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NOISE BARRIERS AND ASTHETICS

Noise barriers can be designed in one of two ways, to blend into the environment, or to make a dominant visual statement. Both can work well in different situations. A barrier can be blended into an area by using light and transparent materials. This allows natural light to pass through, and in many cases reduces the perceived height of the barrier. In other situations a well designed barrier with strength of form and a firm, distinctive silhouette may help to strengthen the area. Noise barriers are often "unsightly" and so take away from the acoustical effects of the barrier.

As noise barriers are often viewed at speed, their appearance needs to be simple, because small decorations are likely to blur and appear cluttered when viewed at speed. However, it must also be taken into account that local residents will also have to view these barriers everyday, often for extended periods of time. Excessive detailing of the barrier can increase the dominance of the barrier. It is generally more desirable to use colour, texture and landscaping in the overall design to help the barrier reflect the character of its surroundings.

Noise barriers are often built using repetition of a single design for continuity and to keep costs down. Such barriers can become boring and bland and can therefore diminish the landscape quality. However too much variance in design can have the same affect.

The colour of noise barriers is an important aesthetic element. Generally colours are either chosen to help the barrier blend in to the environment, or to create a pleasing visual effect. Plantings at the base of noise barriers can improve the aesthetics of the barrier, as well as giving it a more natural feel. Planting is a great way to hide a barrier. Trees and shrubs can be planted at the base of barriers or vines can be grown on the barriers themselves. Plants which are already found in the area can be chosen to help the barrier blend in.

The materials a barrier is made of should be visually sympathetic to the character of the surrounding landscape. Wood, metal, concrete and transparent materials are all possible. Transparent barriers are often chosen to allow light through. On some roads it may be desirable for motorists to have views out of the freeway. However this can sometimes conflict with the desires of residents who do not want views into the freeway. Frosting, colouring and silkscreening techniques can all be used to obscure vision through the transparent barriers, while still allowing light to pass through.

The sheer size of some noise barriers can have an adverse visual effect. Constructing tall barriers next to small houses and buildings can dwarf residents, and can have a damaging affect on the character of the area. It could also create large shadows and change local air movement, affecting the microclimate.

The angle of noise barriers also affects their aesthetics. A barrier with a vertical profile can make people feel confined. Angling the wall can reduce this effect. However deciding which way to angle the wall can also be difficult. Angling it away from the road gives drivers an increased feeling of space, but may make an increased feeling of confinement for those on the other side and visa-versa.

Noise barriers often appear incongruous or characterless, this is often a result of poor design related to cost reduction. Although their main function should be to control traffic noise, the visual effect should not damage the surrounding areas. As said by Benz Kotzen and Colin English in their book Environmental Noise Barriers (1999), "…costs should be properly balanced against environmental and visual impacts, and the potential effects on the quality of life. It must be remembered that barriers will be part of the landscape for a long period of time. It is important that these structures and the materials they comprise stand the test of time and they will not do this if the visual quality of the barrier is sacrificed for cost-cutting reasons." (page 92)


Some of the visual and aesthetic benefits and desadvantages of a number of different styles of noise barriers are below.


Earth Mounds:

Benefits:

  • Natural appearance

  • May not appear to be a noise barrier at all

  • More likely to give an open feeling, unlike screens

  • Can often be integrated into the local landscape, particularly through planting

Disadvantages:

  • Take up a lot of space

  • Often appear ugly and unnatural, particularly when plants have not yet developed

  • May require regular maintenance, ie. watering, weeding and re-planting

  • Natural looking barriers can, in certain areas, look out of place

Timber Barriers:

Benefits:

  • Often resemble garden fences, allowing them to fit easily into suburban landscapes

Disadvantages:

  • The rustic appearance of timber barriers can appear out of place in some urban settings, especially is a lot of construction materials such as concrete and steel are used in the area

  • Using timber barriers over a long stretch of road can becoming visually boring, as there is normally not much variation in design

Sheet-metal Barriers:

Benefits:

  • Normally weather well, and if properly designed can maintain their attractiveness over a long period

Disadvantages:

  • If not well designed can be extremely bland

Concrete Barriers:

Benefits:

  • Can be visually affective as long as they are not left as flat concrete surfaces

  • Colours can be used to improve their appearance

Disadvantages:

  • Generally ugly and visually unaccommodating unless well designed

  • If left flat, can become a target for graffiti vandalism

Transparent Barriers:

Benefits:

  • Are neutral and less visually intrusive, so they are less likely to affect the character of an area

  • Allow light through, keeping natural light conditions the same

  • Do not create a visual obstruction, allowing access to views, and reducing the sense of being trapped

Disadvantages:

  • Generally require cleaning

  • Sometimes have shorter life spans than other materials

  • Small amounts of damage, such as scratches and cracks, are easily noticeable

  • Privacy for residents living next to the freeway can sometimes be an issue

Cantilevered Barriers:

Benefits:

  • Reduce barrier height by locating the top of the barrier closer to the noise source

  • Creates a more open feeling for people on the outside of the barrier

Disadvantages:

  • Can create an unpleasant shadow on the road side of the barrier as a result of the sun being blocked by the cantilevered part

Vegetation:

Benefits:

  • Vegetation alongside roads is much more environmentally friendly and aesthetically pleasing then other conventional barriers

  • Can be very acoustically effective as long as planting is dense and deep

Disadvantages:

  • Takes up a lot of space on what can sometimes be valuable land

  • Can take a long time until vegetation is established