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Dispersion at the Edges of Near Road Noise Barriers
Citation:
Venkatram, A., D. Heist, S. Perry, AND L. Brouwer. Dispersion at the Edges of Near Road Noise Barriers. Atmospheric Pollution Research. Turkish National Committee for Air Pollution Research and Control, Izmir, Turkey, 12(2):367-374, (2021). https://doi.org/10.1016/j.apr.2020.11.017
Impact/Purpose:
Both the analysis of wind-tunnel data and the associated parameterizations described in the journal article for noise barrier edge effects provide important information for the development of improved dispersion models for roadway applications. These new algorithms are anticipated to be included in future releases of AERMOD as alpha options, which, upon further evaluation may be included in the regulatory version of the model. AERMOD is the agency’s preferred model for many regulatory applications and is used by OAQPS, OTAQ, Regions and States for roadway applications. Specifically, this would allow the consideration of the mitigative potential of these roadway configurations in modeling assessments.
Description:
This paper presents an analysis of data from a wind tunnel study conducted to examine the dispersion of emissions at the edges of near-road noise barriers. The study is motivated by the concern that a barrier positioned downwind of a roadway may guide highly polluted plumes along the barrier leading to heightened concentrations as the plume spills around and downwind of the barrier end. The wind tunnel database consists of measurements of dispersion around a simulated roadway segment with various noise barrier configurations. Each roadway segment simulated in the wind tunnel had full-scale equivalent dimensions of 135 m long. Barrier segments, 135 m long with a height (H) of 6 m, were located on the downwind side of the source at a distance of 18 m from it (measured perpendicularly from the line source). Examination of the concentration patterns associated with the cases indicates that 1) vertical mixing induced by barriers persists at crosswind distances up to the edge (lateral end) of the barrier and downwind distances of x/H = 10, 2) concentration levels at all heights below z/H = 1 increase towards the edge of the barrier at downwind distances less than x/H = 7, and 3) concentration is well mixed in the vertical at the edge of the barrier, and the levels can be higher than in the middle of the barrier even when the source ends at the edge of the barrier. We have formulated a parameterization that captures the major features of these observations and can be incorporated in models such as RLINE.
URLs/Downloads:
DOI: Dispersion at the Edges of Near Road Noise Barriers
https://www.sciencedirect.com/science/article/pii/S1309104220303408?via%3Dihub