A new version of TNM, Version 2.5, is now available. TNM 2.5 is the first version of the software, since the original release, with major improvements to the acoustics. Users should expect to see predicted sound levels that are different than sound levels predicted with previous versions of TNM. For more information about TNM 2.5, please view the TNM 2.5 information page at:

http://www.trafficnoisemodel.org/Version_25.html  

TNM 2.5 includes the following:

Changes in the acoustics

TNM 2.5 was developed to address the following issues: 1) the over-prediction found in the TNM Validation Phase 1 data results; and 2) an anomaly related to diffraction points. Steps taken to address these issues include:

1. An improvement was made to the implementation of the vehicle emission level database - a more comprehensive methodology was applied in correcting the measured emission levels back to the source; and
2. A bug in the acoustics code was identified and corrected, where related diffraction algorithm parameters were improved.

You can access more information on the TNM web site at:

http://www.thewalljournal.com/a1f04/tnm/

The FHWA TNM is a state-of-the-art computer program used for predicting noise impacts in the vicinity of highways. 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.

The FHWA TNM contains the following components:

• Modeling of five standard vehicle types, including automobiles, medium trucks, heavy trucks, buses, and motorcycles, as well as user-defined vehicles.

• Modeling of both constant-flow and interrupted-flow traffic using a 1994/1995 field-measured database.

• Modeling of the effects of different pavement types, as well as the effects of graded roadways.

• Sound level computations based on a one-third octave-band database and algorithms.

• Graphically interactive noise barrier design and optimization.

• Attenuation over/through rows of buildings and dense vegetation.

• Multiple diffraction analysis.

• Parallel barrier analysis.

• Contour analysis, including sound level contours, barrier insertion loss contours, and sound-level difference contours.

These components are supported by a scientifically founded and experimentally calibrated acoustic computation methodology, as well as an entirely new, and more flexible database, as compared with that of its predecessor. STAMINA 2.0/OPTIMA. The database is made up of over 6000 individual pass-by events measured at forty sites across the county. It is the primary building block around which the acoustic algorithms are structured.

The most visible difference between the FHWA TNM and STAMINA 2.0/OPTIMA, is TNM’s Microsoft Windows interface. Data input is menu-driven using a digitizer, mouse, and/or keyboard. Users also have the ability to import STAMINA 2.0/OPTIMA files, as well as roadway design files saved in CAD, DXF format. Color graphics will play a central role in both case construction and visual analysis of results.

The recommended computer system requirements for TNM are:

• Microsoft® Windows 98/NT/2000/XP

• 500 MHz Intel® Pentium or equivalent, Pentium III recommended

• 32 MB of RAM or above recommended

• 10 MB of available hard-disk space for installation

• Up to 1 MB of available hard-disk space for each TNM run

• Super VGA (1024 x 768), 16-bit colors, configured with "small" fonts

• CD-ROM compatible drive

To digitize coordinates from plan sheets and roadway profiles, the following is required:

• Digitizer: Any manufacturer/model that meets the 1/CS/Telegraphics Wintab Interface Specification, preferably with a 16-button puck. The digitizer manufacturer should provide the file WINTAB.DLL, which must be resident on the hard disk for digitizer use.

FHWA Traffic Noise Model (#TNM25) is available from McTrans at LOS 1 for $695, which includes the TNM User's Guide and TNM Technical Manual. Registered users of TNM 2.0 and 2.1 may receive this upgrade at no charge. Users who purchased any version of TNM on or after March 1, 2002, may also obtain the 2.5 upgrade at no charge.

The processing fee ($10) is waived for online orders using Visa or MasterCard.

Order Traffic Noise Model Version 2.5 Now!