Coastal Rail Trails, Carlsbad, Oceanside, and Encinitas, CA
Coastal Rail Trails, Carlsbad, Oceanside, and Encinitas, CA


City of Carlsbad
City of Oceanside
City of Encinitas

Completion Date

2002 and 2005

DYA Client

Dokken Engineering, Inc.

Project Description

Diaz•Yourman & Associates (DYA) was the geotechnical subconsultant for three projects, consisting of 9.3 miles of Class I bike path through three cities. Much of the pathway alignment followed an existing railroad roadbed. In other areas, it was on existing roads. Because of environmental concerns, replacement of a 60-foot-long timber bridge was required along the Encinitas portion. This 3.7-mile-long trail also required a 230-foot, clear-span bridge, several new retaining walls (approximately 1,000 feet of retaining walls to 12 feet high), and a single 50-foot-long span concrete drainage crossing.

Project challenges included performing field investigations with limited access constraints. The key geotechnical concerns included expansive soils, collapsible soils, uncompacted fill, soft natural soils, liquefiable soils, slope stability, foundation support, foundation settlement, and pavement thickness. Geotechnical services included drilling borings, performing laboratory tests on soil samples, performing engineering analyses, and presenting the results in a written report. Recommendations provided addressed earthwork, shallow foundations, deep-driven pile foundations, lateral earth pressures, resistance to lateral loads, and flexible and rigid pavements and corrosion potential. The project included several bridges and retaining walls. DYA completed services within the project schedule and budget, resulting in a savings of 15 percent (compared to the initial project estimates) to the City of Encinitas.

Christopher M. Diaz, PE, GE – Geotechnical Manager

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

Gary K. Gilbert, PE, GE – Geotechnical Project Engineer

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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