Noise Management in City and Urban Planning

                                                                                         

Growing cities means growing noise. This is especially true in mixed-use urban environments that often contain commercial premises (entertainment, retail, office, hospitality or light manufacturing) sited close to residential uses such as apartments.

The need for local authorities to adopt sound land use planning is a growing practice.

Noise can be thought of as unwanted sound and can vary greatly in volume. Noise can cause annoyance, speech interference, affect performance and concentration, mental health and disturb sleep.

Difficulties often arise where noise-sensitive land uses (such as residential activities) move into or close to established commercial areas or major infrastructural assets such as ports or airports. This is often referred to as ‘reverse sensitivity’ for an explanation of reverse sensitivity and relevant case law).

One technique for dealing with the issue of reverse sensitivity is to ensure people are fully informed of the environment which they are proposing to move into.

Another consideration of factors planners are observing for mixed-use areas include:

* Time of day: There is less tolerance of noise by residents when it occurs at night. Therefore district plan noise limits are typically lower for night.
* Level of sound: Sound levels can range from loud (exceeding the normally occurring or existing background sound level by 10 dBA or more) through to relatively low level with bass or beat components. District plan provisions should allow for some noise to be emitted, but only up to allowable limits measured at the residential location (often around 45-55 dBA).
* Type of sound: Some sounds have a special audible character that can cause additional annoyance.
* Location of premises: Commercial and industrial areas located close to residential sites will often have more noise issues than those occupying sites well within commercial or industrial zones (further from residential sites). District plan noise provisions usually allow higher levels of noise (day and night) within commercial and industrial zones. Distance, and the placement of barriers between the source of the noise and those receiving, are mitigating factors but the ability to use these can be limited in mixed-use environments. Where residential activities locate in established commercial or industrial areas it is more practical for the new residential use to insulate itself from noise than it is for existing commercial uses to comply with acceptable residential noise levels.
* Body corporate and private undertakings: Complaints can arise where noise-sensitive residences are located in the same premises as a noise-making commercial activity. Clauses within leases or body corporate constraints covering noise nuisance often place such complaints beyond the scope of territorial authority action. However, many territorial authorities successfully deal with these matters in the same way as if the parties were located within separate buildings.

Managing noise in the city usually starts at its source. For new noise generating activities, control can be achieved by incorporating appropriate buffer distances. However, as buffer distances are often not practical in inner-city areas where differing land uses tend to be located in close proximity, measures such as the use of noise barriers or insulation may present a more realistic management method.

Barriers may include such features as:

* solid walls or fences to stop or deflect sound
* bunds
* other non-noise sensitive structures
* topography (locating activities in depressions or behind hills for example).

Barriers to control noise emission or to reduce noise received can be effective, but the effects of reflected sound need to be considered within the design and orientation of barriers. Factors such as orientation and materials used in the construction of barriers should be considered. Acoustic consultants can provide detailed guidance to match the specifics of individual sites.

Vegetation is not considered a good sound barrier as it will not block noise emissions unless plantations are very dense. Within inner-city mixed-use environments there are few opportunities to provide planting capable of mitigating noise.

Noise control is most effectively achieved on smaller sites by paying particular attention to design before constructing any buildings. The layout of premises…the location and orientation of openings, loading bays, doors, windows, and car parks…and on-site vehicle circulation patterns are all important for good noise control.

The use of noise management plans may be incorporated into a district plan through permitted activity standards associated with particular (usually known) land uses, or their formulation and compliance with them made a condition on a resource consent. Some district plans actually specify that a noise guidance plan must be prepared to comply with rules.

Other considerations within such districts include:
* Providing indoor living spaces in mixed-use areas with a reasonable standard of acoustic protection is emerging as an effective method of addressing reverse sensitivity.
* Specifying the standard required for acoustic insulation (for example the materials to be used, or the level of sound reduction to be achieved).

As the world’s population grows and cities become denser, the necessity of noise ordinances and the consideration of soundproofing residential areas is becoming a must.

About the author:
Mark Rustad is President of NetWell Noise Control, based in Minneapolis, MN. Founded in 1991, NetWell is a leading supplier of ceiling tiles, acoustic products, sound proofing treatments, and online acoustical consulting services. NetWell’s sound management skills are packaged into the industry’s premier website. For more information, please visit eSoundproof.com. Discover first hand why so much of NetWell’s business stems from the referrals and repeat orders they receive from satisfied clients around the world.

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