By Denise Soesilo and Bo Jia
We began our journey in 2015 helping organisations and health actors plan out and implement medical drone operations in rural settings. However, as technology has advanced, we see more exciting projects that bring drone deliveries into urban areas. One example is the planned Rigi Tech operations across Lake Geneva in Switzerland, proposing daily deliveries of medical samples between doctors offices in Rive Gauche and Coppet across the lake. The hope is to cut health care system costs, reduce emissions and remove cars off the streets, which everyone agrees is great. But this also brings drones closer to where people live and work every day and raises questions with regard to new types of noise pollution.
Urban Air Mobility (UAM) is defined by EASA as an air transportation system in and around urban environments providing connectivity within the cities and among regions. In recent years, Europe has been perceived as a market leader in the development of UAM. According to EASA, the European UAM market size is predicted to be 4.2 billion EUR by 2030 (see the report we wrote together with the European Institute of Innovation and Technology for more details).
According to an EASA study on social acceptance of drones, noise is the second main concern after safety. The study concluded that people often find drone noise more annoying than other city sounds. To develop sustainable UAM in Europe, it’s thus critical to address the noise-related concerns expressed by EU citizens. We found that technical and policy guidance is slowly emerging but many unknowns still need to be solved.
From a technical perspective, there are ways to make a drone quieter, such as using noise-reducing propellers and noise-reduction shrouds. The industry is working full steam on these approaches and whilst critical, there are also important social elements that need to be addressed. In the following we discuss what we have learned about how to effectively address people’s concerns through public engagement.
The core of this approach is twofold. When engaging with communities we have learned that transparency and early engagement are key. In addition, technical elements and available information needs to be compiled and shared in a way that helps communities engage in a meaningful way. This also signals that industry players are applying best practices to address any potential issues.
The first step is to ground discussions on facts and data as much as possible and to provide transparency. This means actual drone noise data needs to be collected and modeled or measured in situ. This data will be crucial to inform the affected neighbourhood as well as report to local authorities. This data will be complemented with ancillary information such as prevailing regulations and noise pollution benchmarks. The second step is to enagage the community and understand their perception and fears. Often the history of the community plays a strong role in beliefs and perceptions about noise and industrial projects. If a community has previously had poor experience with environmental nuisance, then this will likely also come to the fore during these discussions.
Measurement of Drone Noise
The measurement aspects are an evolving topic, and there are still gaps in academia and practice. Although different projects and research teams have tried to measure the noise, there is currently little industry standard or binding regulation in this domain.
In a real-life measurement, the steps of different approaches include noise metrics selection, test environment conditions, drone spatial positioning, microphone characteristics, and mathematical modelling. It is a technical activity that requires specialised equipment and scientific methodology. Currently, the most relevant guideline is the EASA draft guideline published in 2022 on noise level measurements for drones below 600kg. This guideline is intended to be used on a voluntary basis and does not constitute applicable requirements for the certification of drones, but it also points to the direction for potential future regulation in Europe. It provides noise measurement standards in the specific category that includes activities such as package deliveries, powerline inspections, wildlife control, mapping services, aerial surveillance or roof inspections. The guideline detailed the entire procedure of noise measurement, including test environments, spatial positioning, speed measurement, test equipment, microphone setup, and gives detailed technical requirements for each step.
Another way to obtain noise models is through noise simulation, which requires less hardware and testing. A team from Hong Kong has measured the noise impact of delivery drones in an urban community based on a flight simulation and noise assessment platform, which contains the flight dynamics, noise source prediction and long-distance propagation modules. The EU-funded project AURORA is in the process of validating a noise pollution model. The APIS project from Stockholm also aims to establish a user-friendly platform which allows for the simulation of noise from drones.
As mentioned above, many studies have pointed out that drone noise is perceived as substantially more annoying than road traffic or aircraft noise due to special acoustic characteristics. The noise of drones does not resemble the noise of contemporary aircraft which leads to an important uncertainty in the prediction of the perception of drone noise. Different metrics such as Tonality and Loudness-Sharpness interaction might need to be measured to be able to account for the perceptual features of drone noise.
Recommendations
After obtaining noise data and understanding people’s perceptions, what can we do to address concerns? The key is when and how to engage affected communities. First of all, it’s always better to start outreach as early as possible. It can be in the form of a community meeting or roadshow that invites affected people. For the drone project team, it’s suggested to designate a person or even a dedicated unit, depending on the size of the project, to be in charge of community affairs and sensitization. This team should be introduced in brochures or on the website of the project with a detailed description of what they do. A fixed and familiar face can help win trust from the affected people.
As for the content of the communication, the accurate measurement of the drone noise should be shown to the audience. This can be a noise mapping in the neighbourhood or a printed noise report that can be handed out to the participants to form a basis of discussion along with the efforts the project is already taking to address concerns.
Besides the noise data, it’s always helpful to communicate the purpose of the drone operation. incliding any added value to the neighbourhood as well as to society that will be derived from the operation. People will more likely accept an inconvenience if it is for a positive societal cause such as the delivery of medical supplies or reducing traffic and pollution.
About the authors
Bo Jia
Bo has supported several digital agriculture projects, covering topics such as M&E, digital finance, e-commerce, drones, etc. His research helped push for more programmatic and strategic approaches to analyse digital products and investments in the organisation. He is also experienced in ecosystem mapping to identify potential investment opportunities and improve resource mobilisation.
Denise Soesilo
Denise is an expert in unmanned aerial system (UAS) use in humanitarian and development settings. She has worked with donor agencies and development organizations, humanitarian and United Nations organisations, advising on the application and implementation of drone technologies. Denise served as the director of flight in the African Drone Forum - Lake Kivu Flying Competitions and implemented numerous other drone operations. Through her work, Denise has enabled the safe operations of nearly a dozen cargo drone companies. In addition, Denise has led the implementation of the European Union Humanitarian Aid innovation grant on drones in humanitarian action. Denise has authored several publications on UAS in development and humanitarian action.