Controlling construction noise can pose unique problems for contractors. Unlike general industry, construction activities are not always stationary and in one location. Construction activities often take place outside where they can be affected by weather, topography, atmosphere, and landscaping. Typical construction noise such as heavy earth moving equipment can move from location to location and is likely to vary considerably in intensity throughout a work day.
As a rule, administrative and engineering controls should always be the preferred method of reducing noise levels on worksites. Administrative controls are management decisions governing work activities, work rotation, and work load, in order to reduce workers’ exposure to high noise levels. Typical management decisions that reduce worker exposures to noise are: moving workers away from the noise source; restricting access to areas; rotating workers performing noisy tasks; and shutting down noisy equipment when not needed. Noise perimeter zones can be established and roped off where sound levels exceed 85 dBA in order to expose as few workers as possible. Engineering controls modify the equipment or the work area to make it quieter. Examples of engineering controls are: substituting existing equipment with quieter equipment; retro-fitting existing equipment with damping materials, mufflers, or enclosures; erecting barriers; and general maintenance. When these controls are proven unfeasible, earplugs or noise reduction earmuffs as a permanent solution should be considered.
An effective way of reducing noise is to locate noisy equipment behind acoustic barriers. These can be full or partial enclosures or portable screens depending on the equipment type and location. The best acoustic barriers combine a dense blocking material such as mass loaded vinyl, and an acoustic absorber such as fiberglass. The distance between a noise source and the receiver can be considered a barrier as well. Doubling the distance from the noise source lowers the noise level by 6 dBA.
Municipalities may have noise ordinances established to protect passersby and the surrounding community. In this instance acoustic sound curtains need to be installed around the site perimeter. Sound curtain systems are typically erected utilizing pre-fabricated barrier/absorber panels that can be attached to existing structures such as chain link fencing. To be effective, the noise source should not be visible and the barrier should be located as close as possible to either the noise source or the receiver.
Although most construction noise is generally unavoidable, it can often be controlled through improved work practices and the utilization of proper noise control products. The responsible person, who is the owner, occupier or contractor, must take all reasonable and practicable measures to minimize noise resulting from the activity and to reduce its impact on the surrounding environment, and protect exposed workers.