Major changes in the trucking industry have resulted from federal legislation that relaxed the regulation of trucks in interstate commerce, allowed the use of double-trailer combinations nationwide oninterstate highways, and required states to regulate trailer lengthinstead of overall length. Because michigan has long had extremely liberal truck size and weight regulations, its experience with trucksafety is of significant interest. A project by the university of michigan and michigan state university was undertaken to develop statistical information on accidents, travel, and the risk of accident involvement for michigan-registered trucks in michigan. The study objective was to calculate disaggregate truck accident rates by road class, day or night, and urban or rural operating conditions for tractors without trailers (bobtails) and in single- and double-trailer configurations. Major findings included the following: bobtails consistently have the highest accident rates; all-accident and casualty rates for single and double configurations are similar to one another;the most significant and consistent factor associated with truck accident rates was the roadway class (highest rates on the "local" road system, lowest on limited-access highways); urban accident rates were lower than rural rates; night rates were higher than day rates for casualty accidents but lower for all accidents; and tractor drivers aged 19-20 have an accident rate five times the average. The findings indicate that differences in truck safety by roadway class are more important than those between singles and doubles. Discussion and recommendations concerning improvements in truck accident and exposure data as well as further work on the relationship between truck accidents and geometry are included. This paper appears in transportation research record no. 1322, Large vehicle safety: transit and trucks 1991
Abstract