Due to their sheer size and weight, semi-trucks provide a much larger hazard on the road than any other type of vehicle. Trucks that jackknife can become a rolling wall, crushing everything that is in its path. A tanker may wreck and spill potentially hazardous materials onto the road, making it unsafe for drivers and others in the area. A truck, unable to slow as quickly as a passenger car, could cause a pile-up from failing to stop quickly enough.
Most truck accidents result in a fatality. A commercial semi-truck can weigh in excess of 80,000 pounds. When compared to the average 3,000 pounds that a car weighs, you can understand the devastation this would cause.