Highway Noise and Acoustical Buffer Zones

Highway noise generation could be reduced at the source, but shielding by various types of barriers and protection of the exposed population by adequate zoning can also reduce its impact. The adequacy of solid barriers to attenuate noise is well established. However, the use of vegetative barriers by themselves or in combination with solid barriers may often be advantageous. Vegetation is known to be more effective in reducing noise of high frequency. Characteristics of vegetative barriers which affect noise attenuation are: density, pattern, height, species, undergrowth, ground condition, and location in relation to noise source and receiver. Atmospheric parameters which influence noise propagation are: wind and temperature gradients, wind direction, wind speed, temperature, and humidity. Optimal width of buffer zones depends on source characteristics, e.g., speed, type, propagation path conditions, and land use characteristics.