One method of evaluating the cost-effectiveness of high-occupancy vehicle (HOV) lanes is examined. By use of MicroBENCOST, a planning-level economic analysis tool, and more than a decade of HOV lane documentation in Texas, benefit-cost ratios for all HOV lanes in the state are developed. Estimates of benefits using actual cost data are compared with benefits calculated using the "Highway Capacity Manual" techniques incorporated into the program. Each HOV lane is assessed as both a stand-alone project and an alternative to two additional general-purpose freeway lanes. The results show that the potential benefit of either alternative varies significantly by corridor. One key variable is manipulated in order that the impact of the HOV lane under increasing total daily traffic in the corridor can be determined. The findings show that the role and effectiveness of the HOV lane vary significantly by type of lane (reversible, contraflow, concurrent) as total corridor traffic increases. These findings may be useful in examination of corridors where HOV lanes are being considered.