Noise Pollution and Social Acceptance of UAM

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Autonomous systems are transforming business and the economy, and their impact on the future will grow with increased integration into our daily lives. Recent advancements in urban air mobility (UAM) – autonomous systems that transport cargo and passengers at low altitudes in urban and suburban areas – are moving us toward a safer and more efficient transportation future. However, the momentum of this evolving industry also brings challenges posed by increased urban noise.

AUVSI recently hosted an XPONENTIAL 2021 preview webinar on Noise Pollution and Social Acceptance to discuss how the UAM industry can analyze and mitigate noise challenges. Michael McNair, Vice President of Aerospace, SAE Industry Technologies Consortia, spoke about urban noise ecosystem concerns that will impact acceptance of UAM. Onur Bilgen, Assistant Professor, Rutgers University, addressed UAM technology concerns by sharing information about his team’s work on a low-noise propulsion system.
 

Noise perception is contextually dependent. 

As Michael McNair explained, public perception of sound goes far beyond a simple decibel measurement. Urban sounds range from accepted ambient sounds, to workable understood sounds, to unwanted extraneous sounds – but the way people perceive and categorize sounds along this range is not fixed. Because perception of noise is impacted by culture, emotion, and stimuli from other senses, perception of sound varies as these factors change over time and between places. Adding to this complexity is the challenge of identifying shifting values – sounds that are considered tolerable in today’s urban landscapes may not be tomorrow and sounds that are not tolerated today may be an expected part of daily life in the cities of the future. 
 

Noise management solutions vary by need.

With noise already a part of urban landscapes, the UAM industry must distinguish between acceptable noises and those that must be limited, and then determine a workable way to do so.
 

The first option is to reduce noise at the source by altering the number of rotors, rotor design, or rotor speed. Large UAM systems like air taxis involve complex rotors that produce more structure-born sound than smaller drone systems. Current commercial market solutions that control vibration or pitch do not always sufficiently reduce sound for operations in certain areas and come with technological disadvantages.
 

Dr. Bilgen explained how his team at Rutgers is working to reduce the level of sound emitted from rotors using piezocomposite blades. Piezoelectric materials change shape when electricity is applied, thereby offering solutions for thrust vectoring, acoustic sound, and vibration control. Systems that incorporate this technology could see increased bandwidth, more compact packaging, reduced fabrication and maintenance costs, increased functionality, and even reduced power consumption.
 

The second option is to abate noise in unwanted areas by managing UAM routes, arrival and departure times, and aircraft distancing. While conventional commercial flight is already restricted by noise abatement operations in place at airports, UAM brings its own challenges with increased air density, lower flight altitudes, and flight paths that are closer to people and buildings. FAA is working to identify UAM needs and is expected to update flight standards in the coming years.
 

The third option is to accommodate the local community’s expectations and tolerance level. UAM operations could be restricted by curfews, limits on the types of operations allowed, or quotas that decrease the total number of aircraft in operation.
 

Finally, noise can be reduced in specific regions through land use planning. Urban areas can zone airspace as high-density regions near multimodal transit hubs or noise-sensitive regions away from these services.
 

The UAM industry must collaborate toward assured autonomy. 

With so many noise management options to choose from, it is clear that solutions will vary between urban areas depending on noise perception and overall acceptance of UAM systems. As UAM technology advances, so must discussions on the future of UAM integration in our daily lives and within a multimodal transit system. By collaborating toward consensus-driven standards, industry stakeholders can adopt a holistic approach that addresses noise concerns and ushers UAM toward a future of assured autonomy.
 

XPONENTIAL 2021 offers attendees an opportunity to hear more about this topic from thought leaders, technology experts, and policymakers. Register now for the event’s virtual educational programming in May to continue this discussion on noise pollution and social acceptance.