of complex 3D configurations with combined solutions.
Exchanges with technical WPs (WP2-WP5) about what data is needed and in what format (milestones M2.2 M3.2 M4.2 and M5.2 at M18).
Validation of the tool comparing with tests of task 6.1.
Parametric study.
Auralization of combined solutions (M36)

Associated tasks and deliverables
Task 6.2: Holistic design and combined solutions
D6.2: Technical report for task 6.2 (M42)

Progress and Results
At the technical meeting in Stockholm (M6), it was decided to use the OASIS software developed by CSTB as the basis for the holistic prediction tool. This software implements both physical evaluations (static and dynamic noise maps) and auralizations. The latest versions of the NMP-2008 standard and the Harmonoise emission and propagation models have been integrated in the tool.
Standard prediction methods have limited accuracy when it comes to innovative mitigations (e.g. low barriers or special ground treatments are simply ignored in the ISO 9613-2 standard). Through so-called extensions, the software tool allows for combinations of standard prediction (engineering) methods and more elaborate numerical calculation schemes (BEM, PE, FDTD...). The extensions make use of pre-calculated numerical results on predefined source/receiver grids and interpolation in order to estimate the effects of the innovative mitigation along different propagation paths in a complex environment. The extension technique has been validated using numerical results provided by WP2, 3 and 4 as well as data from the Lyon Quai Fulchiron case study.
Digital models have been built for the Lyon Quai Fulchiron and Berlin Gneisenaustrasse sites. The OASIS software has been used to predict the effect of combined solutions (i.e. low barriers and low noise road surfaces) in urban conditions.
The QUIESST project has reused the HOSANNA extension approach to evaluate the overall efficiency of optimised barriers. For the purpose of this evaluation, a set of fictive but representative built-up sites has been created. On each site, noise levels are calculated for a large number of receiver positions, both at ground level and in front of the building façades. The CNOSSOS-EU methodology is used to link receivers to numbers of exposed populations. At the PSC meeting M30, it was decided that the HOSANNA project might reuse the QUIESST methodology and data sets in order to link mitigations proposed by the technical WP to CBA analysis in WP7. The tool has been adapted in order to take into account alternative and combined solutions as proposed by the HOSANNA project and to provide output data sets suitable for CBA. Each technical WP has been invited to produce tabular results for one or more mitigations in one or more representative sites. This data has been processed and converted to noise mapping data handled over to WP7 for further analysis.
Through auralization, the innovative mitigations proposed by the technical WP are linked to perceptual evaluations in WP6.3. The auralization technique developed by CSTB has been adapted, fine-tuned and validated, based on experimental data from the Lyon and Berlin test cases. Special attention has been paid to calibration of the simulated audio sequences with respect to the available experimental evidence. Post-processing tools have been developed in order to simulate the different measurement methods and to produce numerical results directly comparable to the data.
The auralization handles rolling and propulsion noise separately and the data from the Berlin test case has been integrated in order to simulate the effect of low and ultra-low road surfaces. For the Lyon and Gneisenaustrasse cases, combined solutions based on low barriers and low noise surfaces have been simulated. The combined solutions allow for noise reductions up to 10 dBA, LAmax.
Simulated audio sequences for individual, optimised and combined solutions have been made available for perceptual evaluation in WP6.3.
A template layout of report D6.2 has been produced by CSTB. Responsibilities for filling in the chapters of the report have been assigned. Parts from contributing authors have been collected and integrated into a draft report and sent around for review.

Objective
To validate designs of innovative mitigations from the technical work packages (WP2 – WP5) through field trials, including visitor questionnaires for perceptual evaluation and panel groups in the field, as well as laboratory listening tests using auralization.
Carry out questionnaire study in real life cases and in in-situ evaluation places of task 6.1 in order to validate new indicators.
Choose binaural signals from the recordings in the in-situ configurations and create (i.e. auralize) binaural signals for the same cases.
Laboratory listening tests using the chosen and the auralized binaural signals
Develop psychophysical models of the relationship between spectral and time-pattern properties of urban soundscape and perceptual outcomes, including perceived annoyance and tranquillity.
Develop new acoustic indicators for parks and green areas that capture psychological restoration and aesthetic experience
Apply knowledge of perceptual and stress responses to urban sounds to evaluate and optimize innovative acoustic design methods, separately and in combination.

