Noise abatement measures

A buffer zone is an area left between a noise source, such as a busy road and buildings. The busier the road, the wider the buffer zone needed to provide sufficient distance between the noise source and buildings. Thus, a buffer zone is not always a possible solution in large centres where the land is needed for construction. If it is not possible to leave a distance between the noise source and buildings, noise barriers and the positioning of buildings in relation to the road can prevent the spread of noise.

Noise barriers are built to prevent road noise from spreading to living spaces, such as residential homes, schools and day-care centres. There are various kinds of noise barriers. A noise barrier can refer to, for example, an earthwork, a wall, a lowered road, a tunnel or a non-residential building. These can also be combined by, for example, building a wall on top of an earthwork. Noise fencing is a lower option used mainly in places with very limited space, such as bridges, and can also serve as safety fencing. The reflection of noise from hard, flat surfaces can be diminished by vegetation. Though vegetation does not significantly affect the sound transmission, it can reduce the perception of noise as annoying by obscuring the noise source from view.

For the noise barrier to function well, it must be well designed and correctly positioned in relation to the noise source and the area to be protected. The height and materials used must also be suitable. The disadvantages of a noise barrier are that it only protects the lower floors and is expensive to build.

A noise barrier must be high enough to sufficiently prevent the spread of noise. A high enough barrier should cover car tyres when viewed from the area to be protected from noise. The material of the barrier must be sufficiently dense to prevent the noise from penetrating it. A well-built noise barrier reduces noise by about 15 dB. However, if buildings are located close to the road, noise reduction is usually between 5 and 10 dB.

Low-noise road surfaces refer to road surfaces that cause less driving noise than standard asphalt. The disadvantages of low-noise surfaces are that they do not withstand wear as well as standard asphalt and are more expensive to build. Therefore, low-noise surfaces are practical only on roads with less than 12,000 vehicles per day and a maximum speed limit of 60 km/h.

Just like with any other surfaces, studded tyres in particular cause degradation to low-noise surfaces. Studded tyres also cause more noise than non-studded winter tyres. Furthermore, studded tyres are worse in terms of air quality, as they release particles from the road surface, which increases the amount of street dust. Thus, in terms of noise, air quality and road durability, it would make sense to give preference to non-studded tyres.

Tyre noise is the most significant source of traffic noise when driving at speeds in excess of 60 km/h. Reducing traffic speeds on major roads especially would, therefore, reduce noise. Decreasing the vehicle speed from 80 km/h to 60 km/h decreases the noise level by approximately 3.5 dB.

In old buildings, one of the most important ways of noise abatement is to improve the exterior soundproofing, meaning the exterior walls, windows and any replacement air vents. Improving the insulation of residential buildings should be considered, especially in connection with various modernisation works. Replacing windows with better insulating ones, for example, can improve the soundproofing of the building, but only provided that the walls are properly insulated. If the building’s supply air is drawn through a hole in the wall, replacing the supply air ventilator with a noise-insulating model can reduce the noise exposure. In the case of air traffic noise, the insulation of the roof must also be considered. The roof and its joints and the inlets and outlets of the air-conditioning systems on the roof can allow noise to transfer into the building.

However, such renovations require careful planning to ensure that improving the soundproofing does not impair ventilation. The Building Control Department can advise in more detail on the permit requirement of the facade renovations, for example. Replacement of windows and ventilation filters requires the permission of the housing company. A guide for voluntary noise abatement (in Finnish) is available for download below.