disclosed herein are embodiments of a roadside barrier segment to sit on top of a retaining wall to provide impact resistance to vehicular traffic . concrete traffic barriers are pre - cast in a controlled manufacturing environment then transported as a modular precast concrete segment to the jobsite and installed interlocking directly on top of an earth retaining wall . the precast concrete segment is designed to have a counterweight from soil backfill on a stem of the precast segment that resists overturning pressures from vehicle impact on the traffic barrier segment that extends above the roadway surface . the stem may be triangular in shape to capture more of the backfill soil . a vertical node may be placed on one side of the segment and a receiving channel on the opposite side of the segment to allow the interaction of adjacent segments to share impact loads from motor vehicles .