Louis F. Cohn

A model for insertion loss degradation for parallel highway noise barriers

An algorithm is developed and validated for the prediction of the reduction, or degradation, of traffic noise barrier insertion loss when a second barrier is placed on the opposite side of the highway. The algorithm combines the basic emission, propagation, and barrier attenuation features of the Federal Highway Administration traffic noise prediction model with a geometrical acoustics approach for multiple reflections. The resultant model can accommodate any number of source lanes or receivers, three vehicle categories, and independently variable barrier heights and absorption coefficients. The model was validated against mathematical, scale model, and full scale field data received from other researchers, and has proved to be a good predictor of insertion loss degradation.

Seasonal Measurements of Aircraft Noise in a National Park

Jackson Hole Airport is the only air carrier airport located entirely in a National Park, that being Grand Teton. Concerns over noise impacts led to an Airport/Park agreement setting allowable levels, restricting flights and flight paths, and calling for compliance monitoring in the noise sensitive areas. This study documented seven days of continuous noise level measurements made at four sites in the Park during four consecutive seasons in 1985-86. Individual sound exposure level measurements at B-737/200 jets, Swearingen Metro turboprops, and general aviation aircraft permitted computation of “aircraft-only” day/night levels (DNL) at each site for each day. Measurement of half-hourly average sound levels permitted computation of “total” DNL for comparisons. Results showed general compliance with the DNL limits, except when winds necessitated northerly departures, in which case a single B- 737 could cause an exceedance. There were no statistically significant differences in mean aircraft DNL for each sit...

APPLICATION OF ADVANCED TECHNOLOGIES IN TRANSPORTATION: LESSONS LEARNED AND FUTURE DIRECTIONS

This panel session will address the current status of Intelligent Transportation Systems (ITS) and related programs, as well as experiences gained in the first decade of their deployment and will examine what lies ahead in terms of advanced technology applications in meeting ever increasing demand for mobility, security, and sustainability.

An Interactive Graphics Method for Use in Highway Air Quality Analysis

To avoid using coordinate bases models, VUPLOT, a set of independent Fortran computer programs which allow the analyst to access two main graphics subroutines, SCHEME and CONCEN, was developed. SCHEME plots coordinate input data for the model (CALINE3 or HIWAY-2) in plan view utilizing either a standard, complete input file, or files containing only lists of roadway link data and receptor data. CONCEN plots a plan view of a series of roadway links showing CO contribution by individual link at a selected receptor. VUPLOT also includes the option to label roadway links or receptors, or both, on the plots. The process for using VUPLOT is summarized. The VUPLOT program efficiently and safely uses these models in an interactive computer graphics package which aids in managing the coordinate data. 5 references, 1 figure.

Effects of median barriers on highway noise levels

Median barriers are widely used on roadways in the United States. The main purpose of this paper was to evaluate a median barrier performance in reducing traffic noise using the latest FHWA Traffic Noise Model, TNM version 2.5. For this study, median barriers were modeled on three different roadway configurations—at grade, depressed, and elevated. The analysis results indicated that the range of insertion loss for a median barrier at grade was less than 1.5 dBA with a barrier height of 2.5 to 10 ft. The range of insertion loss for a median barrier on a depressed roadway (5, 10, and 20 ft below grade) was 0 to 2.8 dBA with a barrier height of 2.5 to 4.5 ft and insertion loss increased up to 4.3 dBA with a taller barrier height of 6 to 10 ft. On an elevated roadway (5, 10, and 20 ft above grade), the range of insertion loss for a median barrier was 0 to 1.7 dBA with a barrier height of 2.5 to 10 ft. Given the results of this research, it is reasonable to conclude that a standard median barrier would not pro...

Study for how to reduce highway noise levels using TNM

Median barriers are widely used on roadways in the US. The purpose of this paper was to evaluate a median barrier performance in reducing traffic noise using the Traffic Noise Model version 2.5. For this study, median barriers were modeled on three different roadway configurations at grade, depressed, and elevated. The analysis results indicated that the range of insertion loss for a median barrier at grade was less than 1.5 dBA with a barrier height of 2.5 ft to 10 ft. The range of insertion loss for a median barrier on a depressed roadway (5 ft, 10 ft, and 20 ft below grade) was 0 dBA to 2.8 dBA with a barrier height of 2.5 ft to 4.5 ft and insertion loss increased up to 4.3 dBA with a taller barrier height of 6 ft to 10 ft. On an elevated roadway (5 ft, 10 ft, and 20 ft above grade), the range of insertion loss for a median barrier was 0 dBA to 1.7dBA with a barrier height of 2.5 ft to 10 ft. Given the results of this research, it is reasonable to conclude that a standard median barrier would not provi...

A review on barrier diffraction theories and related insertion loss comparisons in highway noise models

This paper presents a review on diffraction theories for highway noise barriers. Insertion loss based on different diffraction theories was investigated with two highway noise models, STAMINA and TNM 2.5. STAMINA implements the Kurze and Anderson empirical diffraction formula while TNM 2.5 deploys a simplified MacDonald analytical model. Quantitative analysis indicates that from the perspective of diffraction theory, the average difference of insertion loss between TNM and STAMINA for a point source is about 3 dB(A). To improve the prediction accuracy of TNM, it is recommended that the MacDonald solution, but with real and image sources, should be deployed.

A comparison of differences in highway noise barrier design using TNM 2.5 and STAMINA

In April 2004, the FHWA TNM 2.5 was released; all state transportation agencies are required to use it for all Federal funded projects by FHWA. TNM 2.5 has been modified from the previous versions to update the noise energy back to the source, and therefore influence the predicted insertion loss and absolute noise levels. The study was designed to compare the noise barrier design by both TNM 2.5 and TNM 2.0, as well as STAMINA 2.0. All these models were used to design noise barriers on the I‐64 St. Louis, MO project with the length for the mainline of 11 mile.

HITEC EVALUATION OF U.S. GYPSUM SIGHT AND SOUND SCREEN

A program of laboratory and field-testing designed to evaluate the capabilities and limitations of the U.S. Gypsum Sight and Sound Screen (SSS) is described. The evaluation plan proposes a collaborative testing and evaluation effort to be conducted with volunteer state highway agencies, including a program of field demonstrations. This will occur after a new product evaluation protocol is completed and applied to the SSS system. The study is being conducted as part of Highway Innovative Technology Evaluation Center (HITEC) program of ASCEs Civil Engineering Research Foundation. This study highlights the HITEC evaluation process as it is applied to the SSS.