Associated tasks and deliverables
Task 6.3: Perceptual evaluation
D6.3: Technical report for task 6.3 (M42)

Progress and Results
Listening experiments have been conducted using binaural recordings from Lyon, Quai Fulchiron. The results complement results obtained in the questionnaire study.
Further analyses of questionnaire data from Lyon, Quai Fulchiron was conducted with focus on correlation between acoustic measurements and various advanced as well as simplified soundscape quality indicators. Work has been conducted on applying advanced models for sound source identification (Notice-event-model) to predict questionnaire responses collected in the Quai Fulchiron-study. Unfortunately, these analyses did not prove fruitful, because the Quai Fulchiron case was dominated by road-traffic noise - also after treatment- leaving little room for variation in perception of other noise sources.
Listening experiment was conducted on binaural recordings of tram noise from Grenoble (recordings with hard and soft ground). Data analyses have been completed and result have been summarised.
Binaural recordings with and without barrier and hedge at Wolfratshausen were evaluated. It was found that presence of bird song and low-frequency noise at some but not other recordings made the recordings not suitable for listening experiments. It was not possible to find recording segments of sufficient length undisturbed by irrelevant sounds
Auralized signals of road-traffic noise at Lyon, Quai Fulchiron, simulating effects of noise barrier and road surface, have been produced. Preliminary tests suggested that the auralized sounds were not realistic enough for a true validation experiment, where real and auralized sounds are evaluated for perceived realism. However, the sounds may be used for annoyance experiment, and such an experiment was planned to be conducted. Unfortunately, the time between the delivery of signals and the time window for running experiment before the listening room at SU was renovated turned out to be too short. Therefore, it has not been possible to conducted the experiment within the project time.
Audio-visual experiment has been conducted by HUY, evaluating joint visual and auditory effects of noise barriers and of street vegetation.
SU and HUY in cooperation conducted listening walks in Stockholm focusing on visual and auditory aspects of urban environment, in particular perceived tranquillity. The results provided insight into the relative weight of auditory and visual aspects of urban environments, and also provided psychoacoustic relationships in line with previous results on soundscapes in urban opens spaces.


WP7

Progress towards objectives and significant results

Objective
To provide a cost-benefit framework for assessing the costs and benefits of the noise mitigation methods developed as part of the project taking into account the additional benefits of implementing several measures at a time. Benefits from increased greenery and material changes, with respect to CO2, thermal
insulation, and local air pollution, will be included. To integrate the costs and benefits of the specific measures, developed in the project, within a broader
CBA framework, where silent surfaces, traffic calming, façade insulation and other measures are already captured (5th Framework SILVIA, 6th Framework SILENCE). The framework supports prioritisation, and proper “dosage” of measures. Monte Carlo simulation and sensitivity analyses provide insights into the robustness of the CBA results.
To supplement the CBA analysis with qualitative assessments, for benefits to which it is difficult to assign monetary value (recreational, aesthetic, and appreciational aspects).
To assess the various institutional settings in which noise mitigation projects become anchored, with different stakeholder groups in the study areas, and assess how financial and organisational support for the projects can be secured.

Associated tasks and deliverables
Task 7.1: Establishment of an overall framework for the cost-benefit analysis based on previous field tested CBA-framework – a spreadsheet model developed by us under the 5th Framework project SILVIA on low noise surfaces.
Task 7.2: Establishment of templates (Web-based) for each substantial WP/partner to input initial unit costs and benefits of the separate measures. Updates to the values can be posted through the Internet as field and implementation results become available. (Input from). Additional input from on recreational and appreciational values.
Task 7.3: Application of the CBA framework and unit costs to the mitigation measures implemented in the study areas. The framework will be sensitive to national differences in accounting principles and in local unit costs. Where applicable, reduced costs stemming from the reuse of waste material will be taken into account. Supplementary measures, where unit costs and benefits are available, will be handled within the framework.

