Data associated with over 9000 accidents involving large trucks and combination vehicles during a two-year period on freeways in the greater Los Angeles area are analyzed relative to collision factors, accident severity, and incident duration and lane closures. Relationships between type of collision and accident characteristics are explored using log-linear models. The results point to significant differences in several immediate consequences of truck-related freeway accidents according to collision type. These differences are associated both with the severity of the accident, in terms of injuries and fatalities, as well as with the impact of the accident on system performance, in terms of incident duration and lane closures. Hit-object and broadside collisions were the most severe types in terms of fatalities and injuries, respectively, and single-vehicle accidents are relatively more severe than two-vehicle accidents. The durations of accident incidents were found to be log-normally distributed for homogeneous groups of truck accidents, categorized according to type of collision and, in some instances, severity. The longest durations are typically associated with overturns.