Most of the 500,000 semi trucks accidents in this country are caused by some form of negligence, either by the driver, a smaller car, the truck manufacturer, or the maintenance crew of the truck company. Statistics show that while most semi trucks accidents involving a smaller car cause injury and death to the small car occupants, 75% of those accidents are caused by negligence on the part of that small car. That often occurs because passenger vehicle drivers don't realize how difficult it is to change directions, slow down significantly, or even stop a truck weighing up to 80,000 pounds. Even an improper lane change in front of a semi truck can lead to disaster in some cases. Sometimes the true cause of semi trucks accidents can only be determined by a truck accident lawyer with experience in this area.