ANIMA intervention: Rotterdam

Besides being small, Rotterdam airport has a Regional Consultation Committee, including stakeholders and community representatives, and project teams can be formed to address specific activities. One such team was formed for the topic of this case study.

This case study investigates the evaluation of an alternative departure procedure aiming to reduce noise annoyance for as many residents as possible and involve communities around the airport in the decision-making process. The study would evaluate whether the changes in the calculated noise levels would be perceived by representatives of the community and discuss their findings among each other and the project team.

The technical analysis included a quick-scan of changes in noise exposure for the departure route for runway 06. The results of the investigation showed a 10% reduction of highly annoyed people in the 56dB(A) L_den contour, while there would be a 2% increase in the lower 40dB(A) L_den contour, and a shift from number of people annoyed from the north to the south of the route.

An online listening test presented participants with simulated audio samples of aircraft noise for the current and alternative departure procedure at five locations, each affected differently by the changed procedure. These are shown in Figure 1, together with the current (grey line) and alternative (blue line) departure procedures. Those participating would not know beforehand the locations that were evaluated or which of the two sounds that were compared was the current or the alternatively departure procedure.

^{Figure 1: Current (grey) and alternative (blue) departure procedure and the five examined locations for the listening test}

Due to COVID-19, the listening test had to be performed at participants’ home. Participants listened to the two departure procedures for each of the five locations, and after that, listened to the two procedures at the same time by alternating between them in a 4 second interval. Participants rated the sounds by 7-point Likert scale between -3 and +3(0 points if both routes were perceived equally loud). In total, 25 participants provided their subjective evaluation.

During the informational meetings afterwards, technical details related to the two departure procedures were explained, such as the noise levels calculations, technical aspects of the procedures and the listening test setup. The actual locations and which sound (the first or the last) belonged to which departure route were revealed as well. Participants were asked whether they would personally benefit from a possible change in procedure, whether they thought that the overall community would benefit and whether the community engagement strategy was helpful and valued.

Listening test scores were averaged over all 25 participants. For each of the five locations illustrated in Figure 1 (above), the listening test scores were in line with the expected LAmax noise level from the calculations. The calculated changes in noise levels for location 3 (4.3dB) and location 4 (4.4dB) were almost identical. However, the score from the listening test suggests that the higher noise level for location 3 was perceived as more annoying (score 1.8), compared to the increase in noise level for location 4 (score 1.2). It seems that for higher noise levels, a reduction is more appreciated whencompared to further reduction of a lower noise level.

Mixed results were received for questions about the personal benefit and the overall benefit for the community. Most participants put the overall benefit of the community first and reported that the process, the explanations, the listing test and the meetings were helpful and valued. However, some participants were unhappy about the approach as they felt the noise exposure and the annoyance was only shifted and not reduced.