A system comprising: a precast roadway barrier segment ; a substantially level underlying earth retaining wall; and a leveling course situated below the precast roadway barrier segment and above the substantial level underlying earth retaining wall, the leveling course comprising at least one precast leveling segment , the at least one precast leveling segment comprising at least: a top surface parallel to a sloped roadway situated above the leveling course; a bottom surface parallel to a top precast segment of the substantially level underlying earth retaining wall situated below the leveling course; a horizontal stem extending outwardly from a rear surface of a front portion of the at least one precast leveling segment, wherein the horizontal stem extends from the top surface to the bottom surface, a lower portion of the horizontal stem comprising a triangular portion extending outwardly from a left side and a right side of the horizontal stem, and the triangular portion of the horizontal stem comprising two cavities disposed along a face of at least one side of the triangular portion; and an alignment seat extending along at least a portion of the horizontal stem, wherein the substantially level underlying earth retaining wall is nonparallel to the sloped roadway. a precast roadway barrier segment ; a substantially level underlying earth retaining wall; and a leveling course situated below the precast roadway barrier segment and above the substantial level underlying earth retaining wall, the leveling course comprising at least one precast leveling segment , the at least one precast leveling segment comprising at least: a top surface parallel to a sloped roadway situated above the leveling course; a bottom surface parallel to a top precast segment of the substantially level underlying earth retaining wall situated below the leveling course; a horizontal stem extending outwardly from a rear surface of a front portion of the at least one precast leveling segment, wherein the horizontal stem extends from the top surface to the bottom surface, a lower portion of the horizontal stem comprising a triangular portion extending outwardly from a left side and a right side of the horizontal stem, and the triangular portion of the horizontal stem comprising two cavities disposed along a face of at least one side of the triangular portion; and an alignment seat extending along at least a portion of the horizontal stem, wherein the substantially level underlying earth retaining wall is nonparallel to the sloped roadway. a top surface parallel to a sloped roadway situated above the leveling course; a bottom surface parallel to a top precast segment of the substantially level underlying earth retaining wall situated below the leveling course; a horizontal stem extending outwardly from a rear surface of a front portion of the at least one precast leveling segment, wherein the horizontal stem extends from the top surface to the bottom surface, a lower portion of the horizontal stem comprising a triangular portion extending outwardly from a left side and a right side of the horizontal stem, and the triangular portion of the horizontal stem comprising two cavities disposed along a face of at least one side of the triangular portion; and an alignment seat extending along at least a portion of the horizontal stem, wherein the substantially level underlying earth retaining wall is nonparallel to the sloped roadway. <EOS>