Progress and Results
The CBA framework has been established. Completed: Deliverable 7.1:
Technical report on "Web‐based templates for input/updating of costs and benefits of proposed measures"

Completed: Deliverable 7.2:
Calculation framework with updated values.
Completed: Deliverable 7.5: Qualitative supplemental assessment of non-monetised aspects/area value.
The web-tool has been upgraded to Expression Engine version 2.0 as envisioned.
Monte Carlo simulations are now fully integrated with the Cost-Benefit Analyses. Statistical, measurement, and assessment errors are now incorporated into the framework.

The tool has been applied to Green roofs and green walls/vegetative facades. A facility for running different alternatives and compare them in one and the same run has been implemented, allowing the direct comparison of competing alternatives.
The results from D7.5 on green roofs and walls have been incorporated in the CBA tool and the Cost Benefit Analyses. The results show that including non-acoustic benefits can have a decisive effect on the Benefit cost ratios of green measures. This is a potentially important result. The valuations are tentative, and need further elaboration.
Completed: Deliverable 7.4: Extended CBA analyses of measures (single and packaged) for the field studies.
Completed: Deliverable 7.3: Technical report of legislative, financial and organisational settings in study areas.

Potential Impact:
Summary of dissemination and impact

To summarize the dissemination work of WP8, the web-site has been constructed and is running according to plan (www.greener-cities.eu); for the Handbook we have a contract with a publisher; the Summary Brochure has been printed; and the workshops have been held.

In addition, the technical reports of the project will be made publically available via the project website.

Furthermore, during the time of the project, 25 peer review journal papers have been produced as well as about 50 conference papers. Further peer review journal papers are planned, but not yet submitted for publication. Also recent and upcoming conferences will have papers presented as result of the project, e.g. Internoise in Innsbruck, September 2013, where more than five papers are planned, and Transport Research Arena, in April 2014, where one abstract from the project consortium has been accepted and a manuscript has been submitted.

The details of the progress of WP8 is shown below. Thereafter follows a description of the work with the Handbook and with the Summary Brochure. The Handbook is not yet completed, but the overall structure and several chapters have been produced and we have a contract for publication of the book with the publisher Spoon Press (Taylor & Francis Group). A first complete draft of the Handbook is planned for October 2013. The Summary Brochure was printed in January 2013, and was presented at the workshops in Lyon, London and Munich. The workshop in Stockholm was conducted in December 2012, before the brochure had been printed. Therefore, a leaflet presenting the outline of the brochure was produced for the Stockholm workshop.

In addition to the above-described dissemination, there is indication on wider societal impact. From the inputs at the workshops it is evident that many representatives of cities and other planning bodies are highly interested in the noise abatement methods that are suggested by the HOSANNA project. Also, projects on national levels have been initiated as well as funding applications made for in-situ implementation projects and further product developments.


Progress of dissemination workpackage (WP8)

Objectives, tasks and results

Objective
To disseminate the scientific findings of the project to the various target groups of end-users (policymakers in EC and member states, NGOs, decision makers at regional and municipality level). Specifically: see 8.1-3 below See below Task 8.1 – 8.6.
Associated tasks and deliverables & Progress and Results: See below Task 8.1 – 8.6.

Objective
8.1. To maintain a website with information about the Project, latest news, document databases, etc (updated at least 3 times per year).
Associated tasks and deliverables:
Task 8.1. Maintaining a website with information about the project.
- Setting up the website including secure file sharing structure within consortium and layout
- Compiling basic information and initial content to be available on the website
- Update the web-site, at least 3 times a year and make available the Handbook in an easily readable format

Progress and Results: Task 8.1: Web-site is constructed and running according to plan (www.greener-cities.eu).

Objective
8.2. To produce a Handbook and Summary Brochure for holistic and sustainable abatement of noise by optimized combinations of natural and artificial means. The Handbook contains around 10 chapters, each with 10-20 pages on innovative noise mitigation including examples, intended for practical uses, such as architects, landscape architects, city planners, noise control engineers, and decision makers (see further description below). The book will be published and printed. A summary brochure in the form of a 20-25 page report will be electronically available and printed. Task 8.2: Production of the
Handbook and the Summary Brochure.
- Define structure and style of Handbook.

- Generate template for input from other workpackages.

- Write main text for chapters on technical methods, based on results.

