An analysis of accident records indicated that auto-utility trailer (A-UT) combinations are involved in a disproportionately high number of traffic mishaps. Locations which have a history of accidents involving A-UT vehicles indicated that differential crosswinds and unanticipated driving maneuvers contribute to the driver's loss of control. A-UT combinations contributed to the fatigue loss in pavement life approximately 50 percent as much as single-unit, two-axle, six-tire trucks (per vehicle). In general, this vehicle type constituted approximately three percent of the total traffic stream. Analysis of speed distributions indicated an equivalency factor for A-UT combinations equal to that for trucks for similar roadway types and topographical conditions.

Report Date


Report Number

No. 381

Digital Object Identifier



Offered for publication to the Highway Research Board.