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Traffic Noise Model: Frequently Asked Questions FAQs

General Information

  1. What are TNM's system requirements?

    The minimum recommended system requirements for the most current version of TNM are:

    • Microsoft® Windows 98, ME, NT, 2000, or 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

    NOTE: TNM 2.5 has been tested successfully on various Windows Vista and Windows 7 builds. Some users have reported problems with TNM, but in most cases resolve these issues by installing as an administrator and installing to the default location.

    The NMPLOT utility used to draw the sound level contours is not compatible with 64 bit operating systems.

    Minimum system requirements for older versions of TNM such as 1.0, 1.0b can be found on Page 2 of the TNM User's Guide.

  2. Where can I obtain TNM?

    TNM Version 2.5 can be downloaded free of charge at:

  3. What is the most recent version of TNM?

    The most recent version of TNM is Version 2.5 released in April, 2004.

  4. Can I run multiple versions of TNM on my computer?

    Yes, some users may want to switch from TNM 1.1 to 1.0b when calculating sound level contours, since 1.0b performs better with contour calculations. To run different multiple versions of TNM, install each version in its own unique directory. To install TNM 1.1 along side TNM 1.0b, for example, you'll need to assign each version a unique system file; prior to Version 2.0, TNM installations use the same system files. For instructions on how to install TNM 1.1 alongside an existing TNM installation.

  5. Where can I upgrade TNM from Version 1.0b to Version 1.1?

    Please send your user registration information to TNM Tech Support for verification. The support team will then provide you with a link to download the free upgrade.

  6. Where can I upgrade TNM from Version 1.0b to the most recent version, TNM 2.5?

    Owners of previous versions of TNM (1.0, 1.0a, 1.0b, 1.1) can purchase TNM 2.5 at the discounted price of $495.

  7. How do I configure my monitor display to work with TNM?

    You will need to set your computer monitor's resolution to 1024 x 768 or greater, 16 bit colors or greater, and the smallest available font size. You can usually accomplish this in the computer's Control Panel, Display, Settings function.

  8. Should I turn my computer screen saver off while running TNM?

    TNM sometimes crashes when certain screen savers start. If this happens, discontinue your screen saver when running TNM.

  9. What is a "move" data error during installation?

    TNM setup places some temporary files in your temp directory. This is usually C:\TEMP, but may be different for computers on a network. Copy the TNM installation file to your local C:\TEMP directory on your computer and run the file from there.

  10. Where can I obtain a copy of the TNM User's Guide 2.5 Addendum?

    The TNM User's Guide Addendum can be found on the TNM Version 2.5 web page or by clicking here.

  11. Where can I obtain technical support?

    Services are available to help you with your questions. Registered owners are entitled to receive technical support and information on upgrades and supplementary guides. For installation and supplementary guide information, users may contact the McTrans Center at (352) 392-0378 or For technical support, users are encouraged to take advantage of this Frequently Asked Questions page and other features in our support page. Users may also contact TNM technical support via email

  12. Do I have to use TNM?

    The FHWA TNM, Version 2.5, is the current model version. To comply with 23 CFR, Part 772.17 the FHWA TNM, Version 2.5 (or any other model determined by the FHWA to be consistent with the methodology of the FHWA TNM) is required to be used on all Federal-aid highway projects.

  13. Why does TNM Version 1.1 sometimes crash when I try to open an input dialog or an output table?

    A Microsoft® Windows 95/98/ME compatibility bug has been discovered in TNM Version 1.1. This error does not occur for Windows NT or Windows 2000 users. To avoid this error (after creating a new run and after calculating a run), close the run, then re-open it. All dialogs and tables will then open correctly. This has been corrected in TNM Version 2.0 and above.

  14. Is it possible to copy and paste multiple rows? TNM requires you to insert each row individually. Here is a trick:
    1. Randomly draw a multi-segment roadway (e.g., a 10 segment roadway) on plan view.
    2. In the input receiver dialogue you will see multiple rows created by this roadway. Now just cut and paste from your spreadsheet onto the dialogue box.

    You can also export a GIS program into both a DXF file(s), and an Excel spreadsheet. Then, import the DXF file into TNM and convert each TNM Object to its appropriate feature. Finally, cut/paste point names from corresponding excel sheet.

    It may also be important not to paste overly precise numbers into coordinate cells. For example, avoid pasting 46.78 as a coordinate, since TNM allows only values to the nearest 0.1. You could actually use Excel's Round() function for this, rather than relying upon display rounding. TNM's limit on coordinate precision is built into its database structure. It is not just a display matter in TNM's spreadsheets.

  15. What is the difference between TNM "dialogs" and TNM "tables"?

    TNM input dialogs located in the Input menu accept all your text input. TNM tables provide input and result summaries for documentation and printout purposes only.

  16. Why can't I get to some of the buttons on the right side of a dialog?

    You will need to set your computer monitor's resolution to 1024 x 768 or greater, 16 bit colors or greater, and the smallest available font size. You can usually accomplish this in the computer's Control Panel, Display, Settings function.

  17. I entered data into the header area, but why doesn't it show up in the Plan view?

    Some items in the dialog header area are used to enter default information that you would like subsequently created objects to contain. For example, you might first input your desired values of roadway width and pavement type in the roadway dialog header area. Then, as you digitize subsequent roadways, those new roadways now contain the values you entered in the header.

  18. Is TNM version 2.5 compatible with previous versions?

    23 CFR 772.17 requires the use of FHWA TNM version 2.5 or any other model determined by the FHWA to be consistent with the methodology of the FHWA TNM version 2.5. There have been several versions of the FHWA TNM that have been superseded by version 2.5. However, the changes in the versions have resulted in minor changes in how the user would use the model, especially from versions 1.1 to 2.1. The use of the model should not be confused with the results of the model. Identical input into different versions of the FHWA TNM, especially version 2.5 to earlier versions, would result in some differences in calculated sound level results. This is due to some changes to the algorithms in version 2.5 and not how the user would use the model. Information on the differences between the versions can be found on the Release Notes, User's Guide Addendum and/or Validation Studies listed on the webpages for the individual versions of the FHWA TNM.

Updated: 1/31/2017
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