ACE San Gabriel Trench Grade Separation, San Gabriel, CA
ACE San Gabriel Trench Grade Separation, San Gabriel, CA


Alameda Corridor East Construction Authority

Completion Date


DYA Client

Moffatt & Nichol

Project Description

The project was for design and engineering services for the grade separation of four streets over the Union Pacific rail line (Alhambra subdivision) in the City of San Gabriel. The grade separations will be undercrossing the existing railroad tracks within the Union Pacific Railroad (UPRR) right-of-way and constructing bridges over the tracks at Ramona Street, Mission Road, Del Mar Avenue, and San Gabriel Boulevard. Project limits extend from just east of the Chapel Avenue Bridge on the west to Walnut Grove Avenue in the City of Rosemead. Project elements included utilities, geotechnical, structures, and drainage design.

Diaz•Yourman & Associates’ (DYA) tasks included:

Preliminary engineering geotechnical investigation plan for borings, observation well construction and monitoring, and laboratory analysis for all facilities, including the UPRR right-of-way, drainage wash locations, and roadway crossings.

Concept-level geotechnical guideline report based on existing data to support the advanced engineering concept plan and preparation of a memorandum discussing geotechnical and hazardous materials issues and potential alternative solutions, such as wall and foundation types.

Preliminary engineering for geotechnical and environmental investigations and testing. Reports providing geotechnical engineering design parameters and construction considerations.

Preliminary and final geotechnical design report, which provides preliminary conclusions and recommendations regarding geotechnical issues, types, and design criteria for walls and structure foundations and construction considerations.

V. R. (Nadesh) Nadeswaran, PE, GE – Geotechnical Manager

Allen M. Yourman, Jr., PE, GE – Geotechnical Principal

Our Services


  • Site and route evaluations
  • Geologic hazards
  • Seismic design
  • Site characterization
  • Subsurface drainage
  • Grading
  • Ground improvement
  • Slope stability
  • Foundations
  • Dynamic analyses
  • Pavements
  • Instrumentation


  • Material sources
  • Construction observation and testing
  • Verification of anticipated conditions
  • Evaluation of changed conditions
  • Foundation installation
  • Instrumentation
  • Claims evaluation


  • Site characterization
  • Remediation
  • Solid and liquid waste disposal
  • Landfill
  • Aerially Deposited Lead (ADL) Studies
  • Phase I Initial Site Assessments (ISA)
  • Phase II Hazardous Waste Studies
  • Sustainability


  • Forensic investigation
  • Litigation support

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