Work started June 15 on a $55.7 million project to upgrade the 77-year-old Wailua River Bridge on the island of Kauai for the Hawaii Dept. of Transportation (HDOT).

Scope of work includes the demolition of the existing seven bridge piers and associated timber piles and installation of 14 new 6 foot-dia., reinforced concrete drilled shafts, which will better stand up to the scouring of heavy rains and flooding.

The aging overpass, along with the neighboring Wailua Plantation Bridge, carry vehicles on the Kuhio Highway across the Wailua River and are the only connections for many communities north of the Wailua River to essential services in the city of Lihue, such as Wilcox Hospital, Lihue Airport and Nawiliwili Harbor, as well as major commercial and employment areas.

Over the last several years, the bridge has been susceptible to major flooding, most notably in April 2018 and March 2020. During these flood events, large piles of debris accumulated against bridge piers on the mountain side of the structure, forcing water down below the debris, causing major scouring of the bridge below the piers.

This project will increase the resilience of the route to future scour events, preserving critical access to services for the multiple communities mentioned above, says Randall Haraguchi, construction engineer, HDOT.

Kiewit Infrastructure West Co. is the general contractor; the designer of record is KSF Inc., working in conjunction with WSP and Geolabs; and the construction management team is led by Bowers+Kubota.

Originally built in 1945, the 424-foot-long Wailua River Bridge is supported by seven concrete piers, which are in turn supported by timber piles. As a scour repair project, the focus will be on the replacement of bridge piers and shafts. The bridge deck and railings, where most of the historic characteristics of the bridge are located, will be protected in place and only undergo relatively minor repairs such as addressing concrete spalls.  

The 14 new drilled shafts will be located on either side of the existing bridge piers. The contractor will be installing temporary construction platforms to stage their drill rig to install the drilled shafts at these locations to minimize impacts to the public, Haraguchi says.

There are no alternate routes around the Wailua River, so the contractor must keep the bridge open for the majority of time for the duration of the project, says Haraguchi.   

“Construction will occur from temporary platforms constructed across the river mauka [mountainside] and makai [oceanside] of the bridge,” he says. “At each pier, the contractor will temporarily jack up the bridge approximately 0.5 in. in order to demolish the existing pier and construct the new pier. The bridge will then be lowered to the new pier and the contractor will move to the next pier location.”

Additionally, as the temporary construction access encroaches onto State Parks property, occupancy of any one location on that property is limited to 180 days, Haraguchi adds. “The contractor has developed a tight schedule and will be using multiple crews to meet that requirement,” he says.

The project is scheduled to complete in November 2024. A total of $44.6 million in funding will come from the federal government, and $11.17 million from the state.