Out on the road, one trucker says many companies put unrelenting pressure on drivers to make sure loads are delivered on time.

“Driving a semi-tractor like this, any small mistake can take a life,” Abe Attallah, 28, from the Detroit, Michigan area, told ABC News’ “20/20.”

Tight deadlines can mean more hours behind the wheel with fewer opportunities to rest, and drivers are only paid when the wheels are rolling.

“You know, we are the most familiar and generally the safest people to drive next to on the road,” Attallah said. “But there are the circumstances where companies and drivers will put money ahead of safety.”

Log books are used in order to verify that a trucker is not spending too much time behind the wheel. According to Attallah, some drivers simply resort to falsifying their log books so they can stay out on the road.

“There is a lot of drivers out there who purposely break their logs and, you know, manipulate the log books to get more miles in the day,” he said. “They’ll show themselves sleeping, [but] then they are really out on the road.”

But modifying these log books can have tragic consequences.

This July, a speeding trucker in Illinois crashed into three vehicles, killing five people. The truck driver was charged with falsifying his log book. Prosecutors said he had actually been on the road for 12 straight hours.