Characterization of Traffic Noise in Open Areas  

Project Title: Characterization of Traffic Noise in Open Areas

Applicant: The Hong Kong University of Science and Technology

Total Approved Grant: $253,300

Duration: 01/07/96 to 31/12/97

Project Status/Remarks: Completed

Scope: To study the noise emitted from vehicles in open areas and to develop a method to predict the impact of traffic noise on residents living on high-rise buildings.

Summary of the Findings/Outcomes: Vehicles were by far the greatest contributors to the high noise level in Hong Kong. Their share of the total acoustical energy was in fact so large that they alone could count for the steady or slowly varying ambient noise level. The number of vehicles was large and noise from vehicles could be treated statistically. In this project, vehicles were categorized as : private cars, light vehicles, public buses, heavy vehicles and articulated heavy vehicles. Noise levels were measured simultaneously at seven locations (from the ground level to the sixth floor) in a building. Each measurement point was at a position 1 m from the exterior of the building facade. The octave-band spectra at these locations indicated that vehicles should not be treated as omnidirectional sources. Most vehicles would emit noise more effectively at large elevation angles. The main characteristics of the spectra were peaks at the 63-Hz band. The sound level of the average vehicle of a given category normally increased with size/weight. It was found that heavy vehicles (articulated), heavy vehicles and public buses were the dominant sources of noises at the measurement site (and major roads in Hong Kong).

Detailed spectral information on noise levels at various floors of a building could be obtained by incorporating the results of this project into the calculation of road traffic noise. Environmental engineers, consultants, architects and developers could make use of the spectral information to predict the impact of traffic noise on residents and come up with novel building designs.