RIVM is publishing four new studies in the context of the Programme-Based Approach to Measuring Aircraft Noise (PAMV). Two of these studies look at the quality of measurements and models. For high noise levels, these correspond quite well. For lower noise levels, the difference between the results of measurements and modelling is more pronounced. RIVM therefore recommends conducting more research into lower noise levels. Another recommendation is to structurally check the quality of models using measurements. Doing so could increase citizens’ trust in the models used. The other two studies are about how annoyance is experienced. RIVM recommends continuing research into the effect of peak noise levels on annoyance together with citizens.
Research into measurements and models
It is crucial that the results of measurements and modelling of aircraft noise are consistent and correspond with each other. This is not always the case. That is why a consortium of RIVM, NLR and the consultancy To70 has compared the results of measurements and modelling of aircraft noise around Schiphol.
The results of measuring and modelling correspond quite well for higher noise levels
For high noise levels, the results of measurements and modelling correspond quite well. For lower noise levels, the difference between the results of measurements and modelling is more pronounced. This is in part due to lack of good monitoring data. Measuring points do not always register flights with lower noise levels. This applies in particular to measuring points at greater distance from flight paths. One of the reasons for this is background noise. It can be hard to differentiate aircraft noise from other sources of noise, such as road traffic. This is a problem if we want to find out whether the models are also reliable for low noise levels. According to the World Health Organization (WHO), low noise levels can already have an impact on health.
Research into annoyance and peak noise levels
The rules for aircraft noise in the Netherlands are based on models of annually averaged values. People who live near Schiphol question whether these annually averaged values for aircraft noise are in line with their experience of severe annoyance and sleep disturbance. According to them, peak levels of aircraft noise should be taken into account more. RIVM investigated whether models using indicators that take peak noise levels into account would better reflect the annoyance experienced by residents. Together with residents, RIVM also carried out local measurements and looked at how this annoyance is experienced.
Indicators
Adding additional indicators makes modelling annually averaged values more complicated. While the outcomes better match the experience of local residents, this is only to a very slight degree. RIVM therefore recommends not making the modelling more complex and instead conducting more research into how annoyance is experienced together with local residents. An approach such as citizen science could be used for this, for example.
Citizen science and annoyance research
Last summer, together with a small group of residents living in the vicinity of Schiphol, RIVM investigated how peak noise levels and the number of flights flying overhead affect annoyance. The participants installed sound level meters at their own homes and could use an app to keep track of the extent to which they experienced annoyance. The research shows that, in addition to the noise itself, the number of aircraft flying overhead also affects annoyance. Moreover, people who are sensitive to noise react more strongly to this than others.
This is the first time research into aircraft noise annoyance was carried out in this way. The results of this exploratory study show that this is an effective research method, for example for people who are sensitive to noise. Carrying out more such research would thus be worthwhile.
Recommendations
The publication of these reports concludes phase 2 of the PAMV programme. RIVM recommends that the Dutch Ministry of Infrastructure and Water Management should continue to structurally validate models of aircraft noise. Additionally, more measurement data are necessary to do this for low noise levels as well. Finally, it is important to carry out research into annoyance with local residents on a regular basis.