Embodiments relate to a plastic wall panel, comprising a hollow body having external walls and defining an internal cavity. The external walls include: a first major side wall, a second major side wall opposite the first major side wall, a minor top wall, a minor bottom wall, a first minor end wall and a second minor end wall opposite the first minor end wall. The minor top wall and the minor bottom wall each define mating structure to mate and align with another adjacent panel so that multiple panels can be tiled together to form at least part of a sound attenuation barrier. The hollow body defines a passage extending between the first and second major side walls and through the first and second minor end walls to receive a reinforcing beam.