In this study, trucks or large trucks are defined as straight trucks (ST-TR) also known as single unit trucks having a single body without any hitch between the loading section and front driving mechanism, tractor trailers (TR -TR) having two bodies coupled by a hitch, and twin tractor trailers (TW-TR) with front driving mechanisms towed by a double trailer. Vehicle miles of travel (VMT) for these trucks have been steadily increasing for the past five years (1986-1990) showing a continuous growth in transportation goods both inside and outside of the State of Virginia.

The objective of this research is to identify the major factors associated with truck overturns occurring on which occurred between 1986 and 1990, on the main line of the Virginia Interstate System in general and 1-81 in particular.