Abstract: A highway noise barrier panel assembly has a base panel, sound-attenuating insulation located adjacent an exterior surface of the base panel and an insulation retaining structure to secure the insulation in fixed relation to the base panel. A noise barrier has at least two generally vertical support posts, at least one wall panel with sides attached to the support posts, sound-attenuating insulation located adjacent an exterior surface of the wall panel and an insulation retaining structure to secure the insulation in fixed relation to the base panel.

Abstract: A rectilinear extruded plastic wall forming panel characterized being able to directly connect to next adjoining panels either by sliding adjoining panels together or by pushing them together. Also, if one of the panel walls is to become an exterior wall, it is preferably reinforced, for example with pultruded fiberglass or foamed PVC.