Improving Safety Analysis Methods to Better Address Traffic Conditions and Dynamic Countermeasures

Considerable research has recently been devoted to establishing relationships between crashes and various traffic flow characteristics for freeway segments. Most research has focused on determining the relationship between crashes and highway traffic volumes. Little attention has been focused on the relationships of vehicle density, level of service (LOS), vehicle occupancy, v/c ratio, and speed distribution. Using data from rural and urban freeway segments in Virginia, this study will evaluate the relationship between crashes and quality of flow aggregated at the hourly level. This research will also develop a methodology that uses disaggregated traffic, geometric, and control information at sub-daily aggregation intervals to examine safety. The methods developed in this study will facilitate the assessment of a facility where conditions are different for different times of day.