- Write main text for chapter 10. The contents on cost-benefit analysis of abatement, and the role of legislative, financial and organizational settings for successful abatement.

- Compile chapter texts and finalize publication of Handbook and Summary brochure.

Progress and Results: Task 8.2: The Handbook will be published by Taylor & Francis (Spoon). An agreement between the publisher and the Editors (SU, TOI and Sthlm) has been signed. Contributor agreements (one per chapter in the handbook) will be signed later on.

Structure and style of handbook has been defined. A general template for input from other work packages has been created and sent out to the first authors of the chapters.

According to revised time plan, first drafts of chapters should be delivered to Editors M42 (April 2013). Most chapters were delivered by M42. The remaining chapters include description of work conducted up to the very end of the project, which explains the need of time beyond M42. Taylor & Francis is informed and expect to have drafts ready by beginning of autumn (October 2013).

The Summary brochure has been produced. The Brochure was printed in January 2013, and was presented at the workshops in Munich, Lyon and London. For the Stockholm workshop, December 2012, a leaflet was produce that described the content of the upcoming Brochure.
The work with the Summary Brochure and the Handbook has been described in the Technical report for task 8.2.

Objective
8.3. To organize workshops disseminating the Handbook to end-users in Stockholm, Lyon, London and Germany (Berlin, Dresden or Munich).

Associated tasks and deliverables: Task 8.3.
Workshop, presenting Handbook to end-users in Stockholm.
Workshop, presenting Handbook to end-users in Germany
Workshop, presenting Handbook to end-users in Lyon.
Workshop, presenting Handbook to end-users in London.

Progress and Results: Task 8.3.
The four workshops were conduced as planned:
Stockholm workshop Dec 10, 2012
Lyon workshop, Jan 22, 2013
London workshop, Jan 28, 2013
Munich workshop, Jan 30, 2013
The workshops have been described in the deliverables for tasks 8.4 - 8.7.


Deviation and corrective action

Task 8.1. To maintain a website with information about the Project, latest news, document databases, etc. (updated at least 3 times per year). No deviation.

Task 8.2. To produce a Handbook and Summary Brochure for holistic and sustainable abatement of noise by optimized combinations of natural and artificial means. The Handbook contains around 10 chapters, each with 10-20 pages on innovative noise mitigation including examples, intended for practical uses, such as architects, landscape architects, city planners, noise control engineers, and decision makers. The book will be published and printed. A summary brochure in the form of a 20-25 page report will be electronically available and printed.
Deviations: The Summary Brochure was slightly delayed. It was planned to be printed in time for the first workshop in Stockholm. It was printed in time for the second workshop in Lyon. Corrective action: A 4-page leaflet describing the content of the project was produced and distributed at the Stockholm workshop. Impact: None, since brochure was made available to all participants at the Stockholm workshop. They were informed how to download the Brochure or how to order a printed version (no charge).

Task 8.3. To organize workshops disseminating the Handbook to end-users in Stockholm, Lyon, London and Germany (Berlin, Dresden or Munich). No deviation.


Details about the Handbook

The Handbook will be published by Spoon Press (part of the Taylor & Francis Group). An agreement between the publisher and the Editors (SU, TOI and Sthlm) has been signed. Contributor agreements, one per chapter in the handbook, will be signed later on.
Structure and style of handbook has been defined. A general template for input from other work packages has been created and sent out to the first authors of each chapter. At this stage, complete drafts exist of chapters 2, 3, 4, 5, 6, 7 and 10.
Figure 4 shows the preliminary Handbook cover. Title: Environmental Methods for Transport Noise reduction. This is a draft of the blurb (for the cover):
“Transport noise is an increasingly sensitive issue and new legislative and regulatory pressures are driving its reduction. Hitherto relatively overlooked intelligent and sustainable solutions include the use of green areas, green surfaces and other natural elements in combination with artificial elements in urban and rural environments for reducing the noise impact of road and rail traffic. Ground and road surface treatments; trees, forests and tall vegetation; greening of buildings and other surfaces; and innovative barriers can contribute to powerful cost effective noise abatement whether the noise impact is assessed in terms of sound levels (including spectra and time patterns) or perceived environment (including annoyance and soundscape quality).
This handbook presents evidence-based guidance on novel noise abatement methods, outlines noise prediction methods which can be integrated with noise mapping software, details assessment methods for perceived noise and highlights the economic benefits, including positive effects on urban air quality and CO2 levels. It is derived from the outputs of HOSANNA, a major EU research project.”

