(CBS News) Veterans have many difficulties readjusting to civilian life. Thousands of them have trouble with the simplest things, such as driving a car.
It can be a terrifying ordeal for some vets.
Former Marine Sgt. Eric Campbell has knee braces, the obvious physical evidence of his two tours of duty in Iraq. Less obvious are the psychological effects of those experiences. But they are there.
Recalling a moment from one of his tours, Campbell said, "This van started coming down the road toward our roadblocks and our translators were translating, 'Stop, stop, stop your vehicle.' We ended up firing on this van. There was a dad driving, a mother in the passenger seat, the pregnant sister of the mother, and two children. The only one that survived was the pregnant sister."
Events like that have left Campbell with post-traumatic stress disorder, or PTSD. After fighting in Operation Iraqi Freedom he's lost some of his own. Anxiety has made it impossible for him to drive. "I would hit potholes and it would throw me into a flashback."
Campbell and his fiancee Amy live 20 miles outside of Fresno, Calif., in a tiny trailer they share with her three kids and two of his own. His inability to drive puts an increased burden on her, and makes a difficult situation, worse.
Campbell is one of more than 200,000 vets who've sought treatment for PTSD. Roadside bombs and improvised explosive devices in Iraq and Afghanistan made driving treacherous in those war zones and back home veterans have to navigate a new set of hazards.
Dr. Steve Woodward runs a study on veterans and driving out of the Veterans Affairs hospital in Palo Alto, Calif. Woodward said, "They'll do things like drive in the center of the road. This was something they were taught to do, to stay away from the sides. They'll drive very fast, they'll sometimes go through red lights."
Campbell is part of Woodward's study. He gets wired up to monitors that check his heart rate and breathing behind the wheel, while a therapist sits beside him.
To avoid influencing the outcome, CBS News wasn't permitted in the car while the study was being conducted, but afterward we drove with Campbell and therapist Marc Samuels to get a sense of the road through this veteran's eyes.
Campbell said, "If a vehicle were to stop in front of me, I can't go anywhere," Campbell said. "Because there was a vehicle behind me, I'm trapped." Traffic jams, he said, "... are not good for me, no."
It was an eye-opening ride. Situations invisible to most drivers trigger alarm bells for Campbell. He's been trained to notice the smallest discrepancy. Campbell explained, "If you have fresh paint on a certain area and old, ratty paint everywhere else, you're like, OK, what happened to that spot? Who planted a bomb there?"
Electrical boxes on the sidewalk. People on cell phones. The tiny silhouette of a construction worker in the distance can look like a sniper. Virtually anything on the road can be a flashpoint for a combat veteran.
But it's possible to live with those anxieties, Samuels said. "I'm not going to say 'overcome' because they are not going to go away," he said. "I can't cure his PTSD. But what we can do is address the issues that are underlying it to allow those symptoms to be manageable."
For Campbell, that means continually reminding himself he's no longer in danger. He said, "It's safe, we're in America, bombs aren't going to go off. So it's given me a little bit more freedom. I want to be able to take over driving if she's tired. I know I will never be 100 percent, but I want to be better."
To watch Lee Woodruff's report, click on the video in the player above.