Noise barriers with varying cross-section optimized by genetic algorithms

The efficiency of a noise barrier largely depends on its geometry. Besides the height of the barrier and its top element form, the cross-section of the barrier contributes to its performance as well. The Boundary Element Method is often used as the numerical tool for simulating the behavior of proposed barrier shapes, both in 2D and 3D spaces. This paper deals with the optimization of barrier cross-section, not only by taking into account its acoustical performance (sound insertion loss), but also considering the economic feasibility of using various materials and various shapes for building the barrier. Therefore, the economic feasibility coefficient is defined and used as a final numerical value for comparing the overall efficiency of barrier design. The optimization process is done by using a genetic algorithm. Five basic forms of barrier elements and five building materials were pre-defined and characterized for the optimization process. The number of candidate units in the starting population was varied in order to examine the influence of population size on the final results. Barrier performance was evaluated for a point sound source in a 3D simulation space, and both its total rating based on the economic feasibility coefficient and its acoustical performance itself were evaluated and compared to a reference concrete barrier of the same height.