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N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 791 Supplemental Guidance on the Application of FHWAâs Traffic Noise Model (TNM) Harris Miller Miller & Hanson Inc. Burlington, MA Bowlby & Associates, Inc. Franklin, TN Environmental Acoustics Lemoyne, PA Grant S. Anderson Concord, MA Douglas E. Barrett Keene, NH Subscriber Categories Highways â¢ Design â¢ Environment TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2014 www.TRB.org Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Boardâs recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 791 Project 25-34 ISSN 0077-5614 ISBN 978-0-309-30797-0 Library of Congress Control Number 2014948779 Â© 2014 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of the report.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. C. D. Mote, Jr., is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Victor J. Dzau is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academyâs purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. Mote, Jr., are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Boardâs varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individu- als interested in the development of transportation. www.TRB.org www.national-academies.org
C O O P E R A T I V E R E S E A R C H P R O G R A M S AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 25-34 by Harris Miller Miller & Hanson Inc. (HMMH) as the lead organization for the research. HMMH was also the lead for research topics Wind and Temperature Gradients and Tunnel Openings. Christopher W. Menge, Principal Con- sultant, was the Principal Investigator and a lead author. Other HMMH authors included Christopher J. Bajdek, Principal Consultant; Timothy M. Johnson, Senior Consultant; Bradley L. Nicholas, Senior Consultant; J. Eric Cox, Senior Consultant; and James E. Ferguson III, Senior Consultant. Subconsultants to HMMH included the following firms and individuals: Bowlby & Associates, Inc., was the lead organization for the research topics Signalized Interchanges, Intersections, and Roundabouts; Building Rows; and Parallel Barriers. The authors were William Bowlby, Ph.D., P.E., and Geoffrey Pratt, P.E., with assistance from R. Clay Patton and Darlene Reiter, Ph.D., P.E. Environmental Acoustics, A Division of Gannett Fleming Inc., was the lead organization for the research topics Structure-Reflected Noise and Expansion-Joint Noise, Median Barriers, and Multilane Highways. The authors included Harvey S. Knauer, P.E., and Ahmed A. El-Aassar, Ph.D., P.E. Grant S. Anderson was the lead author for the research topics Topography, Ground Zones, and Tree Zones. Douglas E. Barrett was the lead author for the research topic Area Sources. Herb Singleton, P.E., of Cross-Spectrum Acoustics LLC provided support for noise measurements and data analysis. CRP STAFF FOR NCHRP REPORT 791 Christopher W. Jenks, Director, Cooperative Research Programs Christopher Hedges, Manager, National Cooperative Highway Research Program Lori L. Sundstrom, Senior Program Officer Megan A. Chamberlain, Senior Program Assistant Eileen P. Delaney, Director of Publications Ellen M. Chafee, Editor NCHRP PROJECT 25-34 PANEL Field of Transportation PlanningâArea of Impact Analysis Timothy V. Sexton, Washington State DOT, Seattle, WA (Chair) Thomas F. Hanf, Michigan DOT, Lansing, MI Mike Hankard, Hankard Environmental, Verona, WI H. Wayne Jones, Asphalt Institute, Columbus, OH Kenneth D. Polcak, Maryland State Highway Administration, Baltimore, MD Bruce C. Rymer, California DOT, Sacramento, CA Robert N. Saikaly, CDM Smith, Pittsburgh, PA Brian L. Schleppi, Ohio DOT, Columbus, OH Larry A. Scofield, International Grooving and Grinding Association, Mesa, AZ Danielle Shellenberger, Pennsylvania DOT, Harrisburg, PA Adam T. Alexander, FHWA Liaison Christine Gerencher, TRB Liaison
F O R E W O R D By Lori L. Sundstrom Staff Officer Transportation Research Board This report provides state departments of transportation (DOTs) staff and other trans- portation professionals with technical guidance on using the FHWA Transportation Noise Model (TNM) to model traffic-generated noise in a variety of settings that have not been addressed by TNM. This report should be of immediate use to experienced users of TNM by helping them to improve the accuracy and precision of their modeling results and inform decision-making related to the design of noise abatement measures. Noise is an important environmental consideration for highway planners and designers, and through 2007, state highway agencies have spent $4.5 billion to abate the noise generated by federal-aid highway projects. Transportation agencies assess different aspects of highway noise to determine or predict community impacts during transportation planning, although procedures have varied from program to program and agency to agency. To aid states in com- plying with FHWAâs noise policies and regulations, FHWA developed and improved a series of computerized noise prediction models beginning in the 1970s. FHWAâs TNM is a computer program used for predicting noise levels and therefore impacts in the vicinity of highways, and it uses advances in personal computer hardware and software to improve upon the accuracy and ease of modeling highway noise, including the design of effective, cost-efficient highway noise barriers. FHWA has provided substantial guidance for the routine application of TNM but sce- narios exist for which there is no technical guidance. Out of necessity and without technical guidance, TNM users have independently developed techniques to assemble and input data into the TNM to analyze these scenarios. Typically these techniques have not been validated with field measurements, and the accuracy of their results is unknown. Accurate results are necessary to help DOTs make consistent and cost-effective noise abatement decisions and provide reliable modeling results to the public. Under NCHRP Project 25-34, Harris Miller Miller & Hanson Inc. was asked to identify best practices and to supplement existing guidance on applying TNM to accurately, consistently, and efficiently model (1) structure-reflected noise; (2) bridge expansion joints; (3) signalized interchanges; (4) intersections; (5) area sources, e.g., weigh stations, park and ride lots, toll facilities, and service plazas; (6) median barriers; and (7) roundabouts. This research deter- mined the sensitivity and accuracy of methods to model (1) multilane highways, (2) rows of buildings, (3) topography, (4) ground zones, and (5) tree zones, and identified best practices for input parameters. The research also synthesized the state of practice for analyzing the effects of wind direction and temperature inversion on sound propagation. The report is organized by scenario, and experienced transportation analysts, modelers, and designers should find this guidance immediately useful in using TNM to model noise impacts under these scenarios.
