Road traffic noise reduction of drainage pavement with small air gaps among grains is well known. However, traffic flow over many years fills those gaps with mud and sand, thereby degrading the noise reduction effect. To regain that effect, cleansing or reconstructing the pavement is necessary after precise assessment of the air gaps. For that purpose, acoustical diagnoses of drainage pavement are proposed and test results are introduced. One method is to check sound absorption of the pavement surface, which normally has high absorption near frequencies of 1 kHz, which is related to the reduction of road traffic noise. The use of a particle velocity sensor together with a microphone greatly simplifies measurements and judgments. Another analysis method is based on sound propagation through air gaps in the pavement. Transmission characteristics clearly indicate pavement conditions. Low-attenuation sound transmissions are shown in a wide frequency range below 1 kHz for sound air gaps, and weak transmissions in a narrow frequency range are shown when air gaps are filled. These acoustic diagnostic methods are effective in investigating porous drainage pavement. © 2009 Institute of Noise Control Engineering.
It is a serious problem with the construction industry that there has been a growing shortage of skilled workers together with the problem of their aging. Rationalization of work, labor saving, and safety control through automation of construction equipments have also been desired.The automation of dam concrete transfer has been the urgent demand since its transfer requires skilled cable crane operators and the job itself is a typical repetitive work.To meet such needs, the authors formed a project team in OBAYASHI Corporation since 1989 and have been engaged in system development. The project team have accomplished the full automated concrete-transfer system being centered around the cable cranes and practically applied the systems to dam construction sites.
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