Design Of Noise Barriers Research Articles

A comparative study of highway noise barrier design using two different computer models

Studies indicate that more people are exposed to noise from motor vehicles than any other source of noise. For this reason, the adverse noise impact of highway noise is of great concern to land use planners, regulatory agencies, and affected communities. To assess the impacts of new highway projects and to identify the effectiveness of mitigation measures, the federal government and some states require that noise analyses be conducted using specific computer models. STAMINA/OPTIMA is the Federal Highway Administration's approved model and is used by many states. SOUND 32 is the California Department of Transportation's preferred model, and is used for highway projects in California. Both models are based on similar mathematical formulations, but differ in vehicle noise emission characteristics, height of noise sources, and attenuation effectiveness for noise walls and earth berms. The purpose of this paper is to report the results of a comparative noise analysis in which both models were applied to an actual highway segment. The influence of traffic volumes, speeds, highway geometry, grade, and receptor distance on the model's estimated noise levels was studied. Differences in the location, dimensions, and effectiveness of barriers recommended by the two models are identified and some of the merits and drawbacks of the models are briefly discussed.

Model studies of barrier performance in the presence of ground surfaces. Part II—Different shapes

Modeling experiments are reported which have investigated the frequency dependence of barrier insertion loss for various noise barrier designs. The effect of ground surfaces has been studied, treating both grass-covered ground and asphalt. Results show that interference effects are an important feature of observed behavior. Use is made of this knowledge in the design and testing of new barrier designs, which deliberately introduce a beneficial destructive interference phenomenon to increase insertion losses over well-defined ranges of frequency.

Aircraft cabin noise barrier design and test

The cockpit and cabin of contemporary propeller driven lightplanes continue to suffer high ambient noise levels in flight. These noise levels are typically 85–95 dBA. It was sought to typify and test lightweight barrier configurations in an attempt to achieve the 30 dB predicted performance [J. T. Howlett and D. A. Morales, J. Acoust. Soc. Am. 59, S64 (A) (1976)]. Several structural arrangements were tested as 12 in. (30 cm) square samples. Broadband transmission loss values of 20–25 dB were easily achieved, as opposed to considerably smaller values for thin aluminum panels. The barrier performance due to stiffness over and above that due to the mass law is clearly evident at lower frequencies. The achievable TL values are compared with known aircraft noise spectra, both inside the outside the cabin, to predict cabin quieting achievable with practical weight and cost constraints.

A note on improving the attenuation given by a noise barrier

Some aspects of diffraction theory relevant to design and performance of noise barriers are described and a suggestion for improving attenuation provided by an acoustic screen is put forward.

Airports can be quieter

There will be a considerable increase in airport noise levels in the 70s because of a tremendous increase in air traffic and the introduction of jumbo jet and supersonic aircraft. Noise levels characteristic for these new aircraft are identified and practical solutions for airport noise suppression discussed. An analysis is made of using inexpensive model tests to optimise the design of airport noise barriers and to establish optimum design parameters for airport designers. New airports can be built to take full advantage of all possible methods for noise suppression by locating runways, buildings and sound barriers at various ground levels and preferred locations in order to obtain lowest possible noise levels.