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FHWA Traffic Noise Model (FHWA TNM®) User's Guide

Final Report January 1998

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Prepared for
U.S. Department of Transportation
Federal Highway Administration
Office of Environment and Planning
Washington, DC 20590

Prepared by
U.S. Department of Transportation
Research and Special Programs Administration
John A. Volpe National Transportation Systems Center
Acoustics Facility
Cambridge, MA 02142-1093


This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification, or regulation.

The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this document.


This User's Guide is for the Federal Highway Administration's Traffic Noise Model (FHWA TNM®), Version 1.0 -- the FHWA's computer program for highway traffic noise prediction and analysis. Two companion reports, a Technical Manual and a data report, respectively, describe the acoustics and the vehicle noise-emissions database within TNM.

The User's Guide first lists TNM's hardware/software requirements, instructs how to install the program and an optional digitizer, and discusses TNM's file structure. Next it provides definitions of commonly used terminology. Finally, it details each TNM menu item, including overviews of all TNM procedures: Setup, Input, Calculate, Barrier Analysis, Parallel Barriers, and Contours.

Also included are the following appendices: FHWA Policy, Details of All Input Types, Input-error Messages, Comparison of TNM with STAMINA 2.0/OPTIMA, Certified Output for the Official TNM Test Case, and REMEL Data Base.


This User's Guide is for the Federal Highway Administration's Traffic Noise Model (FHWA TNM®), Version 1.0 -- the Federal Highway Administration's computer program for highway traffic noise prediction and analysis. A companion Technical Manual describes the acoustics within TNM, Version 1.0.1 In addition, a companion technical report documents the vehicle noise-emissions database within TNM.2

Overview of TNM: TNM computes highway traffic noise at nearby receivers and aids in the design of highway noise barriers. As sources of noise, it includes 1994-1995 noise emission levels for the following cruise-throttle vehicle types:

In addition, TNM includes full-throttle noise emission levels for vehicles on upgrades and vehicles accelerating away from the following traffic-control devices:

TNM combines these full-throttle noise emission levels with its internal speed computations to account for the full effect (noise emissions plus speed) of roadway grades and traffic-control devices.

TNM propagates sound energy, in one-third-octave bands, between highway systems and nearby receivers. Sound propagation takes the following factors into account:

TNM computes the effect of intervening ground (defined by its type, or optionally by its flow resistivity) with theory-based acoustics that have been calibrated against field measurements. In addition, TNM allows sound to propagate underneath selected intervening roadways and barriers, rather than being shielded by them.

During calculation, TNM perturbs intervening barriers up and down from their input height, to calculate for multiple heights. Then during acoustical design of selected barriers, combined with selected receivers, TNM displays sound-level results for any combination of height perturbations. It also contains an input-height check, to determine if noise barriers break the lines-of-sight between sources and receivers. In addition, it provides summary cost and benefit information for each barrier design, from user-supplied unit barrier costs and land-use information.

For selected cross sections, TNM also computes the effect of multiple reflections between parallel barriers or retaining walls that flank a roadway. The TNM user can then enter the computed parallel-barrier degradations as adjustment factors for individual receivers in TNM's calculation of receiver sound levels.

TNM computes three measures of highway traffic noise:

TNM computes these three noise measures at user-defined receiver locations, where it also computes several diagnostics to aid in noise-barrier design. In addition, it computes three types of contours:

TNM runs under Microsoft® Windows Version 3.1 (or later). Within Windows, it allows digitized input using a generic Windows digitizer driver, plus the import of DXF files from CAD programs and input files from STAMINA 2.0/OPTIMA. Note: TNM will run under Microsoft® Windows 95 or Windows NT, however, TNM is a 16-bit program and will not take full advantage of the 32-bit architecture associated with Windows 95 or NT.

To aid during input and to document the resulting input and barrier designs, TNM shows the following graphical views:

One aspect of TNM which will enhance usability substantially is that most graphics, input dialogs, and output tables are dynamically linked. In other words, if you have a TNM Plan View on your computer display, as well as a roadway input dialog, you can select the roadway graphically (see Section 5.5), move it to a new location (see Section 5.7), and the new coordinates will be reflected in the input dialog in real time. Similarly, if you have a TNM Barrier Perspective View on your computer display, as well as a Diagnosis by Barrier Segment table, you can select a barrier segment graphically (see Section 5.5), move it up and down (see Section 10.6), and the associated barrier costs will change accordingly.