Below is a list of each chapter with outlines.

1. General principles of noise reduction
J. Forssén, et al.
Noise from surface transportation is a great and increasing environmental problem. New methods are needed for reducing noise at the source and along the propagation path from source to receiver. The chapter starts with an acoustic characterization of road traffic and railway noise, and briefly reviews possible reduction mechanisms at the source. Noise reduction along the propagation path is then reviewed in detail, first describing acoustic principles behind conventional noise reduction, such as screening and absorption, and then describing the main principles behind the new methods described in the following chapters of the book.

2. Natural and recycled materials
K. Horoshenkov et al.
This chapter describes acoustic properties of natural soils, gravels and man-made recycled materials. The authors discuss the key pore and frame characteristics that control the acoustical properties of these materials and describe methods to manufacture acoustically absorbing materials from recycled waste. The authors then discuss the effect of environmental factors on the acoustical properties of these media, including moisture content, pore material inhomogeneity, contamination and compaction. Finally, the results of measurements and predictions of acoustic properties of a variety of material specimens and their combinations are presented and discussed in terms of their noise reduction potential.

3. Innovative barriers
J. Defrance, et al.
The authors review the main models predicting sound propagation in the presence of noise barriers along railways and roads. The best models are then applied to assess the acoustic performance of barrier systems exploiting natural and recycled materials, such as vegetated low-height obstacles, gabion barriers, and combinations of classical barriers, shaped soil, and vegetation. Simulations are carried out for a large range of typical road, railway and tramway configurations in rural and urban environments. Finally, the authors present global results for different positions of receivers in terms of extra noise abatement of innovative barriers compared to conventional solutions.

4. Trees, shrubs and bushes
T. Van Renterghem, et al.
The basic interactions between sound waves and vegetation elements are described and the distinction is made between direct and indirect effects. The importance of such interactions are assessed, and measurement methodologies and measurement results are shown. A tree belt is an interesting solution to achieve road traffic noise reduction. Noise shielding is obtained as a combination of multiple scattering by mainly the tree trunk layer (direct effect) and the presence of a forest floor (indirect effect). This practical case is worked out in detail in a second section, and guidelines are provided to optimise noise shielding by (mainly) non-deep tree belts. The range of expected effects are predicted as well. The possibility to improve wind fields near noise reducing devices like noise walls and earth berms under downwind conditions is discussed. This is a clear example of an indirect effect that can be exploited to decrease noise levels. A number of design guidelines were identified.

5. Noise Reduction using Surface Roughness
K. Attenborough, et al.
Sound reflected from the ground either cancels or reinforces sound travelling directly between source and receiver depending on frequency, the source and receiver locations and the acoustical properties of the ground surface. At the cancellation frequencies, there is attenuation in excess of that due simply to wavefront spreading or atmospheric absorption. For sources at heights below 0.3 m and receiver locations between 1.5 m and 4 m height at distances of between 10 m and 50 m from the road, tramway or railway above hard and smooth ground the cancellations are at relatively high frequencies and do not affect the overall noise. However, by inserting sufficient roughness with heights of up to 0.3 m, the cancellation is modified to be in a frequency range that will reduce noise from surface transport sources. When the roughness is composed from regularly-spaced features, the cancellation is diffraction–assisted and results in more than one narrow-band attenuation maxima. This may be useful for narrow-band sources but does not necessarily result in greater attenuation of broadband sound than over randomly-spaced roughness. Incorporation of height variation and clustering of roughness elements can lead to higher attenuation than over the same overall width of roughness composed of the same number of elements of uniform height. Lattice configurations are more effective than parallel walls since they offer a higher insertion loss per unit width and a smaller change in attenuation with the azimuthal angle between moving source and receiver. Roughness in the form of parallel grooves or recessed lattices also gives rise to extra attenuation but about 3 dB less than that achievable with protruding roughness elements of the same height and extent. Surface roughness is able also to improve the acoustical performance of an otherwise relatively smooth and hard berm. The acoustical performance associated with roughness is improved if the elements are slightly absorbing. Under acoustically-neutral meteorological circumstances, the roughness-induced attenuation persists as the receiver moves further away which is not the case with a conventional fence-type noise barrier. However, as is the case with a conventional barrier, the attenuation due to roughness is reduced under downwind and temperature inversion conditions. The relevant phenomena, data, predictions and physical concepts are detailed and the results presented are intended to encourage exploitation of these effects for noise reduction along transport corridors.

