The Japanese standards ASJ RTN-Model 2008 and ASJ CN-Model 2007 - problems and trend-setting features

摘要

Due to the revision of ASJ RTN-Model 2008 and ASJ CN-Model 2007 it has been necessary to re-do the implementation of them in our sound propagation calculation program SoundPLAN. With updating the regulations we gathered some interesting experience which we would like to present here. With the road traffic noise prediction model ASJ RTN-2008, published in April 2009, the Acoustical Society of Japan (ASJ) has supplied a modern as well as practical realization in the domain of sound prediction. This applies in particular to the sound propagation calculation, which provides calculation methods for some very special demands on geometric modeling (e.g. tunnels, bridges, special noise barrier types) as well as techniques for the evaluation of complex sound propagation situations ("slit-method" in the calculation of diffractions (e.g. for reflections) and the calculation of the sound transmission through noise barriers). However the second Japanese standard ASJ CN-2007 for construction noise still has a number of problems which will be identified and analyzed. Possible solutions will be presented. Though the sound propagation model described in ASJ RTN-2008 can handle also special geometric situations, it satisfies with an acceptable computing speed. It could therefore rightly be regarded as forward-looking for future standards and calculation methods. It would be desirable that a solution for the problems we encountered during the implementation of ASJ CN-2007 will be included in the next revision.