TNM Version 1.0 replaces FHWA's prior pair of computer programs, STAMINA 2.0/OPTIMA. In addition, TNM's technical manual replaces FHWA's prior prediction model: FHWA Highway Traffic Noise Prediction Model, FHWA-RD-77-108.3

Organization of this User's Guide:

Section 1.Getting Started: Discusses TNM's hardware and software requirements, program and digitizer installation, and TNM's file structure;

Section 2.Terminology: Presents pertinent terminology used throughout the User's Guide.

Section 3.Overview of Program: Overviews all TNM procedures: Setup, Input, Calculate, Barrier Analysis, Parallel Barriers, and Contours;

Section 4.File Menu: Discusses how to open, save, import, and print files;

Section 5.Edit Menu: Describes TNM's editing options and CAD-like capabilities;

Section 6.View Menu: Describes TNM graphical views and their creation and manipulation;

Section 7.Setup Menu: Details the entry of TNM user information and preferences, plus the registration of plans and profiles on the digitizer;

Section 8.Input Menu: Details the entry of TNM input: roadways, receivers, barriers, building rows, terrain lines, ground zones, tree zones, and contour zones;

Section 9.Calculate Menu: Discusses TNM's sound-level calculations;

Section 10.Barrier Analysis Menu: Details the acoustical design of noise barriers;

Section 11.Parallel Barriers Menu: Discusses input and computation of parallel-barrier degradation for barriers or retaining walls that flank a roadway;

Section 12.Contours Menu: Discusses input and computation of contours;

Section 13.Tables Menu: Discusses the available output tables for viewing and printing;

Section 14.Window Menu: Discusses options for rearranging and closing open windows; and

Section 15.Help Menu: Discusses the different help options available to the user.

This guide concludes with the following appendices:

Appendix A.FHWA Policies for Highway Traffic Noise Prediction Using TNM;

Appendix B.Details of All Input Types;

Appendix C.Input-error Messages;

Appendix D.Comparison of TNM with STAMINA 2.0/OPTIMA;

Appendix E.Certified Output for the Official TNM Test Case;

Appendix F.REMEL Data Base;



FHWA TNM Announcement and Order Form

FHWA TNM Registration Card


FHWA TNM® was developed in part by:

U.S. Department of Transportation
Federal Highway Administration

Robert Armstrong, Steven Ronning, Howard Jongedyk.

U.S. Department of Transportation
John A. Volpe National Transportation Systems Center, Acoustics Facility

Overall management, emission-data design/measurement/analysis, propagation-path development, program testing, User's Guide, Technical Manual, TNM Trainer CD-ROM:

Gregg Fleming, Amanda Rapoza, Cynthia Lee, David Read, Paul Gerbi, Christopher Roof, Antonio Godfrey, Shamir Patel.

Harris Miller Miller & Hanson Inc.

Technical management, emission-analysis design, functional requirements, conceptual program design, acoustical algorithms, design/development/testing of acoustical code and vertical geometry, User's Guide, Technical Manual:

Grant Anderson, Christopher Menge, Christopher Rossano, Christopher Bajdek, Thomas Breen, Douglas Barrett, William Robert.

Foliage Software Systems, Inc.

Program design/specification/development/testing, development of horizontal geometry and interfaces, program documentation:

Ronald Rubbico, George Plourde, Paul Huffman, Christopher Bowe, Nathan Legvold.

Special contributors:

Vanderbilt University: William Bowlby -- emission-data design/measurement/analysis, vehicle speeds.4
Bowlby & Associates, Inc.: William Bowlby -- TNM Trainer CD-ROM
Serac Technology Group, Inc.: Theodore Patrick -- TNM Trainer CD-ROM
University of Central Florida: Roger Wayson -- emission-data design/measurement/analysis.
Florida Department of Transportation: Win Lindeman -- Funding and management of subsource-height study.
Florida Atlantic University: Stewart Glegg, Robert Coulson -- subsource height measurements.5
Maryland State Highway Administration: Kenneth Polcak -- emission data.
Ohio University: Lloyd Herman -- emission data.
Emission-data state agencies: California, Connecticut, Florida, Kentucky, Maryland, Massachusetts, Michigan, New Jersey, Tennessee.

Design and Review Panel:

Domenick Billera, James Byers, Rudy Hendriks, Harvey Knauer, Win Lindeman, William McColl, Kenneth Polcak.

National Pooled-Fund Contributing States:

Arizona, California, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New York, North Carolina, Ohio, Oregon, Pennsylvania, Tennessee, Texas, Utah, Virginia, Washington and Wisconsin.

The development work of Harris Miller Miller & Hanson, Foliage Software Systems, Vanderbilt University and the University of Central Florida was conducted in part under contract to Foster-Miller, Inc. Vanderbilt University and the University of Central Florida were also under contract to the Volpe Center.

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