PHOENIX (3TV/CBS 5) - Arizona Department of Public Safety officers are alerted to wrong-way drivers an average of three times per day. And when they catch up to those drivers, they find that fewer than half of them are impaired.

That is according to a CBS 5 Investigates analysis of wrong-way driver calls since January 2017. And it goes against the common perception that a vast majority of wrong-way drivers are drunk or on drugs.

[WATCH: Wrong way driver solution may be new interchange design]

"I had not had anything to drink or any pills or anything like that," said a woman named Gloria, whose last name we agreed to conceal so she would speak to us.

"I was coming from the Dollar Tree and heading west, and I needed to go on the second right. And I made the first right and not the second right," said Gloria.

She ended up driving down the off-ramp, toward oncoming traffic from Interstate 17.

"Seeing cars coming at you like that is just terrifying," she said.

Between 2017 and the middle of 2019, Arizona Department of Public Safety officers were alerted to nearly 3,500 wrong-way drivers on Arizona streets, highways and freeways. In nearly 70% of the cases where they had contact with the wrong-way drivers, those drivers turned out to be sober.

[MAP: 2019 wrong-way incidents in Arizona]

According to our analysis, the impaired drivers were much more likely to crash than the sober ones. In cases that resulted in crashes, more than 60% of the drivers were impaired by drugs or alcohol.

But something is causing sober drivers to head down off-ramps into oncoming freeway traffic. Factors that DPS has identified include age, fatigue, inattention and drivers who are not familiar with the area.

"It was right there," said Kathy Huff, who survived a collision with a wrong-way driver on the U.S. 60 three years ago. "I cranked the living daylights out of the wheel and stomped on the brake. We hit corner to corner," she said.

The woman who struck Huff had struck two other cars. But she was also sober.

"She was 78 years old and had done a U-turn near Power Road," said Huff.

The freeway interchanges that both this woman and Gloria were using are known as "Full Diamond" interchanges. They are considered efficient and safe designs. But they also give drivers two opportunities to enter the freeway going in the wrong direction.

[RELATED: Phoenix area freeway system not to blame for wrong-way drivers, says expert]

"There is no interchange, no infrastructure that is going to completely eliminate the chances that someone will take a wrong turn, say, on an off-ramp," said Doug Nintzel, who works for the Arizona Department of Transportation.

Nintzel says the state is focusing on placing more and larger "Wrong Way" signs on the interstates and off-ramps, as well as adjusting the height of those signs, so they are visible from cars and trucks.

[READ MORE: Thermal cameras along I-17 have begun detecting wrong-way drivers]

The state is also testing an early warning system on I-17, which alerts ADOT and DPS officials immediately in the event someone drives the wrong way down an off-ramp or along the freeway.

"We're trying our best to use technology to reduce the risk of the wrong-way crashes we are seeing," said Nintzel.

But a relatively new interchange design may also help. ADOT is in the process of building three "Diverging Diamond" interchanges. One is at I-17 and Happy Valley Road, and two are along the new Loop 202 near Ahwatukee.

[RELATED: New type of traffic interchange in Phoenix will have you driving on the left]

During tests in other states, these interchanges appear to reduce the number of collisions, as well as eliminate the chances a driver enters the freeway heading the wrong way.

Nintzel says that is not a primary reason why ADOT is adding diverging diamonds to its interchange lineup, but he says the department is aware of this added benefit.

"There's no doubt that we are pleased with what the design shows in terms of the fact that it will be challenging for someone to make that turn to become a wrong-way driver," said Nintzel.

[RELATED: Why there are no wrong-way detection cameras on Loop 101]

He says ADOT continues to study the problem, and it does not appear that the problem is going away. An analysis of the U.S. Department of Transportation Fatal Accident Reporting System Data shows the number of deaths on Arizona roadways due to wrong-way drivers increased from 11 in 2014 to 21 in 2017, which is the most recent year data is available.

[APP USERS: Click here for interactive map]

Morgan Loew's hard-hitting investigations can be seen weekdays on CBS 5 News at 6:30 p.m. and 10 p.m.

Copyright 2019 KPHO/KTVK (KPHO Broadcasting Corporation). All rights reserved.

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