Noise from Roads, Expressways and Highways

The 3 main source of noise from a highway or expressway are:
1) Exhaust system of motorcycles, cars, trucks and buses
2) Engine noise generated from vehicles accelerating or ascending a slope
3) Tyres interacting with pavements

Highway noise are measured in dBA or "A" weighting which emphasize sound from between 1 kHz and 6 KHz

Studies have shown that expressways and highway noise loudness doubles as
1) Volume of vehicles increase by 10 folds
2) Travelling speed of vehicles doubles

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