When CALTRANS decided to upgrade and expand the Highway57 and Highway 60 Interchange with a high occupancy vehicle (HOV) Lane in Diamond Bar, CA, they contracted with CC Myers Construction to perform the work. Myers subcontracted with Condon-Johnson & Associates (CJA) for the installation of the sixty-one drilled shafts for the structures.

The Challenge
Drilled shafts in diameters up to 3.35 meters were needed to depths of 33 meters. These were installed utilizing an AF-300 drill built by IMT and assisted by a Liebherr 1400 crane. All shafts were tremie poured and subsequently tested by the CALTRANS gamma-gamma non-destructive testing system. These activities had to be carefully coordinated with traffic flow through the interchange.

The Solution
The drilled shaft subcontract, worth $ 4.8 million was performed in two mobilizations. Close coordination with traffic control forces was necessary as the adjacent lanes of highway were constantly in use. Reinforcing steel cage lifts, of up to 100,000 kg, were staged in off peak hours to minimize the impact on the traveling public.

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