Bids for Nānue Bridge rehabilitation project tens of millions higher than state’s revised cost estimate

The Hawai‘i Department of Transportation is reviewing three bids it received for a project to rehabilitate the more than 70-year-old Nānue Bridge outside of Hilo, and all are tens of millions more than the state’s latest revised cost estimate.

The project, which has been in the works since 2021, originally was estimated to be priced at $43 million. That estimate was revised in September to $88.4 million, according to Russell Pang, spokesperson for the state transportation department.

And now the estimated cost of the Nānue Bridge Rehabilitation Project is between $75 million and $100 million, according to the state highway division’s proposal contract and bond document.

But of the bids received for the project — from Nan, Inc., Kiewit Infrastructure West Co. and Hawaiian Dredging Construction Company — the lowest came in at $167 million, Pang said.

“The submitted bid amounts reflect what each bidder estimates it will cost to complete the scope of work detailed in the solicitation,” Pang said.

It is not clear why the bidders all came in more than $67 million higher than the state’s highest estimate. But Pang said the solicitations for bids closed on Feb. 6, and they are now being reviewed with the state expecting to award a contract by the end of March for an estimated project start in May.

While it is unclear why the bid came in higher than the estimated cost by the state, Pang said the agency will not have to rebid the project.

The Nānue steel trestle bridge at mile marker 18.5 along Hawaiʻi Belt Road is an important route between the east and west sides of the Big Island. The state has been making repairs to it for years, along with several other steel trestle bridges, including the Kolekole Stream Bridge Hakalau Stream Bridge.

The rehabilitation of the Nānue and Hakalau Stream bridges are a priority for the department of transportation because the only alternative route between the east and west sides of the island would be a more than 200-mile detour.

“Ensuring our roads and bridges are accessible and resilient for the communities that depend on them is vital to the quality of life in Hawaiʻi,” said Ed Sniffen, director of the Hawaiʻi Department of Transportation.

In January 2024, the state was awarded $74.6 million in competitive federal grant funds for the rehabilitation of the Nānue Bridge and Hakalau Stream Bridge, also located on Hawai‘i Belt Road between Honoka‘a and Hilo. The total estimated cost of the rehabilitation of both projects at that time was $124 million.

“This grant award will cover roughly two-thirds of the cost of the permanent repairs needed for these bridges along the Hāmākua Coast,” Sniffen said at the time.

But that no longer will be the case.

Work on the Hakalau Stream Bridge was awarded to Isemoto Contracting Co. and began in November, with an expected completion date of this November and estimated cost of $81 million.

For the Nānue Bridge project, the main goals are to rehabilitate the deteriorating substructure to allow for continued unrestricted use and to upgrade the railing to meet current safety standards. The bridge will not be widened and the traffic capacity will not increase, according to information in the 746-page Draft Environmental Assessment.

In June 2024, the state reviewed the draft environmental assessment, which determined there was no significant environmental impacts.

The bridge originally was built for trains in 1912 and was converted for use by vehicles in 1952. The structure is 531 feet long, with a roadway width of 28 feet. It is built at a deck elevation of 286 feet over Nānue Stream, making it the tallest bridge on the Big Island.

The substructure is composed of circa 1912 steel railroad trestle supports with masonry (lava-rock) abutments, according to the Historic Hawai’i Foundation.

The work will address repairing the corroded steel trusses, concrete deck, bridge railings and column pedestals. It also will address deficiencies in the bridge foundation. And, it will include cleaning and painting.

The project area is approximately 100 feet wide by 1,200 feet long along the roadway in the State Right of Way, and 300 feet by 1,000 feet makai of the highway.

The federal grant award is through the U.S. Department of Transportation Infrastructure for Rebuilding America program, which is a competitive funding opportunity for states, local government, and other agencies with transportation or land management responsibilities.

According to Pang, the project is being funded by an 80-20 split of federal (including the discretionary grant received last year) and state funds.