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From page 147... ... A-3 S U M M A R Y Literature Review This appendix presents the literature review conducted for NCHRP Project 25-44, "Field Evaluation of Reflected Noise from a Single Noise Barrier." It addresses the community noise issues that have led to investigations of noise reflected from barriers, past attempts to quantify the magnitude and effects of noise reflected from barriers, and the success of efforts to reduce noise reflected from barriers. Community noise issues that have led to the investigations of noise reflected from barriers nearly date back to the first widespread construction of U.S. Read the entire page →
From page 148... ... A-4 vehicle pass-bys.5 Recently, studies have begun to examine further influences that may be perceived by residents in addition to changes in the A-weighted sound level. The success of efforts to reduce noise reflected from barriers has varied across the United States, in part due to the different approaches pursued by various state highway agencies. Read the entire page →
From page 149... ... A-5 C H A P T E R A - 1 Introduction to Appendix A This appendix reviews available literature on reflected noise from single noise barriers and addressed the following: • The community noise issues that have led to investigations of noise reflected from barriers. • Past attempts to quantify the magnitude and effects of noise reflected from barriers. Read the entire page →
From page 150... ... A-6 C H A P T E R A - 2 Community Noise Issues That Have Led to Investigations of Noise Reflected from Barriers Overview Community noise issues that have led to the investigations of noise reflected from barriers nearly date back to the first widespread construction of highway noise barriers in the United States in the 1970s. By the end of 2010, over 180 million sq. Read the entire page →
From page 151... ... A-7 The California Department of Transportation (Caltrans) , one of the leaders in constructing noise barriers for nearly four decades, has received and responded to complaints of reflected sound for almost that entire time. Read the entire page →
From page 152... ... A-8 detailed investigations because "these situations have fallen outside of their policy guidelines" and also because of "their lack of a funding mechanism to provide additional mitigation."24 Summaries of Cited Works (Community noise issues that have led to investigations of noise reflected from barriers) Menge, C.W. Read the entire page →
From page 153... ... A-9 less than 0.5 dB."26 Although "conventional wisdom holds that small differences in sound levels are more difficult to perceive in environmental rather than laboratory settings," the paper contends that other factors may influence listeners' perceptions and sensitivities, increasing the likelihood both that they will notice changes and perceive the changes as increases in level attributed to reflections from a new noise barrier: • Long-term exposure to a particular noise source like a nearby highway may lead to ingrained expectations regarding typical noise levels and heightened sensitivity to even small changes. • Comparative audio listening tests have demonstrated that frequency shifts as small as 0.1 dB are audible. Read the entire page →
From page 154... ... A-10 Hendriks, R Read the entire page →
From page 155... ... A-11 Burge, P., J Crawford, and Peter Wasko, "Use of advanced tools and techniques to resolve an atypical parallel noise barrier case," Proceedings of Noise-Con 2013, Denver, CO, August 26-28, 2013 As part of a lane addition project along Interstate 94 (I-94) Read the entire page →
From page 156... ... A-12 concluded the sound walls would not have significant effects. Public-outreach efforts by the Orange County Transportation Authority went beyond state and federal requirements, Caltrans said." Swegles, F., "A quest for peace and quiet," Orange County Register, September 25, 2013 Although Caltrans agreed to use a sound-absorbing concrete block product on noise barriers to be built as part of a $275 million freeway widening that will begin in 2014 in north San Clemente, residents in south San Clemente still are complaining of noise reflected from a 16-ft noise barrier constructed in 2011. Read the entire page →
From page 157... ... A-13 were unfounded." Noise reflection has not been a significant issue in Florida and they have not done any research/studies in that area. Correspondence with Timothy Sexton, Washington State Department of Transportation, November 4 and 25, 2013 WSDOT has "received complaints on this topic, but staff time limitations restrict their ability to respond in person to all complaints." Since these situations have fallen outside of their policy guidelines, WSDOT has decided not to collect measurements or pursue a detailed explanation. Read the entire page →
From page 158... ... A-14 C H A P T E R A - 3 Past Attempts to Quantify the Magnitude and Effects of Noise Reflected from Barriers Overview Over the past several decades, state highway agencies have made numerous attempts to quantify the magnitude and effects of noise reflected from highway noise barriers. In 1978, in response to complaints about increased noise from residents opposite a newly constructed noise barrier along US 101 in San Jose, Caltrans performed one of the first investigations of sound reflected from a highway noise barrier. Read the entire page →
From page 159... ... A-15 these studies on a routine basis because of their high cost, both in terms of money and necessary resources."30 In 1999, Caltrans conducted another measurement program in conjunction with the construction of new noise barriers along Interstate 680 in Alamo, California, using the guidelines described above. To evaluate noise level changes, before-and-after noise levels were grouped into similar meteorological categories and compared. Read the entire page →
From page 160... ... A-16 Therefore, it is possible that the studies, while accurately quantifying the magnitude of the change in overall sound level due to reflections, were not addressing the effects of reflected noise perceived by residents. Other recent studies have begun to look at additional factors, including spectral information, that may be perceived by community members. Read the entire page →
From page 161... ... A-17 Summaries of Cited Works (Past attempts to quantify the magnitude and effects of noise reflected from barriers) Menge, C.W. Read the entire page →
