Transcript for Fatigued Truckers and the Deadly Consequences
How many times has this happened to you? You're driving along, and one of those rigs barrels past you, shaking your car. So, tonight, we ask, how fast are trucks really driving? Tonight, Matt Gutman flying high above the interstate in the "20/2 "20/20" speed trap. Reporter: "20/20"'s on the chase, out with the Ohio state highway patrol, using air power to declare war on reckless truckers. At 3,500 feet above I-70 outside Columbus, sergeant George king uses a stopwatch and white marks on the road to spot violators. Following too close, that's going too fast. It looks like an oversize load. Reporter: King zeroes in on this 18-wheeler barreling down the highway at 77 miles per hour and tailgating a car. Closing in on a dark blue, white box. Following too close, .34 seconds. Reporter: I'm now with the ground unit, and sergeant Reimer jams his cruiser into gear. This guy's Goin' so fast. We're flying right now, trying to catch up. You can see how fast we're passing these trucks. The trucker pulls over and he's not happy. I'm Matt from ABC news. How are you? I don't need to be on the news. They clocked you going 77 miles an hour and tailgating behind a car. Do you think it's hazardous? Yeah. Just trying to catch up with a semi-trailer up ahead. Reporter: The cops also nail this trucker for tailgating. He's pulled over and cited. Did you notice that you were too close to someone? Well, sometimes you have to do that when you're, like, passing another car. Reporter: Cracking down on potentially dangerous truckers is a top priority. In 2012 alone, there were more than 330,000 large truck crashes in the U.S. -- Nearly 4,000 fatalities and more than 100,000 injuries. In most cases, it's the truck driver who survives. You have a truck that weighs 80,000 pounds. What happens when it collides with anything else? It's catastrophic. Looks like a bomb went off, right? Yeah, pretty much. It's a terrible accident. It's two vehicles and a Walmart truck. Reporter: It was this horrifying crash in June that turned the national spotlight on a leading cause of truck crashes -- tired drivers. At 1:00 A.M. On the New Jersey turnpike, a Walmart truck sped through a construction zone going 20 miles over the limit and plowing into the back of three vehicles -- including a limo bus carrying a group of comedians. Comedian Tracy Morgan in critical condition right now. Reporter: Superstar comedian Tracy Morgan and two others were critically injured another comedian was killed in the crash, 62-year old James McNair -- a longtime friend and mentor to Morgan. My dad was big on pictures. You can see in that signature smile in almost every picture. Reporter: News of the crash ripped a hole in the lives of McNair's kids, Jamel and Danita. Just hard to sometimes even, you know, find the words. The fact that he's not here anymore, I feel like I lost my best friend. Reporter: The family was shocked by what they learned about the Walmart driver, Kevin roper, who has pleaded not guilty to charges related to the crash. It turns out that roper had commuted over 700 miles from his home in Georgia to the Walmart facility in Delaware before he even punched in. Police say roper had been awake for a full 24 hours when he slammed into Morgan's limo -- an allegedly deadly combination of fatigue and velocity. Whoever's responsible, to be held accountable for it. Reporter: The question the mcnairs are now asking -- did Walmart, the largest truck operator in the country, keep proper track of roper's hours? They have to make sure that their drivers are doing so in a responsible manner. And that means making sure your drivers are not driving in a way that they're dangerous. Reporter: Walmart says it is "Cooperating fully in the ongoing investigation" and that "If it's determined that our truck caused the accident, Walmart will take full responsibility." Despite the huge toll caused by trucking accidents -- the industry trade group maintains that safety is a top priority. Two thirds of accidents involving commercial vehicles are actually caused by a vehicle other than the commercial vehicle. Driving a semi-tractor like this, any small mistake can take a life. Reporter: Out here on the road, trucker Abe attallah says so many companies put unrelenting pressure on drivers to deliver loads on time. There are the circumstances where companies and, and drivers will put money ahead of safety. Reporter: And attallah says he found that out firsthand on a frigid February night this year. The trucker with the spotless record was in the middle of a 400-mile run to Wisconsin, hauling a load of tomatoes for his company, k&b. All of a sudden, he says, he notices himself drifting dangerously into a type of unconsciousness that truckers call "Micro sleeping." Basically, your eyes are open, your hands are on the wheel, but your brain shuts off for three to five seconds. Reporter: Attallah says he was so worried that he might cause an accident, he pulled into a truck stop and called the k&b dispatchers. Hey, man, we got a bit of a problem, dude. I'm starting to fall asleep going down the road here. Reporter: But get a load of this -- the k&b dispatchers instead of telling him to just get some rest, hot potato Abe from one dispatcher to another. Each of them with the same advice -- Get some coffee, 'cause we don't have a choice on this. Did you drink some coffee? Walk around the truck, do something? I already did that earlier, man. Reporter: Now the last dispatcher is relentless, even refusing to listen to attallah. Let's get out and get some fresh air, what is it, about 10 degrees outside? That'll wake you right up, right? I can get you all fired up, if you want me to make you angry I can get you woke up that way. He's not getting your goat? No, I knew before I made the phone call I was not moving that truck anymore until I got some sleep. I'm telling you, I'm not safe to drive, at the moment. Okay, well then here's the deal, we don't have a choice on this. That's not how it works here at k&b. I say I'm not gonna hurt anybody out here on the road. You know what? You don't need to jump to that. That's dramatic I don't need this morning, right? You are being honest. And he is saying, "Well, that's dramatic bullcrap, I don't need this." Yeah. I mean, it was very clear at that point that he just cared about that load and making that money. Reporter: But the dispatcher still isn't through. Listen as he now ups the ante -- threatening to dock attallah's pay. You wonder where your paycheck went this week? You know, it came down to where it went tonight. Are we clear on that? Yes, we are clear. Okay, I don't know if you have a wife at home, and she's gonna ask you "Hey, what happened this week?" Reporter: Finally k&b agrees to send another driver to rescue the load of tomatoes so attallah can finally get some sleep. And ultimately the company didn't dock his pay. K&b refused to talk to us about how its dispatchers handled attallah's case. But we did get a very clear response from the head of the trucking lobby -- Well, the driver was obviously doing the right thing. And the dispatcher was obviously doing the wrong thing. There's just too much at stake when you have a commercial vehicle going down the nation's highways with a fatigued driver. Reporter: Attallah decided to quit k&b a few months ago. He's still driving a truck, hauling loads between the booming oil shale fields of western Pennsylvania. He now says he's proud of exposing one of the industry's biggest dangers and of keeping his record and his conscience clean. This is the side of trucking that people never see. You know, this is the kind of treatment that drivers have been putting up with for so long, because we know that our jobs are on the line here.
This transcript has been automatically generated and may not be 100% accurate.