Preliminary Evaluation of Operational Performance of Different Types of High-Occupancy Vehicle Facilities in California Continuous Access versus Limited Access

High-occupancy vehicle (HOV) facilities have been regarded as an effective and environmentally friendly approach to improving the mobility and productivity of freeway systems in metropolitan areas. With 6 months of traffic data from more than 700 vehicle detector stations, the authors conducted a comparative study of the operational performance of continuous-access and limited-access HOV facilities at the route level in California. The evaluation results of both HOV lanes and adjacent general purpose (AGP) lanes include several operating characteristics of these lanes: (a) the ingress–egress areas in limited-access HOV facilities may affect the formation of bottlenecks along HOV lanes; (b) the speed on HOV lanes and the speed differential between the HOV and AGP lanes are statistically greater in continuous-access facilities than in limited-access facilities; and (c) the characteristics of speed–flow distribution of HOV lanes exhibit observable differences between the two types of HOV facilities, but those of AGP lanes are similar regardless of the access type. Furthermore, statistical analyses show that some performance measures at the route level, including the space mean speed and vehicle-miles-traveled share of the HOV lanes, are significantly different for HOV facilities with different access types.