6. Porous ground, crops and buried resonators
K. Attenborough, et al.
Transport noise travelling near to naturally-occurring porous ground surfaces, such as grassland, can be reduced at frequencies relevant to noise control as the result of interference between direct and ground reflected sound, i.e. the ground effect phenomenon introduced in the Chapter V. Although it is known that different types of naturally-occurring porous 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 (other than trees, shrubs, hedges and bushes which are considered in Chapter X), 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 non-porous 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 pre-formed resonating chambers. Resonators can also be buried in hard or porous ground to increase noise reduction. Laboratory data and predictions are presented that demonstrate the usefulness of this method.

7. Vegetation in urban streets, squares and courtyards
J. Kang, et al.
One of various ways in which growing vegetation can improve urban areas and the health and well-being of people is by changing the acoustic environment. This chapter presents findings of computer simulations to examine and quantify the effectiveness of green roof and green wall (vertical garden) systems in reducing road traffic noise for streets, squares and roadside courtyards. Noise reduction by sound absorption in reflected and diffracted (over roofs) sound paths is investigated. Particular attention is paid to the importance of vegetation placement relative to the receiver/listening positions and frequency dependence. Also, the effects of a low barrier made of green wall substrate are studied for an installation on the ground and on the top of buildings surrounding a courtyard.

8. Prediction and simulation of holistic noise reduction from combinations of solutions
D. Van Maercke, et.al.
Accurate evaluation of noise reduction methods requires valid calculation methods, based on empirical, analytical or numerical models. Such models should be able to predict the effects of holistic combinations of different noise reduction techniques and to reflect these effects when updating strategic noise maps. In combination with micro-scale traffic simulations, these methods can predict the short-term variations of noise levels from which newly proposed indicators for soundscape quality can be estimated. When combined with synthesis of source signals, such simulations can drive auralization and virtually reality, providing a direct access to perceptual evaluation of traffic noise levels and soundscape quality.

9. Perceptual effects of noise reduction
M.E. Nilsson, et al.
Many noise reduction methods change temporal and spectral properties of noise. This influences perceived annoyance, over and above the effect related to an overall reduction in sound pressure level. In addition, reduction of a dominant noise source will increase the saliency of other sources, which may influence the overall quality of the sound environment (or soundscape). This chapter reviews such perceptual phenomena and evaluates acoustic indicators aimed at predicting perceived annoyance and soundscape quality before and after noise reduction.

10. Cost-benefit analyses
R. Klæboe et al.
Funding of noise reduction competes against funding of medical services, crime prevention and other worthy causes. To promote noise reduction, it is therefore useful to demonstrate when and where its benefits outweigh its costs. The benefits of the methods described in the previous chapters include acoustic (noise reduction) and non-acoustic effects, such as reduced dust, CO2-uptake and recycling of waste material. Examples of situations are given where the abatement measures are acoustically effective, inexpensive to implement, affects a large number of people, and thereby provides high levels of benefits relative to the costs.


Summary Brochure

The Summary Brochure was printed in January 2013. The brochure, entitled ‘Novel Solutions for Quieter and Greener Cities’, is a 48 page document summarising the main findings of the project. It contains one section per handbook chapter. A number of illustrations were produced for the Brochure, several of which will also be used in the Handbook (see examples in Figure 4).

A pdf-version of the Brochure may be downloaded from the project’s web page (www.greener-cities.eu).

List of Websites:

Project website: www.greener-cities.eu

The coordinator contact is as follows.

Jens Forssén
Chalmers University of Technology (CTH)
Division of Applied Acoustics
Department of Civil and Environmental Engineering
SE-41296 Gothenburg, Sweden
Tel: [phone]
Fax : [phone]
www.ta.chalmers.se