They are among a total of 13 people killed while traveling on the road in the past seven years, according to published reports.

And data collected by the Honolulu Police Department show 23 major collisions on the road during the one-year period that ended Aug. 30, 2004. Major collisions are those that result in death or critical injury, or property damage of more than $3,000.

Meanwhile, a study released yesterday by a nonprofit group in Washington, D.C., shows the death rate for motorists on rural roads during 2003 was more than 2ý times the rate for driving on all other roads.

Lt. Bennett Martin, of HPD's vehicular homicide unit, is well aware of the Kunia Road's deadly history.

"Without even looking at the stats, I can tell you it's right up there," Martin said. "It may not be quite as bad as the worst of the worst, but it comes close."

Veteran traffic fatality investigators said several factors make Kunia Road far deadlier than it appears:

• It is a "back-road alternative" that connects the population and job centers of Wahiawa and Waipahu, and people who travel the road are often in a hurry to get from one town to the other. Police believe the 1991 Chevy Cavalier carrying Nestor Manzano Sr., 43, and sons Nestor Jr., 19, and Edison, 16, toward Wahiawa was speeding Tuesday night when it ran into the truck.

• Long, straight stretches of the road allow vehicles to build up speed that is excessive for sections of the road that include sudden, tight turns and a series of hills and dips.

• It is not a "limited-access highway," meaning cars or trucks can pull off or onto the road anywhere along the route, and with little or no warning. The driver of the truck involved in Tuesday's crash told investigators he was merely trying to cross the road when the car slammed into him.

• Long stretches of the road are unlighted, including the site of Tuesday's crash.

Of the 23 major accidents on Kunia Road between August 2003 and August 2004, eight were attributed to inattentive driving, seven to misjudgment and one each to alcohol, medical problems or fatigue. No single primary factor was listed in five of the incidents.

Kunia Road also was the site of one of the deadliest crashes in state history.

On July 24, 1982, five people were killed and two were critically injured when a speeding car rammed another from behind, then veered into an oncoming car near Kunia Camp.

The deadly nature of rural roads was highlighted by the study released yesterday by The Road Information Program, or TRIP. It found that safety improvements on rural, non-Interstate routes have lagged, although driving on all U.S. roads and highways has become less dangerous since 1990, according to the agency's review of federal highway data.

"The nation's rural roads ... are exposing rural residents and visitors to an unacceptable level of risk," said William Wilkins, TRIP executive director. "We know how to make rural roads safer. What is missing is adequate funding for road safety projects that will save numerous lives."

Among other things, the study found that:

• Some 52 percent of the 42,301 average annual traffic deaths from 1999 through 2003 occurred on rural, non-Interstate routes, although travel on those routes represents only 28 percent of miles driven.

• The death rate on rural roads in 2003 was 2.72 per 100 million miles driven, compared with 0.99 on all other roads.

• From 1990 through 2003, the death rate on all routes excluding rural roads decreased 32 percent. The death rate on rural roads declined by 21 percent during the same period.

• Many rural areas, particularly in the West and South, are gaining population, but roads in those areas are more likely than urban roads to have features that make driving hazardous. They include narrow lanes, limited shoulders, sharp curves, steep slopes and pavement drop-offs.

Advertiser transportation writer Mike Leidemann and USA Today contributed to this report. Reach David Waite at dwaite@honoluluadvertiser.com or 525-7412.