In order to alleviate the daily afternoon congestion and to meet Federal standards, the Hawai’i Department of Transportation (HDOT) widened the westbound lanes of Interstate Route H-1 from Kaonohi Street to the Pearl City Off-Ramp.

Widening of the Interstate Route H-1 was accomplished by installing 5,100 feet of soil retaining structures and adding approximately 30 feet to the westbound width of the 1,245- foot long Waimalu Viaduct.  This brought the existing highway into compliance with Federal standards by providing a total of two 12-foot shoulders and six 12-foot travelways.

The widening of the Waimalu Viaduct was designed to not only support itself but to brace the existing structure during a seismic event.  This was achieved by making the new widening stiffer and stronger with a higher level of ductility.  The new widening, which consists of precast girders and a cast-in-place deck, was constructed independent of the existing bridge and then connected with the existing structure.  In order to minimize traffic disruptions during the connecting concrete closure pour construction, an accelerator/corrosion inhibitor was utilized to enable the concrete to reach final set in 3-hours.  This allowed the travel lane directly adjacent to the closure pour to be opened approximately 3-hours after the concrete has been placed.

KSF, Inc. conducted the seismic analysis of Waimalu Viaduct and provided the designs of the bridge widening and retaining structures.  In addition, we intimately worked with HDOT to swiftly resolve issues that arose due to unexpected conditions discovered during construction and to verify that the contractor’s work conformed with all project documents.