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Pages 80-87

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From page 80...
... 80 Conclusions How does the weather affect the sound we hear from highways? As this research study has shown, the weather can have a substantial impact on highway sound propagation.
From page 81...
... Conclusions and Suggested Research 81 and the afternoons were characterized by unstable atmospheric conditions with temperatures decreasing with height. The data show that the sound speed profile is highly correlated with these effects.
From page 82...
... 82 How Weather Affects the Noise You Hear from Highways the order of -6 to +8 dB, although the measurements conducted did not cover all of the combinations of Harmonoise wind and stability classes. Variations in vehicle mix and ground type did not have a significant impact on the Harmonoise modeled results.
From page 83...
... Conclusions and Suggested Research 83 • Research models, such as PE models, are useful in that they provide highly accurate results when the downrange and vertical sound speed profile can be quantified. However, they are not appropriate for regulatory use, as they are difficult to implement, require extensive meteorological data, and require significant processing power.
From page 84...
... 84 How Weather Affects the Noise You Hear from Highways in NWS websites or other weather data depositories. However, all states use the AERMOD air quality dispersion model and its required met data files from AERMET.
From page 85...
... Conclusions and Suggested Research 85 SHAs could also use look-up tables -- like those developed for this research or those included in NCHRP Report 791 -- to better understand the effects at a study location. As discussed previously, the research team believes that adjustments based on measured data are most accurate.
From page 86...
... 86 How Weather Affects the Noise You Hear from Highways Suggestions The results of this research study clearly show that the weather can affect traffic noise levels. This research study has created tools to quantify these effects and help explain these effects to the public.
From page 87...
... Conclusions and Suggested Research 87 • Follow-up evaluations. Evaluations of additional sites using a range of feasibility and reasonableness assumptions to expand understanding of the effects on noise impacts and abatement conclusions.

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