The state Department of Transportation on Monday will begin work on the Hilo side of Daniel K. Inouye Highway that authorities hope will end a spate of crashes which have resulted in five fatalities this year — all within a period of less than a month.

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The state Department of Transportation on Monday will begin work on the Hilo side of Daniel K. Inouye Highway that authorities hope will end a spate of crashes which have resulted in five fatalities this year — all within a period of less than a month.

In an online meeting Friday that was required as part of DOT’s declaration of a traffic emergency zone on the highway between the 5.5- and 28-mile markers, engineer Clifford Corpuz said short-term measures to be taken include the installation of open-graded friction course in the areas between mile markers 6 and 19 where surface water ponds on the roadway.

Friction course is a highly porous asphalt mixture used as the surface layer on high-speed roadways that allows water to drain directly through the pavement into the underlying dense-graded layer — reducing the chances of motorists hydroplaning and losing control of their vehicle.

“It’ll take about a month to install,” said Corpuz, who estimated the cost of the paving will be about $15 million. “We’re going with state funds at the moment.”

The traffic emergency zone declaration — which the DOT announced Friday after a fiery fatal crash a day earlier on DKI Highway, also known as Saddle Road — allows DOT to accelerate procurement and permitting for additional engineering mitigation.

Corpuz said the open-graded friction course was installed about a decade ago in Kaawalii Gulch, the northernmost of three horseshoe gulches on Hawaii Belt Road between Hilo and Honokaa.

“So, we’re going to start more mauka, which is mile markers 16 to 19,” Corpuz said, adding that crews will then pave the more makai stretch. “The reason that we’re starting on mile marker 16 to 19 is because that’s where we have a higher rate of fatalities in that area.

“It’ll take approximately a month to get this open-graded friction course completed.”

Corpuz said after that’s completed, the road will be restriped between the 5.5- and 28-mile markers with a paint that provides greater visibility during inclement weather — which on DKI Highway can include dense fog as well as heavy rain.

In-lane thermoplastic rumble strips and additional “curve ahead” chevron signs will also be installed.

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DOT spokeswoman Shelly Kunishige said there will also be speed cameras installed on the highway as part of the short-term mitigation plan. Registered owners of vehicles detected by the cameras exceeding the posted speed limit by 11 mph or more will be sent a warning.

“As part of the speed camera installation, they’ll be doing a seven-day speed survey, so we can get more data, basically, on the speeds that people are currently going on the highway,” Kunishige said. “But I will note that some of our data has shown that people are going up to 109 mph on DKI Highway.”

DOT crews have conducted sight-distance studies, closed multiple passing zones between mile posts 8.3 to 27.25, posted electronic signs with safety messaging and recently installed thermoplastic curbs and flexible delineators between mile posts 16.7 and 19.

The department is also in the process of an engineering study for long-term improvements which could include a full divided highway conversion, installation of medians within the existing right of way, and/or alternate passing lanes.

“We’ll be getting a report, I guess, within four months on what potential long-term options we’ll be going with,” Corpuz said. Noting that turning the DKI into a full divided highway is “the most expensive option” being considered, he added, “We’re not yet set on which one, but we’re looking into them all.”

Aaron Stene of Kailua-Kona noted during the meeting the state is cutting a half-billion dollars from its Statewide Transportation Improvement Program, or STIP, over the next decade, from $3.2 billion to $2.7 billion.

“If the highway is widened, it will take funding from other projects. I’m concerned about this,” Stene said.

“Any large-scale project like this would need to go through the STIP process,” Kunishige replied.

According to Kunishige, the traffic zone emergency designation “may continue for a period of up to five years.”

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Email John Burnett at [email protected].