Transportation Noise
The noise of road vehicles is mainly generated from the engine and from frictional contact between the vehicle and the ground and air. In general, road contact noise exceeds engine noise at speeds higher than 60 km/h. The sound pressure level from traffic can be predicted from the traffic flow rate, the speed of the vehicles, the proportion of heavy vehicles, and the nature of the road surface. Special problems can arise in areas where the traffic movements involve a change in engine speed and power, such as at traffic lights, hills, and intersecting roads.
Construction Noise, Public Works Noise and Military Noise
Building construction and earth works are activities that can cause considerable noise emissions. A variety of sounds is present from cranes, cement mixers, welding, hammering, boring, and other work processes. Construction equipment is often poorly silenced and maintained, and building operations are sometimes carried out without considering the environmental noise consequence. Street services such as garbage disposal and street cleaning can cause considerable disturbance if carried out at sensitive times of day.
In certain instances, military activities may be an important noise source such as noise produced by heavy vehicles (tanks), helicopters, and small and large fire arms. Noise from military airfields may present particular problems compared to civil airports, for example, if used for training interrupted landings and takeoffs (so-called touch down).
Building service noise can affect people both inside and outside the building. Ventilation and air conditioning plants and ducts, heat pumps, plumbing systems, and lifts, for example, can compromise the internal acoustic environment and upset nearby residents.
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