NoiseMap Forums
NoiseMap Software => Support => Topic started by: roger on August 13, 2013, 11:35:31 AM
-
NoiseMap calculates in accordance with CRTN, which assumes barriers to be infinitely long. We’re considering some barriers of short length (<50m), would you have suggestions for the consideration of edge effect due to barrier end diffraction (and thus reduction in CRTN calculated barrier effect)?
As you say, CRTN does not deal with this effect, and NoiseMap implements CRTN as exactly as possible.
In most cases, where there is a short length of barrier, the receiver point will be exposed to noise from the parts of the road that extend beyond the end of the noise barrier. In this case, the diffraction around the end is negligible compared to the noise coming from the unscreened part of the road. Also, the path difference over the top of the barrier is normally small, so that the noise coming over the top soon masks any noise coming round the end.
In practical cases, we have not found that any significant inaccuracy is caused by ignoring the diffraction round the end of the barrier.
Roger