Keywords

Absorptive materials, Absorptive treatments, Insertion loss degradation, Parallel barriers, Single barriers, Sound reflections, Traffic noise barriers, Traffic noise control

Abstract

In this thesis, the parallel barrier analysis feature in the Federal Highway Administration Traffic Noise Model (FHWA TNM), which is based on RAYVERB was used to explore the effects of multiple reflections due to single and parallel barriers and the use of absorptive treatment. Database was developed from the data collected from previous research efforts was used to generate a best fit equation model that can be used as a predetermining tool to determine the magnitude of parallel barrier insertion loss. The best fit equation model was then used to test against measured/model result and TNM prediction results for its validity. Absorptive materials were also studied such that 3 top of them were selected and recommended for Florida highway barrier use. It was found that the top three absorptive treatments for use on Florida highway barriers have been determined to be cementitous material, metal wool and glass fiber. These materials can be used to reduce the sound reflections for single and parallel barriers. The developed best fit equation model from this research is Deg = -2.17NRC - CW[superscript 0.42] + 1.97eln(BH) + RH[superscript 0.29] + DBB[superscript 0.27]; the prediction results give moderately high R[superscript 2] value of 0.55 if compared to the results from database. Prediction results from best fit equation model was also found to be consistent with the results from the measure/modeled results, providing further proof of the validity of the model. However, if compared results from equation model, TNM and measured/model (measured and model compared results using ANSI method), TNM was shown to provide higher insertion loss degradation. It was found that the most effective placement of absorptive material was the pattern which covers the barrier from the bottom up; it was also found that only about 60% from the bottom of the barrier area requires covering with high NRC absorptive treatment (NRC greater than or equals to 0.8) without sacrificing insertion loss. Also, if the barrier area near the top includes an easily obtainable NRC value of 0.4, only 40% to 50% of the bottom barrier needs absorptive treatment with a higher, more expensive NRC rating. These findings can substantially reduce the cost of conventional absorptive barrier which have full coverage of high NRC absorptive treatment. This research has begun important improvements in noise barrier design, additional work can be continued to further verify all the findings in this thesis such that easier and better equation model can be developed to calculate insertion loss degradation and cheaper absorptive barrier with less absorptive material usage can be built.

Notes

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Graduation Date

2004

Semester

Spring

Advisor

Wayson, Roger

Degree

Master of Science (M.S.)

College

College of Engineering and Computer Science

Department

Civil and Environmental Engineering

Degree Program

Civil and Environmental Engineering

Format

application/pdf

Identifier

CFE0000008

URL

http://purl.fcla.edu/fcla/etd/CFE0000008

Language

English

Release Date

May 2004

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Subjects

Dissertations, Academic -- Engineering and Computer Science; Engineering and Computer Science -- Dissertations, Academic

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