Traffic Noise Model
FHWA Traffic Noise Model Version 2.5
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.
The FHWA 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 the FHWA TNM.
The following documents are all documents that are associated with the FHWA TNM Version 2.5:
- FHWA Traffic Noise Model 2.5:
- Technical Manual:
- User's Guide:
- This addendum is to the FHWA Traffic Noise Model (FHWA TNM®) User's Guide, January 1998, and documents all the changes to the FHWA TNM GUI and operation since the FHWA TNM 1.0 release. The FHWA TNM® User's Guide (Version 2.5 Addendum), April 2004 (HTML) or (PDF - 1.4Mb).
- The original FHWA Traffic Noise Model (FHWA TNM® 1.0 release) Users's Guide, January 1998 (HTML) or (PDF - 3.9Mb)
- Preview of Validation of FHWA's TNM® (TNM): Phase I (TNM Version 2.5 Addendum, April 2004).(HTML) or (PDF 186Kb).
- TNM Version 2.5 Addendum to Validation of FHWA's TNM® (TNM) Phase 1 report, July 2004 (HTML) or (PDF - 944Kb).
The preview and addendum are intended to be used in conjunction with the Validation of FHWA's TNM® (TNM) Phase I Report, August, 2002 (HTML) or (PDF - 6.5Mb) to illustrate the all the validation efforts associated with the FHWA TNM.
- Compatibility 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 There have been several versions of the FHWA TNM that have been superseded by version 2.5.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.