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Publication Number:  FHWA-HRT-13-053    Date:  May 2013
Publication Number: FHWA-HRT-13-053
Date: May 2013


Exploratory Advanced Research Program

Casual Carpooling Focus Group Study


These concluding observations are organized by the conceptual framework that guided this research study design (discussed briefly in the methodology section), that is, the system, individual, and environmental factors that influence casual carpooling behavior.

Environmental factors (community characteristics such as geographic location, prevalence of transit, HOV and other managed lanes, and parking availability at homeside meeting places)

When it comes to casual carpooling, regardless of the location, the researchers for this study found that for casual carpooling to begin in the first place requires several environmental factors: a centralized activity center for a destination location, a low-congestion HOV lane that provides a time-saving advantage (and sometimes cost-saving advantage as well), and readily available backup modes of transportation. Table 4 summarizes the environmental characteristics of the casual carpooling systems by each of the study locations.

Table 4. Characteristics by study region.

Study Regions Casual Carpool Line Location Person Requirement Payment Required Challenges Alternate Modes of Transportation
Washington, DC Fort Belvoir, I-95 HOV-3 No No casual carpooling to Fort Belvoir Metrorail (to Franconia) Metrobus Commuter rail (Virginia Railway Express)
Dumfries, I-95 HOT lane conversion concerns  
Houston, TX Northwest Station Park-and-Ride, SH 290 HOV-2 HOV-3 No HOT lane conversion concerns Transit on return trip. Bus
Addicks Park-and-Ride, I-10 HOV on HOT lane No Road expansion, HOT lanes reduced congestion Transit on return trip. Bus
San Francisco, CA Downtown Oakland HOV-3 on tolled bridge Yes Bridge toll Transit on return trip. BART/Bus—Multimodal transportation (transfers required)
Vallejo HOV-3 on tolled bridge Yes Two bridges/two tolls Transit return trip. Ferry BART/Bus—Multimodal transportation (transfers required)


The physical environment, however, can be a detractor to participate in casual carpooling—on rainy, icy, or otherwise inclement days, passengers would opt for transit rather than wait for a ride.

System factors (the naturally occurring nature of the system, employer-based programs that support casual ridesharing, or other institutional factors that contribute directly or indirectly to the system)

Overall, the primary benefits are the time savings for both passengers and drivers associated with the use of the HOV lanes by drivers, thereby avoiding congested traffic, and the cost savings associated with not paying tolls or paying lower tolls (passengers and drivers), parking (passengers), gas and car maintenance (passengers), and transit fares (passenger and driver).

The casual carpooling system is successful when participation levels by drivers and passengers are high enough to satisfy the travel needs of both groups. In essence, casual carpooling works when there is an adequate supply (vehicles with drivers) and demand (passengers). Therefore, it is easy to see how certain system factors can upset or “break” the casual carpooling system.

Individual factors (social identity, individual expression, culture, social bonding, attitudes and beliefs, and personal values)

For those who participate, the casual carpooling experience is not only a form of transportation, but one that encourages engagement on a personal level. Independently of whether one chooses to engage in conversation (initiated by the driver) or not, the option to do so (again, only with a willing driver) is a characteristic of casual carpooling that is valued among those who participate in it. Casual carpooling is viewed as something interesting, a conversation starter, and because those who participate in it also trust it, it is an experience they readily defend and share with their friends, family, and coworkers.

Being part of a unique community was viewed as a benefit expressed by participants in all locations, but those participating in Houston and Vallejo, especially, view their communities as being “special” to the degree that deeper relationships within and outside of the casual carpool are sometimes formed. These relationships include a more personal level of interaction during the commute (more talking, being courteous by offering the use of the car trunk, and dropping off passengers at their final destination during bad weather) and participating in social gatherings.

Overall, community and environmental factors do not drive participation. Instead the focus is more on the personal benefits of casual carpooling, for instance, time savings to commute to and from work, flexibility of one’s daily schedule, savings on cost, as well as, in some cases, the social component, like networking or developing friendships.


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