Quantification of Travel Time Savings for Barrier Separated High-Occupancy Vehicle (HOV) Lanes During General Purpose Lane Incident Conditions

This project examined barrier-separated high-occupancy vehicle lane (HOV) travel time savings during incident conditions in Houston, Texas. Travel time studies, due to cost and manpower, are typically conducted infrequently and under non-incident conditions. Due to the high occurrence of incidents in large urban areas, travel time studies conducted under non-incident conditions underestimate the benefit of HOV lanes. During 2003, only an average of 17 percent of AM peak and 10 percent of PM peak periods were found to be incident free. Characteristics of the 9506 incidents reviewed from the incident database are described as a function of various characteristics. A total of 341 incidents in the study corridors were identified for further analysis and stratified into an incident matrix for each corridor by the number of lane blocked versus duration of incident. Travel time savings were analyzed using historical Automatic Vehicle Identification (AVI) data during incident conditions were compared to non-incident conditions for the range of incidents in the matrix. Travel time savings was estimated at 74 percent comparing HOV lane travel time savings during incident conditions over non-incident, combining all corridors and peak periods. Maximum travel time savings during incident conditions ranged up to 64 minutes in the AM peak and 49.5 minutes in the PM peak. An analysis of the 2003 AVI data (incident and non-incident conditions) estimated the benefit of HOV lanes in these four corridors during the peak periods at approximately $146,000 per day or approximately $38 million per year.