Role of Preferential Treatment of Carpools in Managed Lane Facilities

V.D. Goodin, M.W. Burris, C.M. Dusza, D.H. Ungemah
College Station, TX: Texas Transportation Institute
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This project summary report summarizes the research performed in Texas Department of Transportation (TxDOT) Project 0-5286. This project investigated the role of carpools in priced managed lanes and the trade-offs between carpool exemptions and other project objectives. Allowing exempt users such as carpools in the managed lanes requires an evaluation of revenue impacts as well as mobility interests such as person movement, operations, and emissions. Researchers reviewed the state-of-the-practice, conducted a stated-preference survey, developed a predictive demand model, and assessed mobility, revenue, and environmental impacts. They found that the more favorable the carpool preference policy, the higher the person throughput but the lower the revenue generated. Determining the right carpool policy depends upon the managed lane project objectives and relative weights of each. Agencies need to consider several operational, enforcement, and equity factors that influence decisions about carpool preference. Also, carpool preferences in managed lanes can influence carpooling behavior; the most common reason for carpooling is having access to the high-occupancy vehicle (HOV) lanes, particularly for work trips.