Success factors and decision issues for high-occupancy vehicle facilities

Factors affecting success of high-occupancy vehicle (HOV) lanes are explored. An earlier study was conducted to support future HOV choices in Chicago, which has no such facilities, in part because of concerns about risks and possible negative outcomes. HOV facility performance characteristics were assembled and updated. Comparisons of closed and operating HOV lanes, as well as case studies, highlighted the importance of HOV lane utilization as a success factor and suggested 800 to 1,000 HOV's per lane-hour as typical of the success-failure boundary. A number of key factors in the HOV planning and decision process were explored. HOV lanes were found to be generally favorable for transit; flexibility of access restrictions (such as occupancy requirements and tolling options) makes it feasible to assure acceptable lane utilization levels; HOV2+ seems to be the access restriction most feasible in typical markets; evidence on formation of new carpools is mixed (this question warrants more study); lane addition rather than conversion is usually essential for feasibility; and organized opposition to HOV lanes demands careful planning and promotion of utilization. Criteria for identification of more promising HOV facility locations are provided.