Roadway deaths in Georgia have increased by nearly a third so far this year, a troubling jump that transportation officials and experts are struggling to explain.

They say some preliminary data adds up to a big worry — more irresponsible behavior behind the wheel, which can include distracted driving, impaired driving and speeding. They point to increases in single-car fatalities and accidents in which the vehicle veered out of its lane.

They also fear more people are driving while using their smartphones, which offer an ever-growing array of enticements, including texting, emails, Facebook, Twitter and, ironically, apps that provide road condition updates.

“That leads us to the conclusion that the leading cause of this fatalities increase is an individual responsibility issue,” said Karlene Barron, spokeswoman for the Georgia Department of Transportation. “That is why we are encouraging drivers to buckle up, turn off the cellphone and be alert.”

The Atlanta Journal-Constitution got an exclusive look at the GDOT figures. Overall, the first quarter of the year saw a 31 percent increase in roadway deaths to a total of 295 fatalities, which is 70 more than this time last year, according to GDOT.

The sudden spike has caught the attention of state transportation officials, coming after nine years of declines in roadway deaths and just before the high-travel summer season. Officials are crafting a $250,000 road safety campaign for the summer.

“Am I concerned? Absolutely,” said Harris Blackwood, director of the Governor’s Office of Highway Safety. “Am I panicking? Absolutely not.”

A welter of theories

GDOT officials emphasize they don’t know exactly what’s causing the increase, and that it may be a multitude of issues. Essentially, they practice an imperfect science, trying to extrapolate driving behavior patterns from an abundance of accident statistics. Officials depend on officers at the scene for correct information and for their departments to forward the data to the state.

Not every fatality occurs at the scene, and the follow-up information does not always make its way to GDOT. Pinning down distracted driving can be a challenge. In some cases, it is clear that a person was texting while driving. But in others, who’s to know whether the person was turning around to yell at the kids or changing the radio station?

Still, GDOT has spotted some worrisome trends in the data thus far. They found a growing number of people were not wearing seat belts when they crashed and died. More of them failed to maintain their lanes, and more fatalities involved just a single car.

Experts say single-vehicle crashes more often point to problems with individual driver behavior, compared with other causes such as weather, mechanical error and roadway design.

These single-car fatalities include the death early this month of Robert Lewis Burns Jr., a founding member of the iconic country rock band Lynyrd Skynyrd, who drove his car off the road into a tree in Bartow County. Police say he was not wearing a seat belt.

Despite statistics that show the vast majority of drivers wear seat belts, the new figures show an increasing percentage of people who died in crashes had not buckled up. Little more than a third of people who died in crashes were clearly wearing seat belts, according to the GDOT figures. The remainder were either not wearing them or investigators could not make a determination because of the wreckage.

The figure represents a slide from 2012, when more than half of people in fatal wrecks were clearly wearing seat belts.

“We had thought the message of buckle up had permeated among drivers, but based on this data it’s worth pushing out that message again,” said Andrew Heath, the state’s traffic engineer.

Georgia’s increase has set off a welter of speculation on the cause. Blackwood looked to the improving economy, suggesting that more people are employed and driving more. Cheaper gas prices may also play a role, leading people to hit the road more often, he said.

Georgians are indeed logging more vehicle miles this year, but GDOT officials say they are looking closer at the increase in single-vehicle fatalities. They rose from 49 percent of all fatalities in 2009 to 60 percent this year.

Georgia State Patrol has its own theory on one factor that may be contributing to this year's surge. Spokesman Capt. Mark Perry pointed to a more-than-average number of accidents this year that resulted in multiple fatalities.

This month, three members of a rock band died when their van ran off I-85 in Jackson County, drove down an embankment and struck a tree. The driver of the passenger van fell asleep, police said.

“I’d like to see this trend level out,” Perry said. “But unfortunately during the summer months, there are more families traveling in vehicles. More people traveling together. So there is more chance of this kind of tragedy occurring.”

Increases in metro Atlanta

Some of the most marked increases in the state are occurring in the northeast and southwest counties of metro Atlanta, said Heath. GDOT is mapping the exact trouble spots.

Officials stressed that data for one quarter does not constitute a trend. They are still drilling down into the numbers and watching to see whether the surge continues.

Some transportation experts doubt the spike will sustain, considering it has not been accompanied by some major change in driving laws in Georgia. Some suspect it may be a statistical blip or a temporary spate of tragic luck on the roads.

Michael Rodgers, a transportation expert at the Georgia Institute of Technology, said it’s statistically conceivable that last year’s quarterly figure may have been especially low, and this quarter’s especially high. The variance may balance out over time, he said.

“There might be a chance that something is going on here,” Rodgers said, “but there might be nothing going on.”

A more recent look at Georgia fatalities, for April 16, showed the percentage of increase had decreased a bit to 25 percent above last year.

A national trend

Georgia is not alone in seeing an increase in road deaths this year. There has been a 10 percent bump nationally, according to the National Safety Council. South Carolina officials told the AJC they are seeing a 14 percent hike. But it’s still unclear why Georgia remains so high above the national average.

National Safety Council President Debbie Hersman speculated that Georgia’s increase could be linked to the recent rise in speed limits on some state highways. This year, GDOT raised the limits to as high as 70 miles per hour on 95 miles of metro Atlanta freeways.

But GDOT’s Heath said the increases in fatalities are concentrated on other state routes not included in the change of speed limits.

Indeed, some of the biggest jumps in fatalities were seen on state routes that are not interstates. They saw 44 more deaths in the first quarter, a 42 percent jump, over last year, according to the GDOT numbers. These state routes are traditionally among the most dangerous in metro Atlanta, including Buford Highway in DeKalb County, Tara Boulevard in Clayton County, and South Cobb Drive.

For now, state transportation officials are keeping an eye on which way the numbers move. “I’m watching it every day,” said Blackwood.