From page 162... ... A-18 counts. Noise levels were measured near the highway as well as in neighborhoods more than 1,000 ft. Read the entire page →
From page 163... ... A-19 differences in noise levels "before" and "after" the installation of the noise barriers at locations relatively distant from the freeway traffic noise source. The measurement program followed guidelines developed by Caltrans (Technical Advisory TAN-9701-R9301, a predecessor to TAN-98-01-R9701) Read the entire page →
From page 164... ... A-20 three of the four measurement sites. At the fourth site, however, the analysis indicated a statistically significant increase of approximately 0.5 dBA due to construction of the noise barrier. Read the entire page →
From page 165... ... A-21 this material on existing noise walls. Provide recommendations on the most appropriate use of sound-absorptive materials that will ensure ODOT a return on investment from the initial higher construction costs of these types of walls. Read the entire page →
From page 166... ... A-22 strength using a reference microphone. The reflective noise barrier was used as the control, and the measured difference in sound pressure level between it and each of the three absorptive barriers was attributed to the absorptive surfaces. Read the entire page →
From page 167... ... A-23 C H A P T E R A - 4 The Success of Efforts to Reduce Noise Reflected from Barriers Overview The success of efforts to reduce noise reflected from barriers has varied across the United States, in part due to the different approaches pursued by various state highway agencies. As described in Chapters A-2 and A-3, some DOTs have responded to community concerns about sound reflected from noise barriers by conducting investigations to attempt documenting perceived increases in noise. Read the entire page →
From page 168... ... A-24 • In its Environmental Procedures Manual, the Tennessee Department of Transportation (TDOT) acknowledges that "noise reflections off of a noise barrier on one side of a highway can . Read the entire page →
From page 169... ... A-25 (1 to 2.5 dB) at closer receptors.51 This project involved parallel barriers, but some of the findings are relevant to measurement studies of single-barrier reflections. Read the entire page →
From page 170... ... A-26 policy in dealing with unwanted reflections from single [and parallel] noise barriers," having always used absorptive noise barriers in those situations. Read the entire page →
From page 171... ... A-27 absorptive noise barrier materials. TDOT also acknowledges that "noise reflections off of a noise barrier on one side of a highway can also increase sound levels on the opposite side of the highway." While stating that "in most cases, these increases are less than 3 dB which is usually the smallest change in hourly sound levels that people can detect without specifically listening for the change," TDOT may consider specifying single noise barriers as absorptive if there are noise-sensitive land uses on the opposite side of the road from the noise barrier.53 Wisconsin Department of Transportation Facilities Development Manual, Chapter 23 "Noise," Section 35 "Noise Abatement Measures," February 15, 1988 WisDOT states in its Transportation Facilities Development Manual that "the principles of acoustics indicate that sound reflected from the surface of a noise wall has the potential of increasing sound levels at existing noise-sensitive receptors located on the opposite side of the roadway from the proposed noise wall project. Read the entire page →
From page 172... ... A-28 • Presence of a retaining wall with a reflective surface on the side opposite the highway from the proposed reflective-surfaced noise barrier. • Presence of impacted receptors on the side opposite the highway for whom a noise barrier was not determined to be feasible or reasonable. Read the entire page →
From page 173... ... A-29 Donavan, Paul R Read the entire page →
From page 174... ... A-30 reflected noise to a "less than noticeable" level increase at the most economical cost. The advantage of the backless panel is that it would provide acoustical absorption without the added cost and weight provided by a solid back panel, which was not needed due to the mass of the existing barrier. Read the entire page →
From page 175... ... A-31 C H A P T E R A - 5 Conclusions for Appendix A This review of available literature regarding reflected noise from single, reflective barriers has focused on the following: (1) the community noise issues that have led to investigations of noise reflected from barriers, (2) Read the entire page →
From page 176... ... A-32 R E F E R E N C E S Berrios, Mariano, Florida Department of Transportation. Message to Douglas Barrett. Read the entire page →
From page 177... ... A-33 Roseen, M., Effects of a noise barrier, located on the west side of TH 47 (University Ave.) , on the noise levels of residences on the east side of TH 47 located between 45th Ave. Read the entire page →
From page 179... ... B-1 Phase 2 (Sound-Absorbing Barriers) -- Detailed Analysis and Results A P P E N D I X B William Bowlby, Rennie Williamson, and Clay Patton BowlBy & AssociAtes, inc. Read the entire page →
From page 180... ... B-2 CONTENTS CHAPTER B-1.....................................................................................................................................B-3 Introduction to Appendix B................................................................................................................................... B-3 CHAPTER B-2.....................................................................................................................................B-4 Study Locations..................................................................................................................................................... Read the entire page →

From page 147...

... A-3 S U M M A R Y Literature Review This appendix presents the literature review conducted for NCHRP Project 25-44, "Field Evaluation of Reflected Noise from a Single Noise Barrier." It addresses the community noise issues that have led to investigations of noise reflected from barriers, past attempts to quantify the magnitude and effects of noise reflected from barriers, and the success of efforts to reduce noise reflected from barriers. Community noise issues that have led to the investigations of noise reflected from barriers nearly date back to the first widespread construction of U.S.