Author : Anonim
Publisher : Unknown
Page : 178 pages
File Size : 51,6 Mb
Release : 2005
Category : Atmospheric turbulence
ISBN : UCBK:C101137994
Atmospheric Effects Associated with Highway Noise Propagation by Anonim Pdf
The primary questions investigated in this project were: What are the atmospheric conditions in the Phoenix valley that contribute to higher than normal sound levels? Are the conditions unique to the Phoenix valley? Can the atmospheric effects be anticipated? The main components of the project were: (1) a review of literature relevant to sound propagation, (2) detailed noise measurements in a Scottsdale neighborhood along the East Loop 101 Freeway, (3) computer modeling of sound propagation under various measured and inferred atmospheric conditions, (4) noise measurements before and after installation of an asphalt rubber friction course (ARFC) on the Pima Freeway by the ADOT Quiet Pavement Pilot Program, and (5) a pilot study investigating parametric models of tire/pavement noise. Some key conclusions are: nighttime thermal inversion conditions that are common in the Phoenix valley from October through March cause sound level increases of 5 to 8 dB at distances greater than 1/4 mile from freeways, nighttime down-slope drainage flows off the mountain ranges surrounding the Phoenix valley cause localized focusing and de-focusing of sound levels, sound level variations under inversion conditions appear to be greatest at locations that are upwind relative to the down-slope flows, the highest sound levels during the October to March period will usually occur right around sunrise when high traffic volumes coincide with strong inversion conditions, and installation of the ARFC reduces sound levels by 8 to 10 dBA both close to the roadway and at distances of 1/4 mile and greater. A final tentative conclusion is that, based on the computer modeling, there may be a rapid onset of refraction effects between about 200 and 300 m (650 to 1000 ft) from Phoenix valley roadways,
