The Avenue S Corridor Improvement Project comprised the replacement of a two lane bridge on Avenue S over the Union Pacific Railroad tracks with two new bridges totaling six lanes. The realignment of 20th Street East and improvements to Avenue S from the new bridge to the Antelope Valley Freeway (Highway 14) approximately 1.5 miles west of the project area were part of the project development.The new bridges consist of cast-in-place, post-tensioned, concrete box girders supported on embankment abutments on the ends with a pair of intermediate bent pier walls. Pier/pile foundations support the abutments and bents. Earth Systems performed a geotechnical engineering investigation which addressed surface and subsurface soil/bedrock conditions, groundwater, regional geology, site geologic conditions, and geologic hazards. Recommendations provided included seismic design parameters, slope stability, site preparation, utility trenches, conventional foundation design, drilled pier foundations, pier construction and installation, retaining wall design, and pavement sections. During construction of the infrastructure improvements, Earth Systems team of certified technicians performed compaction testing of the bridge approach embankment and Avenue S/20th Street East street improvements, along with special inspection and materials testing of the bridge construction operations.