I-15 / Base Line Avenue Interchange

The Project.

Improvements to a major interchange have a positive impact on traffic, safety and often the area economy. The Base Line Road Interchange improvements resulted in all of these. Traversing Rancho Cucamonga into Fontana, access to and from I-15 has seen significant increases in traffic congestion. The completed improvements realigned and widened both south and northbound diamond ramps, and added a southbound loop on-ramp, and acceleration and deceleration lanes on I-15. Base Line Road and East Ave both increased capacity by two additional lanes.




San Bernardino County Transportation Authority


Rancho Cucamonga, CA


  • Source Inspection
  • Geotechnical Testing

Project Fact:

Leighton was responsible for testing, documenting, and reporting on more than 1,000 items on this project.

The Leighton Solution.

Leighton was part of the Construction Management team, providing quality assurance geotechnical and materials testing, and source inspection. Prior to any testing, we provided a constructability analysis by reviewing existing geotechnical reports, plans and specifications.

As the Structural Materials Representative, Leighton assisted the construction management team in preparing the QA/QC plan for the project and reviewing the contractor’s QA/QC plan. Leighton was also responsible for the Caltrans approved Source Inspection Quality Management Plan, tracking any updates, and submitting monthly SMR reports.

Geotechnical observation of backfill placement, foundation excavations, and HMA was documented and reported by Leighton’s Caltrans approved technicians. Concrete sampling at site and batch plant testing was also under Caltrans oversight in the field and in our laboratory. All materials manufactured or fabricated away from the jobsite required sampling and testing, such as concrete MSE panels, prestressed concrete piles, prestressed concrete girders, Prestressed concrete box girders. Leighton’s SMR coordinated inspections, and assisted with materials engineering issues and submittal reviews.

This project design included precast, prestressed, concrete wide flange girders. Inspection for girders included verify rebar placement, verify prestressing strands (packs/coils), verify prestressing at manufacture site, strand layout, concrete slump and break in lab, then final site inspection and tag if approved.