Every type of truck on the road can potentially be involved in an accident. Commercial trucks, however, are what people often mean when they speak of a truck accident. If you are listening to the radio in the morning, for example, and the announcers talk about a truck accident on the road, they are almost certainly referring to an incident with a large commercial truck.
Why? These types of trucks are prone to certain types of accidents that can pose dangers to passing motorists and tie up traffic for miles around. A rollover, for example, can spread a truck across several lanes of traffic. So can a jack-knife, where part of the truck is perpendicular to the other part. Cargo is more prone to spill in incidents like this, and the flying cargo itself can pose a danger to passersby. If the trucks are carrying flammable liquid, the potential danger of fire or chemical spills can be great. So one of the reasons for the radio announcements is to warn motorists to take other routes to avoid the danger—or plan for the delays that can ensue from a truck accident.