The eventual replacement of an aging Hilo bridge will come with improvements to a nearby problematic intersection.
The Four Mile Creek Bridge, located at the south end of Kilauea Avenue, was originally built in 1916 but carries roughly 11,000 vehicles per day thanks to its location directly connecting Kilauea Avenue with Highway 11. But with the bridge only wide enough for a single lane, it frequently snarls traffic as drivers wait for their turn to cross.
In order to alleviate congestion in the area, the Hawaii County Department of Public Works is developing a plan to replace the bridge with a wider one. At the same time, the nearby intersection of Kilauea Avenue and Haihai Street will be modified to allow for safer and easier turns onto and off both roads.
At a community meeting Thursday night, engineer Ikaika Kincaid explained that the current Four Mile Creek Bridge is about 20 feet wide, but will be expanded to about 60 feet. Not only will this expansion allow for two lanes of traffic, but it will also include room for sidewalks and bike lanes on both sides of the street.
As for the historic original bridge, it will be demolished, but aspects of it will be retained for its replacement, Kincaid said.
“We still have to consult with the State Historic Preservation Department about it, but we’ll have to mitigate the removal of a historic site,” Kincaid said. “It turns out that the bridge’s most significant feature is its guardrails, so we’ll try to incorporate their design into the new bridge.”
Kincaid said the new bridge guardrails will be tested against collisions and will meet federal height standards, unlike the historic guardrails.
During construction, Kincaid said the bridge should remain open to commuters.
The original bridge will remain standing until one half of the replacement is built. At that point, the traffic pattern will be switched so that drivers traverse the half-bridge. Then the original bridge will be demolished, and on its site the second half will be built.
Kincaid said the bridge will ideally remain about 100 feet long with a single span.
Meanwhile, initial designs for the modifications to the Kilauea/Haihai intersection include a traffic signal and a new left-turn lane on northbound Kilauea.
DPW Engineering Division Chief Keone Thompson said the department has considered a roundabout for the intersection, but the terrain makes such an option unfeasible unless the county purchases an adjacent lot.
DPW Director Steven Pause added a roundabout would require additional measures to control traffic speed.
But the designs for the intersection and bridge are not finalized. At the meeting, several attendees made suggestions — Hilo Rep. Richard Onishi asked whether the bridge really needs two sidewalks and bike lanes — that Thompson and Pause said they would take under advisement.
The total project cost is estimated to be $14.5 million. Onishi said he has secured $12 million from the state, with a $6 million match from the county, which more than covers the cost, although Pause noted that the final cost will, as always, depend on the contractors and the cost of materials at the time of construction.
That time is still far off, though.
Pause said the project will require an environmental assessment, which should be completed along with other permitting in two years. Assuming all goes well, Pause said the project could go out to bid by the fall of 2025 and be completed in about 18 months, with a tentative completion date in April 2027.
Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.