CURRENT PRACTICES IN EVALUATING FREEWAY HOV FACILITIES

Evaluating the impact of high-occupancy vehicle (HOV) facilities has been a topic of considerable interest and discussion among transportation professionals in recent years. Project objectives, potential evaluation criteria, appropriate effectiveness measures, and data collection methodologies have been a major focus of sessions at national HOV conferences, as well as of numerous reports. A review of the major before-and-after evaluation studies that have been conducted on HOV facilities in the United States since the opening of the Shirley Highway (Northern Virginia) bus lane in 1969 is presented in this paper. The review includes a summary of the approaches used with the different evaluations and the identification of common elements. The results of this analysis advance understanding of the major components that should be considered in the design of HOV evaluation studies. The paper should prove beneficial to agencies in the process of designing before-and-after evaluation programs for new HOV facilities. In addition, it should be of help to transportation professionals in areas that have operating HOV facilities who may be interested in improving their current evaluation methods.