A noise barrier is a vertical structure along a road or railway that blocks the spread of sound to the surroundings and thereby reduces noise pollution.
How a noise barrier works
A noise barrier interrupts the direct sound wave between the source and the dwellings behind it. The sound has to bend over the barrier, which sharply reduces its strength in the “sound shadow” behind it. The higher the barrier and the closer it is to the source, the better the effect.
Key principles:
- Mass and density: the barrier must be heavy and free of gaps
- Height: determines the size of the sound shadow
- Absorption: an absorbing front face prevents reflection
There are two main forms:
| Type | Feature |
|---|---|
| Noise wall | Vertical wall of concrete, wood, glass or metal |
| Noise embankment | Earthen bank, often planted, requiring much space |
Application
Noise barriers and embankments are placed along motorways, railways and busy urban roads. Applications:
- Protecting residential areas from road traffic
- Shielding rail noise near stations
- Combining with quieter asphalt or façade sound insulation
Transparent barriers of glass or plastic are used where views and daylight matter. An earthen embankment suits a green setting but requires more space.
Related terms
- Noise embankment
- Noise pollution
- Sound insulation
- Decibel
- Sound absorption
- Infrastructure
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