Interstate Route H-1 PM Contraflow, Phase 2

Pearl City Viaduct, which was constructed in the late 1960s, is an integral component of the H-1 Freeway.  This structure is approximately one mile long and consists of cast-in-place deck, precast girders, and cast-in-place bents.  The viaduct is supported by a combination of pile foundations and spread footings. 

In order to increase the vehicular capacity of this route, the existing outbound structure of Pearl City Viaduct was widened by 7.5 feet.   KSF, Inc. (KSF) designed the widening and performed the seismic evaluation of the outbound structure in accordance with the Hawaii Department of Transportation (HDOT) document dated October 20, 2010 with the subject title “Design Criteria for Bridges and Structures.”

The widening of Pearl City Viaduct involved extending the existing bent caps, installing precast girders, and casting the additional concrete deck. Precast members were utilized to extend the 61 existing bent caps.  This innovative method allowed the contractor to construct these precast bent cap extensions in a controlled environment for a better quality product.  In addition, casting these members concurrently with other work decreased the construction duration.  Precasting also permitted the contractor to minimize the footprint of disturbance under the viaduct.

Widening of the existing viaduct without adding new foundations required extensive analyses.  The existing structure with the new addition was three dimensionally modeled with the finite element analysis program, MIDAS.  KSF performed response spectrum and non-linear push over analyses.  The higher order analyses allowed for greater refinement of structure assessment which resulted in significant construction cost savings.  After evaluating the existing condition of the structure and strength of components, the existing foundation was found to be sufficient to carry the new loads.  In order to address deficiencies in the structure, a carbon fiber reinforced polymer composite system was utilized to strengthen specific bridge components.

Another key component of this project was to demonstrate the feasibility of rapid concrete pavement replacement with precast pavement panels.  A portion of deteriorated existing pavement near the Pearl City Viaduct was selected for this demonstration.  KSF designed the 86 precast concrete pavement panels for the 72-ft x 168-ft area on the H-1 Freeway.  The latest innovations in precast pavement panels, such as lifting and leveling devices, dowel insertion systems, and latex grout were incorporated.  This construction was successfully completed with minimal disruption to vehicular traffic.