According to several recent studies, noise in cities has become an increasing hazard to health. Environmental noise, that is, noise from traffic, industrial activities, or amplified music, which reaches internal spaces, is not merely an annoyance. It has been linked to cardiovascular disease, diabetes, dementia, and mental health. As the world urbanizes, more people are exposed to excessive levels of noise. How can urban design and architectural strategies help to prevent this?
According to both the World Health Organization (WHO) and the European Environment Agency, at least 20% of the population of the European Union suffers from prolonged noise exposure. In Western Europe, this results in the loss of 1.6 million 'disability adjusted life years' (DALYs), or years of good health, per year. Noise levels at night are particularly problematic as they lead to sleep disturbance, which in turn can elevate the risk of developing anxiety and depression. The WHO recommends nighttime noise levels of a maximum of 30 decibels in bedrooms for quality sleep, a level which is often exceeded in urban environments.
The sonic environment of a city can be described as the urban soundscape. This covers all sounds, including those regarded as pleasant, such as birdsong and children playing. However, cities can be dominated by other sounds that can be undesirable, particularly at night. Road traffic is the most commonplace source of noise, especially in cities where the use of the horn is excessive. Other modes of transport, such as trains and airplanes, are also sources of noise, albeit in fewer areas. High-density living can increase the prevalence of other sources of noise, such as barking dogs and loud music, and proximity to industrial activity can cause noise issues in the daytime. Construction sites are another source of noise that can be difficult to control.
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The first step in controlling noise pollution is separating noisy activities from residential areas. It is commonplace for industry and intensive leisure activities with loud music to be positioned in designated parts of the city. Similarly, airports are normally positioned at the edge of the city, although they continue to affect parts of the urban area. Less easy to control are traffic and public transport, which are required to reach residential and commercial areas. Zoning can play a part if it encourages mixed-use districts with short commute distances, encouraging travel by walking and cycling and, hence, less traffic noise. This reduction in traffic volume has the added benefit of reducing air pollution.
Traffic Planning
Road traffic produces the most noise annoyance. Taking England as an example, 100,000 DALYs were lost due to road traffic noise in 2018, compared with 13,000 from railway noise and 17,000 from air traffic noise. In addition to zoning, as noted above, road traffic noise can be reduced by physical means, such as by installing low-noise asphalt on busy roads or encouraging the use of quiet tires. Electric vehicles tend to be quieter than those with internal combustion engines. Infrastructure to promote walking, cycling, and the use of public transport can also reduce the amount of noise in road traffic.
A more holistic approach to traffic reduction is to pedestrianize whole streets. One of the most ambitious examples of this is the 'Superblock' of Barcelona, Spain. Implemented in stages since 1993, the project involved the amalgamation of city blocks into single 'superblocks' with vehicular access restricted within. As well as creating more car-free, and therefore quieter, streets, the superblock project also reduced car use overall as it encouraged walking and cycling, thus reducing both noise and air pollution.
Less drastic but also effective are the car-free days in Paris, France. Held on the first Sunday of every month, the four central districts of Paris become pedestrianized for the day, with no motorized vehicles permitted. Additionally, the city has also been reducing its speed limits. In October 2024, the ring road saw cars having to stay below 50 km/h. In addition to improving safety and reducing emissions, driving at this speed is also quieter.
Across the Atlantic, a case from 1975 highlights noise pollution from elevated railway lines. In New York, USA, teachers at a school in Manhattan noticed a marked difference in performance between students who sat on the railway side and those who sat on the quieter side. This eventually led to the transport authorities installing rubber pads on the tracks to reduce the sound vibrations emitted. Noise from steel wheels is expected on the railways. Some transit systems, like the Paris Metro, are designed with rubber tires partly to reduce noise levels.
Green Infrastructure and Sound Barriers
Parks and trees can provide buffer zones between noisy infrastructure, such as freeways, and urban neighborhoods. Woodland has the ability to reduce noise by five to ten decibels for every 30m of width. The East London Green Grid is one project with multiple goals that can contribute as a noise buffer. Alternatively, sound barriers can also be constructed close to the noise source where space is limited. Within urban streets, trees and green walls can offer sound absorption and scattering that mitigate the reverberation effect between building facades.
Quiet Urban Spaces
Dense urban centers can never be completely devoid of noise, and pockets of space that offer moments of calm can be invaluable in the city. These can be secluded gardens, sheltered courtyards, or small sculptural landscapes. An early example of such a space is Paley Park in New York. Opened in 1967, it is a pocket park with a stone floor, a grid of honey locust trees, and ivy covering the surrounding walls. Tables and chairs designed by Eero Saarinen and Harry Bertoia, respectively, are arranged between the trees. Most importantly, the rear wall has a water feature which, as well as providing a moment of joy, also creates gray noise which masks the sounds of the city.
Building Design
Finally, the design of buildings contributes to the mitigation of noise annoyance. Orientation away from sources of noise is the first step. Sound-attenuating external walls as well as acoustic double- or triple-glazed windows can protect the internal environment. The challenge is to balance ventilation requirements with acoustic ones - in some cases, mechanical ventilation becomes the only feasible solution if the environmental noise is excessive.
A Comprehensive Approach
Urban environmental noise is not mitigated by one solution alone, but a combination of several strategies. In addition to those mentioned above, technology is available for continuous monitoring of noise levels throughout the city. Public awareness can push the efficacy of these strategies further, while adequate enforcement of policy is necessary. Noise reduction and mitigation in the urban environment is no less important than other environmental health requirements, contributing to improved cardiovascular health, mental well-being, and increased healthy life years. Most noise mitigation strategies have added benefits, such as encouraging active travel methods or reducing air pollution, and generally improve the experience of our cities.
This article is part of the ArchDaily Topics: Building Wellbeing: Designing Spaces for Healing, presented in collaboration with the Hushoffice.
With its line of A-class pods Hushoffice helps create acoustically balanced workplaces that offer great environment for collaboration and focus, foster employee wellbeing, and accommodate the needs of neurodiverse staff, as well as employees with motor impairments.
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