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.