Practitioners interested in the information, studies, modeling practices, and results that were evaluated to develop the guidance provided in NCHRP Report 791 may wish to consult Appendices A through L of the contractorâs final report, which were prepared to accompany each of the research topic areas and are available on the NCHRP Project 25-34 web page at http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=2986.
C O N T E N T S 1 Summary 2 Chapter 1 Introduction 2 1.1 Introduction to NCHRP Project 25-34 2 1.2 Purpose and Content of NCHRP Report 791 and Supporting Appendices 3 Chapter 2 Structure-Reflected Noise and Expansion-Joint Noise 3 2.1 Introduction 3 2.2 Modeling Techniques Evaluated 11 Chapter 3 Signalized Interchanges, Intersections, and Roundabouts 11 3.1 Introduction 12 3.2 Modeling Acceleration and Deceleration 14 3.3 Research Tasks 15 3.4 Outcomes of the ResearchâBest Practices and How to Implement Them for a Noise Study or TNM Model 31 Chapter 4 Area Sources 31 4.1 Stationary Sources 36 4.2 Accelerating and Decelerating Traffic 40 Chapter 5 Median Barriers 40 5.1 Introduction 40 5.2 Measurement Locations Evaluated 41 5.3 Modeling Techniques Evaluated 43 5.4 Best Modeling Practices 43 5.5 Conclusions 45 Chapter 6 Multilane Highways 45 6.1 Introduction 45 6.2 Measurement Locations Evaluated 46 6.3 Evaluation of Modeling Techniques 48 6.4 Best Modeling Practices 49 Chapter 7 Building Rows 49 7.1 Research Approach 51 7.2 Outcome of the ResearchâBest Practices and How to Implement Them for a Noise Study or TNM 65 Chapter 8 Topography 65 8.1 Outside Edge of Pavement: Horizontal Precision 65 8.2 Required Terrain Lines along Elevated Roadways 66 8.3 Minimum Terrain Line Spacing
66 8.4 Terrain Lines: Vertical Precision 66 8.5 Barrier Tops: Vertical Precision 67 8.6 Flat-Top Berms 69 Chapter 9 Ground Zones 69 9.1 Size and Location of Ground Zones 69 9.2 Expanded List of Ground Types 71 9.3 Bodies of Water 72 Chapter 10 Tree Zones 72 10.1 Overlaid Loose-Soil Zone Not Needed with Tree Zones 72 10.2 Guidance for Narrow Tree Zones 72 10.3 Attenuation Dependence on Visibility through Tree Zones 74 Chapter 11 Wind and Temperature Gradients 74 11.1 Introduction 74 11.2 Research Approach 76 11.3 Research Tasks 76 11.4 Outcome of the ResearchâEffect of Wind Speed and Direction and Temperature Gradients on Highway Noise Sources 82 11.5 Combined Effects of Wind and Temperature Gradients on Highway Noise Sources 83 Chapter 12 Parallel Barriers 83 12.1 Research Approach 85 12.2 Outcome of the ResearchâBest Practices and How to Implement Them for a Noise Study or TNM Model 91 Chapter 13 Tunnel Openings 91 13.1 Introduction 91 13.2 Modeling Techniques Evaluated 96 13.3 Best Modeling Practices for Tunnel Openings 100 13.4 Conclusions 101 Appendices A through L