During the past four decades, extensive research has been carried out on different noise barrier shapes using analytical and physical modelling as well as full scale testing. This paper reviews traffic noise barrier research and its findings to date. It provides a catalogue of noise barrier profiles; identifying the relative acoustic benefits of each and the physical principles on which they operate. The likely effects of ground and atmospheric conditions on their absolute acoustic performance are described. The types of barriers which are commonly used in practice and those deserving further attention are highlighted. Based on the findings of previous work, recommendations are made on possible areas of further research.

This paper investigates the use of periodically spaced edges or wells for the control of road traffic noise. The wells have uniform height and width and are placed on the ground. Physical scale modeling is used to assess the acoustic performance of these structures under laboratory conditions. It is shown that, in certain situations where the use of conventional barriers would not be appropriate, strategically designed riblike structures can provide insertion losses of typically 10-15 dB. The findings are explained in terms of acoustic scattering with the approaches used in the study of resonators and diffraction/interference gratings.