Comparison of Traffic Noise Model 2.5 with 2.1 and Measured Data

Abstract

Traffic Noise Model Version 2.5 (TNM 2.5) will soon be the official traffic noise model required by the FHWA for federally funded projects. TNM was updated from Version 2.1 to 2.5 to address two major issues: the overprediction found in the previous version of TNM and an anomaly related to diffraction points. This research focused on comparing the TNM 2.5 predicted results with TNM 2.1 predicted values and with measured data from 18 barrier locations in Florida. Matched pairs of predicted and measured differences between the data for TNM 2.5 and TNM 2.1 were evaluated and a direct comparison of the two models was made. This research demonstrated that the predicted results from TNM 2.5 had an average error for all 18 barrier locations of less than 1 dB. However, when each of the sites is evaluated individually, TNM 2.5 has a tendency to underpredict slightly at many of the evaluated barrier locations. Finally, TNM 2.5-predicted results tend to be about 3 dB(A) on average less than TNM 2.1 at a defined reference measurement position, which is relatively unaffected by ground effects or diffraction, and about 1 dB less at microphone positions behind evaluated barriers when compared with TNM 2.1.

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References

Anderson

G. S.

, Lee

C. S. Y.

, Fleming

G. G.

, and Menge

C. W.

. FHWA Traffic Noise Model, User's Guide. FHWA-PD-96-09. FHWA, U.S. Department of Transportation, 1998.

Rochat

J. L.

, and Fleming

G. G.

. Validation of FHWA's Traffic Noise Model® (TNM): Phase 1. Report No. FHWA-EP-02-031 and DOT-VNTSC-FHWA-02-01. John A. Volpe National Transportation Systems Center, Acoustics Facility, Cambridge, Mass., 2002.

Rochat

J. L.

FHWA's Traffic Noise Model (TNM) Versions 2.4 Validation Results. Presented at National Conference and Exposition on Noise Control Engineering (Noise-CON 2004), Baltimore, Md., 2004.

Wayson

, MacDonald

, El-Aassar

, Lindeman

, and Berrios

. Florida Noise Barrier Evaluation and Computer Model Validation. In Transportation Research Record: Journal of the Transportation Research Board, No. 1859, Transportation Research Board of the National Academies, Washington, D.C., 2003, pp. 72–78.

Wayson

R. L.

, MacDonald

J. M.

, and El-Aassar

Continued Evaluation of Noise Barriers in Florida. FDOT Project No. BD-355-2. Florida Department of Transportation, Tallahassee, 2002.

Lee

C. S. Y.

, and Fleming

G. G.

. Measurement of Highway Related Noise. FHWA-PD-96-046. John A. Volpe National Transportation Center, FHWA, U.S. Department of Transportation, Cambridge, Mass., 1996.

Wayson

R. L.

, MacDonald

J. M.

, Arner

, Lindeman

W. M.

, and Berrios

. Comparison of Measured and Modeled Sound Levels in the Vicinity of Traffic Noise Barriers. In Transportation Research Record: Journal of the Transportation Research Board, No. 1792, Transportation Research Board of the National Academies, Washington, D.C., 2002, pp. 57–64.