Evaluation of Federal Highway Administration’s Traffic Noise Model for Pavements in Qatar

Modeling road traffic noise levels without including the effects of meteorology may lead to substantial errors. In the United States, the required model is the Traffic Noise Model which does not include meteorology effects caused by refraction. In response, the Transportation Research Board sponsored NCHRP 25-52, Meteorological Effects on Roadway Noise, to collect highway noise data under different meteorological conditions, document the meteorological effects on roadway noise propagation under different atmospheric conditions, develop best practices, and provide guidance on how to: (a) quantify meteorological effects on roadway noise propagation; and (b) explain those effects to the public. The completed project at 16 barrier and no-barrier measurement positions adjacent to Interstate 17 (I-17) in Phoenix, Arizona provided the database which has enabled substantial developments in modeling. This report provides more recent information on the model development that can be directly applied by the noise analyst to include meteorological effects from simple look-up tables to more precise use of statistical equations.

Download Full-text

A new steady-state traffic noise model for estimating L(h) on free flow roads using Reference Energy Mean Emission Levels

Building and Environment ◽

10.1016/j.buildenv.2021.107685 ◽

2021 ◽

pp. 107685

Author(s):

Sh Afandizadeh ◽

H. Gharehdaghli

Keyword(s):

Steady State ◽

Traffic Noise ◽

Free Flow ◽

Noise Model

Download Full-text

Traffic Noise Model vs. Extreme Topography

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1859-08 ◽

2003 ◽

Vol 1859 (1) ◽

pp. 65-71

Author(s):

Michael A. Staiano

Keyword(s):

Traffic Noise ◽

Severe Case ◽

Sound Attenuation ◽

Noise Model ◽

Interstate Highway ◽

Site Model ◽

Sound Levels

Traffic noise exposures were measured at various locations adjacent to an Interstate highway and compared with sound levels predicted by the FHWA Traffic Noise Model (TNM). The prediction procedure underestimated the measured sound attenuation by 6 to 12 A-weighted decibels. Various TNM site model configurations were evaluated in an effort to improve agreement between measurements and predictions. For the site tested—a severe case with relatively distant receptors and extreme topography—variations in ground impedance (including a median ground zone) had little benefit or were counterproductive, while adding topographic detail via terrain lines helped somewhat. The best agreement resulted from the incorporation of a tree zone for the wooded site. However, this benefit is thought to be chance, because the site was not only relatively lightly wooded but also thinly foliaged at the time of the on-site measurements.

Download Full-text

Comparison of Traffic Noise Model 2.5 with 2.1 and Measured Data

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198105194100119 ◽

2005 ◽

Vol 1941 (1) ◽

pp. 149-154

Author(s):

A. A. El-Aassar ◽

R. L. Wayson ◽

J. M. MacDonald

Keyword(s):

Traffic Noise ◽

Measured Data ◽

Noise Model ◽

Average Error ◽

Matched Pairs ◽

Federally Funded ◽

Reference Measurement ◽

Previous Version ◽

Ground Effects ◽

Predicted Values

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.

Download Full-text