The UPRR rail yard, originally constructed in the late 19th Century to service intercontinental traffic, consists of approximately 140 acres of track and pavement areas adjacent to the Los Angeles River.  The yard modernization includes a quarter-mile-long retaining wall, new tracks, crane pads, truck-drive lanes, parking lots, and maintenance and crew facilities.

Shannon & Wilson explored subsurface conditions at the site to identify variations in the subsurface conditions that could affect the design of various structures over different areas of the site.  To support explorations, historical aerial photos from 1928 to the present were examined to distinctly identify portions of the yard underlain by natural soils versus fill soils. Environmental testing for potential chemical by-products in existing soils at the site was completed to assist in soil disposal and provide recommendations with respect to environmental conditions during construction. Multiple retaining wall options were provided to support a ¼ mile long, 20-foot vertical cut along the southern portion of the yard adjacent to Mission Road.  Recommendations for an anchored solider pile wall, soil nail wall, counterfort wall, and temporary cut and cantilevered wall were included, as well as recommendations for a new yard and lead track, including rail type, tie spacing, ballast and sub-ballast sections, and construction considerations using both AREMA and Union Pacific guidelines.