Kenichi Teramachi

On a Simplified Calculation Method of Equivalent Sound Level of Road Traffic Noise Which Consider the Difference Between the Pavements

In the new environmental standard for road traffic noise, equivalent sound level was adopted instead of medium value. At the same time, the prediction model of road traffic noise was proposed by Acoustical Soc. of Japan. This model is utilized for the environmental assessment, and the application range is also wide. However, designers can not calculate easily the value of the road traffic noise using this model. Therefore, authors proposed the calculation method which satisfied two following requirements regardless of usual pavement, drainage pavement, though the application range is limited to the roadside noise as the automobile steadily runs.(1) Equivalent sound level can be easily calculated using mathematical expressions and figures.(2) Designers can easily decide noise reduction countermeasure of the object site.

IMPROVEMENT OF RATE FOR MEETING ENVIRONMENTAL QUALITY STANDARDS OF ROAD TRAFFIC NOISE BY SMALL LOW-NOISE CARS AND DRAINAGE PAVEMENT

都市部においては自動車の騒音に係わる環境基準の達成率が依然低い状態にある。それゆえ本研究では、道路からの距離や高さによらず有効な音源の段階での対策を施した場合に、減音量がどの程度見込まれ、達成率の向上がどの程度はかれるのかについて、北九州市内の主要道路を対象に検討した。なおここでは、実現性が高いと思われる2種類の対策、排水性舗装の施工と電気自動車等の低騒音車 (小型) の導入を取り上げた。その結果、通常より骨材粒径が小さい5-10mmで排水性舗装を施工し、小型の低騒音車を導入すると、環境基準達成率は昼間で28から87%、夜間で32から69%、両時間帯で24から67%と著しく向上することが認められた。