Abstract
This paper addresses safety issues associated with High Occupancy Vehicle (HOV) lanes constructed along freeway medians, without physical separation from adjacent traffic. Data associated with operation of such an HOV facility in Southern California are analyzed relative to the pattern of accidents on the facility and the potential role of congestion. Detailed analyses of accident characteristics point out that potentially false conclusions regarding the safety of HOV lanes can be drawn from simple analyses that are based on aggregate measures of accident frequencies and assumed traffic volumes.