Who Chooses to Carpool and Why?

The debate over high-occupancy vehicle (HOV) and high-occupancy toll lane efficiency has raised questions about whether HOVs should be given preferential treatment on managed lanes and the potential impacts of different preferential treatments. This research questions why people choose their mode of travel by examining characteristics of carpoolers and single-occupancy vehicles, reasons for their travel mode choice, and carpool formation, on the basis of a survey of travelers in Dallas-Fort Worth and Houston in Texas. Carpool users rated the ability to use HOV lanes as the most important factor in their decision to form a carpool. Enjoying traveling with others ranked second, followed by reasons such as saving time, helping the environment and society, and sharing vehicle costs. Carpool partner matching programs, employer carpool incentives, and preferred parking at work were generally the least important factors in travelers' consideration of carpooling. The importance of various factors changed significantly if the respondent was on a work or commute trip versus other trip modes. Travelers on work or commute trips ranked travel time savings and cost sharing much higher, as expected, because of their frequent travel during peak hours. The data also support evidence of a significant amount of “fampooling,” with nearly 75% of carpools consisting of family members. The implications of these findings are discussed.