This report defines the problem of lane change crashes in the United States (U.S.) based on data from the 1999 National Automotive Sampling System/General Estimates System (GES) crash database of the National Highway Traffic Safety Administration. The results from this analysis provide a basis for related future research in the U.S. Department of Transportation’s Intelligent Vehicle Initiative. Lane change crashes are defined in this report as two-vehicle crashes that occur when one vehicle encroaches into the path of another vehicle initially on a parallel path with the first vehicle and traveling in the same direction. Such encroachment results from various vehicle maneuvers including typical lane change, merge, pass, drift, turn, and leave or enter a parking position. Approximately 539,000 two-vehicle lane change crashes occurred in the U.S. in 1999. The analysis of pre-crash scenarios identified the seven most common scenarios that accounted for about 88% of all two-vehicle lane change crashes. Ten percent of “typical lane change” crashes involved large trucks changing lanes and light vehicles going straight; about 5% of these crashes involved the reverse combination. Similarly, trucks were turning and light vehicles were going straight in 10% of the “turning at junction” crashes; the reverse combination was reported in only 1% of these crashes. The highest involvement of trucks was observed in the “merging” scenario, accounting for 42% of these crashes. Finally, the physical setting of the seven scenarios was described in terms of the number of travel lanes per direction of travel, crash relation to junction, posted speed limit, roadway alignment, and roadway profile. The report also examines possible contributing factors using available GES variables. (Author/publisher)
Abstract