Orange County Branch Newsletter

September 2015

Branch News

Airport Boulevard Railroad Grade Separation, Thermal

By: Joe Gonzalez, P.E.

ASCE Orange County held its August lunch event at the Center Club in Costa Mesa.  We had a great presentation on the Airport Boulevard Railroad Grade Separation project in the Community of Thermal, which is currently under construction.

This $29.4 million Riverside County Transportation Department (RCTD) project began in September 2010 with the preparation of the PA&ED. The PS&E was completed prior to December 2013 and met the construction funding deadline.  Construction began on March 2014 and is scheduled for completion in early 2016. The project proposes to grade separate the current at-grade crossing of Airport Boulevard (Ave 56) with the Union Pacific Railroad (UPRR) tracks by raising the roadway over the railroad and constructing a four-lane bridge that will span over the railroad tracks and State Highway 111 (Grapefruit Blvd).   The proposed bridge cross section will accommodate two additional lanes for future traffic demand.

On Airport Boulevard, the project begins west of Polk Street and ends near the SR-86 eastbound ramps.  To maintain access to Airport Blvd from Grapefruit Blvd and the adjacent properties , Palm St is being  extended to the north from the intersection of Airport Blvd to intersect with Grapefruit Blvd.  The residential properties along the south side of Airport Blvd will be accessed by a new frontage road adjacent to the raised Airport Blvd.

We were fortunate to have John Ashlock, P.E. present on this project.  John served as the Deputy Project Manager during the planning and design phases and now serves as RCTD’s resident engineer for this project.

John is registered civil engineer who has worked for the County of Riverside Transportation Department since 2005.  John has worked at RCTD in the design, development review, capitol project development, and construction divisions.  John previously worked in land development at Ludwig Engineering in San Bernardino and AEI-CASC Engineering in Colton, California.  John graduated from California State Poly Technic University, Pomona, with a Bachelor’s degree in Civil Engineering.  He is a member of the San Bernardino/Riverside branch of ASCE.

John Ashlock, PE, Riverside County Transportation Department presents the Airport Boulevard Grade Separation Project to ASCE OC
The Airport Blvd Railroad Grade Separation project includes several challenges including utility relocations and soil conditions which are subject to subsidence.  The proposed structure is near existing buildings that can be impacted by the surcharge that is typical for bridge construction.  The bridge components include:
  • 2 Span
  • 441’ Long
  • Longest Span 227 ‘
  • 80’ Wide (2-3 Lanes)
  • 3 Column Middle Bent
  • Prestressed Superstructure
  • Driven 14 x 117 H-Pile foundations
  • Aesthetic treatments which included the Thermal  Design Guidelines

John noted that the Parsons design team made a recommendation to use light weight fill (LWF) to address the local settlement.  The LWF is a third of the weight of soil and will reduce schedule since settlement period is 90 days for LWF in comparison to 9 months when using dirt.

Application of LWF for MSE walls

Application of LWF for bridge abutment and MSE walls

Placement of the LWF presented its challenges due to the hight temperature climate in the Community of Thermal.  The chalenges included:

  • Leveling pad elevation difference:  2’
  • Strap coverage: 6” min
  • 30” max lift
  • No longitudinal joints
  • Water supply fluctuations

The Airport Blvd Railroad Grade Separation project included unique aesthetic treatments that are consistent with Thermal Design Guidelines.  The components included:
  • Bridge soffit lettering & paint
  • Mountain motif
  • Superimposed acrobatic airplanes
  • Decorative wrought iron fence
  • Community logo panels
  • Mountain motif on abutment wall
  • Bridge soffit lettering

Simulation of the end

John also noted that there were a few structure challenges including:
  • Consolidation of concrete around prestressing ducts
  • Consolidation of concrete in bent cap
  • Consolidation of concrete around architectural letters
  • Size of stem & soffit pour ~ 2,000 yards
  • Expected Rock Pockets/Cold Joints

Girder Reinforcing Steel and Prestessing Duct Layout

Expected Rock Pockets

Addressing the rock pockets and cold joints took a collaborative effort with the design team and the contractor.  The remediation process included:

  1. Chip unsuitable material back to solid substrate
  2. Chip behind exposed steel to get “bite” around rebar
  3. Prestressing ducts get patched, sealed & mandreled
  4. Forms were constructed with “birds mouth” openings & sealed with expanding foam
  5. Mix & pour flowable concrete  patch
  6. Expected Cold Joints


A repair mortar that met the design compressive strengths per the specifications was used to make reparations. The project is moving along with a few more LWF lifts scheduled for the next few days. The end result will be a transportation project that will;
  • Eliminate train/automobile crossing conflicts
  • Improve vehicle and pedestrian safety
  • Reduce congestion and traffic delays
  • Improve emergency services responses
  • Facilitate regional commercial and commuter rail transportation
Gary Gilbert, PE GE, ASCE OC President, John Ashlock, PE, RCTD and Joe Gonzalez, PE, Programs Committee Chair

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