East-West Connector, Fremont & Union City, Alameda County, CA

PARIKH provided geotechnical engineering services for the project, which connects Interstate I-880 at Decoto Road to Mission Boulevard, in Union City. This project has multiple segments, requiring construction of six new bridge structures. PARIKH conducted field investigation and provided recommendations for pavement design, bridge foundations, and retaining walls. Sections included saturated and soft soils, liquefiable subsurface conditions, and dense sand pockets which required consideration and mitigation measures.

Segment A entails widening sections of Decoto Road, Fremont Boulevard, and Paseo Padre Parkway. PARIKH provided recommendations for pavement design with pavement reinforcing fabric for overlay and for two retaining walls along the roadway widening with foundation subgrade improvements and soundwall design.

Segment B constructs new roadway from Paseo Padre Parkway to Alvarado-Niles Road, with three new bridge structures across Alameda Creek Flood Control Channel and Old Alameda Creek. New bridge structures are supported on driven open-end steel pipe piles. PARIKH provided pavement design recommendations and foundation recommendations for the bridge structures and retaining walls. Subsurface conditions include high liquefaction potential. PARIKH’s recommendations included liquefaction mitigation measures for the pile foundations, hydraulic scour depth considerations, and ground improvements at the abutments using Rammed Aggregate Piers (RAP).

Segment C constructs a new depressed roadway from Alvarado-Niles Road to Mission Blvd., with three new bridge structures at existing railway tracks (part of the BART and Union Pacific Railroad (UPRR) networks.) Roadway plans use topography of an existing retention pond to reduce the total amount of required cuts and excavation. Connector roadway plans include multiple retaining walls lengthwise and deep soil-cement mix (DSM) cutoff walls for groundwater control and dewatering. New bridge structure designs are supported on open-end driven steel pipe piles, with recommendations for an indicator pile program and pile load tests per BART structural requirements.

PARIKH provided recommendations for retaining wall lateral earth pressure and design, DSM wall design, and construction and pavement design using geotextile enhancement to improve subgrade conditions. PARIKH completed all work on schedule and within budget.