The relationship between accidents and conflicts recorded by drive recorders

Traditionally, road accident statistics are used to assess the level of road safety and evaluate road safety programs. In some cases, the lack of good and reliable accident records have hampered detailed analyses. Video drive recorder (VDR) with high performance appeared in recent years, which can record various data including image of traffic environment, status and operations of drivers, velocity and acceleration of vehicles. The conflicts recorded by VDRs could be used to assess the level of road safety or evaluate road safety programs. The relationship between accidents and conflicts recorded by VDRs must been known in order to analyze traffic accident by making use of the conflicts recorded by VDRs. 50 VDRs were installed on 50 cars in Beijing to collect the conflicts. As a result, 1366 conflicts were collected in 193 days. The hourly distribution of conflicts and accidents in Beijing in 2001 and 2002 were analyzed. It indicates that there was a significant correlation between conflicts and accidents in Beijing on hourly distribution. Two parameters were defined to analysis the relationship between accidents and conflicts, which were Average Accidents per 10,000 Vehicle per Hour Everyday Annually abbreviated as A, and Average Conflicts per 10,000 Vehicle per Hour Everyday abbreviated as E. The linear model between the conflicts and accidents was established. But it didn't suit to describe the relationship between conflicts and accidents. According to the figure of traffic accidents and conflicts, traffic accidents were increasing as conflicts increased, but the degree of increasing were weakening as conflicts increased. P _EA = E/A was defined, and it was linear correlation with E. The relationship between P _Ed and E can be described as P _EA =αE+β. So the relationship between A and E would be described as A = E/(αE+β). It was a nonlinear model of relationship of conflicts and accidents. The nonlinear model can be used to describe more features of relationship between conflicts and accidents.