SAFETY IMPACTS ASSOCIATED WITH INSTALLATION OF HOV (HIGH OCCUPANCY VEHICLE) LANES

An evaluatory study is reported of the traffic safety of freeway High Occupancy Vehicle (HOV) lanes that are not separated by physical barriers from adjacent, general-purpose traffic lanes. The study attempted to determine the causes of any changes in safety conditions due to the operation of such lanes, and to identify possbile actions to mitigate any adverse safety impacts. The study focused on 2 HOV lane operations in the greater Los Angeles area, both of which operations have been implemented through partial removal of the left median shoulder and restriping of the lanes. It was found that the HOV operation on one route had no adverse effect on safety conditions, but that there is a significant migration of accident locations. The patterns of traffic congestion on the route had changed but not been alleviated. In the second operation, HOV lane contributed to a 2% increase in accidents on that route. The details of the study fingings are presented and relate to the accident frequencies; patterns of accident characteristics; accident locations, causal factors in changing accident concentrations; and accidents and changing congestion patterns.