Plastic panel and structures using the same

A barrier comprising:

• at least one panel comprising a hollow rotationally molded plastic wall panel for forming part of a sound attenuation barrier, the hollow rotationally molded plastic wall panel having a length greater than a width, a thickness less than the width, a front wall, an opposite back wall and opposed first and second long edge regions, wherein the hollow rotationally molded plastic wall panel comprises a first end and a longitudinally opposite second end, wherein the first long edge region defines a first recessed portion to longitudinally receive and mate with a first longitudinal support structure and wherein the second long edge region defines a second recessed portion to longitudinally receive and mate with a second longitudinal support structure, wherein the first and second recessed portions of the hollow rotationally molded plastic wall panel are generally longitudinally extending;
• wherein the hollow rotationally molded plastic wall panel comprises a plurality of bridging portions to each form a material bridge between the front wall and the back wall, the plurality of bridging portions being integrally formed with the front wall and the back wall, and the plurality of bridging portions being disposed along the length at spaced positions inward of the first end and the second end;
• a vertically extending support structure that is fixed relative to a ground;
• and
• the first and second longitudinal support structures coupled to the vertically extending support structure;
• wherein the first and second longitudinal support structures are respectively received in the first recessed portion and the second recessed portion so that the hollow rotationally molded plastic wall panel is supported by the first and second support structures,
• wherein a first beam of the first and second longitudinal support structures is fixedly connected to the vertically extending support structure at a lowest beam position and at least a second beam of the first and second longitudinal support structures is fixedly connected to the vertically extending support structure at a position vertically spaced above the lowest beam position to secure the hollow rotationally molded plastic wall panel between the first beam and the second beam.