7. Quiet urban areas: measuring (2) 10,1 49,8 45,9 54,7 Zuiderpark 7,2 50,0 46,8 54,1 Wijkpark Oude Westen 3,7 57,9 55,0 58,5 Sidelingepark dB dB(A) dB(A) dB(A) L A10 -L A90 L A50 L A95 L day
12. Quiet urban areas: assessment (3) Evaluation Overall Visual Acoustic environment Duration of stay Age Quote Wijkpark Oude Westen 7.1 Neutral Neutral 1 hour 37 “ Baken van rust in hectische bouwput.” Sidelingepark 6.9 Good/ neutral Neutral 0,5 hour 57 “ Groen, want rustig is het niet. Het is wel lekker, maar je komt er niet voor het geluid” Zuiderpark 7.8 Good Good/neutral 2 hour 43 “ Een mix van besef van de stad en toch even buiten zijn. Echt buiten”
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Hinweis der Redaktion
Legislative and policy context for the initiative are formed by the European Environmental Noise Directive, requiring authorities to delineate quiet areas within and outside agglomerations in order to protect areas where the acoustic quality is good or relatively good. Regarding nature areas this EU requisite has been practice in the Netherlands since decades, but urban areas have been more or less neglected. Rotterdam defined actions and policy goals regarding noise in its noise action plan based on three pillars, that are tackling hot spots by applying low noise road surfaces on about 50 km of municipal roads during the next 4 to 5 years, preventing new hot spots through sound spatial planning and defining actions regarding protection and improving quiet urban areas. The approach was supported by the results from the biannual survey on environment and quality of life in 2009, in which citizens stated 75%: quiet around dwelling is (very) important 65%: quiet in neighbourhood is (very) important 16%: visits a (quiet) park daily The new appointed elderman on environment underlined the need to address noise and health issues, by setting policy goals regarding noise and green urban areas. The pilot study on three urban areas fed into this policy programme.
Three parks have been selected in order to assess the developed approach for analysing soundscape of urban parks. The Sidelingepark is a relatively small park of 2 ha in a residential area, which is highly impacted by noise from a highway at approximately 50 meter distance. The park is green with many trees and smaller bushes, and some spots with benches where residents frequently rest. Wijk park Oude Westen is a small green area of 1 ha in the city centre of Rotterdam, including a primary school and a private garden of the residents living in 3 stock buildings surrounding the park. The park is rectangular and its main entrance is from a busy road combined with a tramway. Zuiderpark is a large park of 225 ha with various functions and varying vegetation. The park is mainly used for sporting, cycling and walking and has large grass fields, sporting areas and biking routes.
The annual survey on quality of life topics in Rotterdam incorporated questions on noise annoyance, in accordance with ISO standards, and on urban parks. Data from this survey however has not yet been assessed and cross analysed with data from the field survey, and will thus not further be addressed in this presentation.
During 3 weeks noise levels and noise spectra have been measured at one selected spot in the three parks. Although the EU Environmental Noise Directive uses Lden as noise indicator, soundscape research proved that other indicators are needed in describing sounds as perceived by humans. Therefore we decided to assess the sounds, or rather noise levels, using additional acoustic indicators, such as Lday, LA95, LA50 and the difference between LA10 and LA90. LA95 and LA90 are known as descriptors for background noise or the most prominent noise levels. LA50 has been used in soundscape research as an indicator corresponding well with the perception of the acoustic quality by humans.. LA10-LA90 is a good descriptor of the variance in noise levels; a large difference between both levels means a high variance in sound levels.
In Sidelingepark relatively high overall noise levels are found, as well as a limited variance in noise levels. The proximity of the highway, with constant traffic flows, is explanatory for these findings. Wijkpark Oude Westen and Zuiderpark have similar levels for Lday, LA95 and LA50, but the variance differs significantly. The higher value in the Zuiderpark might be the effect of the infrequent event-like sounds from the metroline passing near the park above ground level.
In spring this year in total 150 visitors of the three parks have been surveyed on the perception of the visual and acoustical aspects of the respective parks. A questionnaire has been developed, based upon an earlier version as used in studies in Turin and Paris. The questionnaire contained open and closed questions on sounds heard, the perception of these sounds and on sound sources.
In assessing the field survey data we applied the categorisation of sounds as proposed by Berglund, Nilsson and Axelsson, that is nature sounds, human sounds and mechanical sounds. The latter category in this sheet has been futher divided in the subcategories traffic sounds, air conditioning and other mechanical sounds. The presented results underline the preliminary conclusions on the measured noise levels and expert characterisation of the urban parks, for example when we look at the high scores at nature sounds in the Zuiderpark and on traffic sounds in the Sidelingepark.
The assessment of the urban parks revealed some interesting results. The Sidelingepark having the highest overall noise levels and lowest score on overall evaluation of the park, scores highest on the evaluation of the acoustic environment as well as the pleasantness of the sounds present and heard in the park. Further research is needed to define the explanatory factor, that even might be a non-acoustic factor such as visual quality, the fit of the park with the specific use of the park for example in the availability of sufficient, well kept walking lanes and benches.
The importance of other factors, in addition to soundscape or purely acoustic factors, is further supported by the high overall evaluation of the Zuiderpark and of the visual quality despite a lower score on the evaluation of the acoustic environment. Worthwile mentioning in this line is the relatively positive evaluation of the Sidelingepark regarding visual aspects, that might be counterbalancing the high noise levels measured. Another explanatory factor might be the expectations of the park’s users and the reason for visiting the park. A relative high percentage of visitors interviewed stated they passed the park on their way to or from home and to walk the dog.
Based upon the data collected and assessed for the three parks in Rotterdam the following conclusions regarding the acoustic quality can be drawn. LA50 seems to be a good indicator for the perception of the acoustic quality of the urban park. Although a larger database of parks in Rotterdam and in due time other specific areas in larger European cities is needed, some noise levels expressed in Lday and LA50 are proposed as preliminary trigger values for subsequent actions in Rotterdam. LA50 seems to correspond well with holistic description of sounds Applicable in comparative studies, no absolute sound levels derived
The pilot in Rotterdam has been evaluated on several topics regarding the methodology and the instruments used. The aim is to further improve and in due time standardise the tools for soundscape research at municipal level targeted at urban parks. Regarding the questionnaire used the overall conclusion is that it seems to provide sufficient, relevant data for characterising the visitors’ perception of the soundscape and other values of the area. A rather strong disadvantage is the processing time and the knowledge of statistical and social processing techniques that is sparsely available at local administrations. Standardisation as worked on by a newly established ISO sub working group might support this development in future. In addition, the evaluation learned that the order of issues addressed in the questionnaire, might need changing. In the follow-up research we suggest to start assessing the perception of the acoustic environment through questions on description of the sounds heard based upon the perception quality protocol from the Swedish research. Then the interviewee will be asked to recall the sound sources heard, the sounds and sound sources that annoy him, and the sound sources that are perceived as pleasant. The second part of the questionnaire will assess overall environmental quality including visual aspects. As such we assume that visual input will be less dominant in the assessment of the soundscape. A cross analysis of both sequences of questioning is planned for next year.
In order to improve both visual as well as auditive qualities green barriers are suggested for the Wijkpark Oude Westen, enclosing the small park at the northern part close to the road. The
In order to improve both visual as well as auditive qualities green barriers are suggested for the Wijkpark Oude Westen, enclosing the small park at the northern part close to the road. The
