Carpooling

Carpooling occurs when two or more people occupy the same vehicle and travel between the same or similar origins and destinations. Carpools may consist of people of the same household (called intrahousehold carpools or fampools) or may consist of friends, coworkers, neighbors, or others who reside outside the household (interhousehold carpools). Carpool arrangements may occur relative to a specific trip and remain more informal in nature or individuals may make formal arrangements (including financial) to share rides on a regular basis. Much of the research on carpool behavior has focused on formal carpool arrangements for the work commute, although newer research has extended the focus to fampools and to understanding the characteristics of carpool trips for other purposes.

Although carpooling was encouraged by governments to conserve gasoline and rubber for military use during World War II, little is known about carpooling prior to the late 1970s, when carpooling was included as a separate mode choice option in the 1977 Nationwide Personal Transportation Survey. The oil crises of 1973 and 1977 brought about an interest in finding ways to decrease American and European dependence upon foreign oil. Since transportation accounts for the largest proportion of oil use, one of the best ways to decrease dependence was to find ways to reduce transportation fuel use. In addition, increased fuel costs led to growth in carpool use from the mid-1970s through the mid-1980s. This interest in learning new ways to lessen gasoline use led to the first waves of research on carpooling behaviors in the late 1970s and 1980s. This early research focused on the attitudes and preferences for different work commute modes and ways in which public and private policies could influence changes in transportation mode choice from single occupancy vehicles (SOV) to public transportation or carpooling.

The nascent carpool research used statistical models similar to those used for analyses of consumer behavior. Thus, economic models estimating elasticity of demand for carpooling (usually measured relative to the cost of gasoline) or psychological-related models measuring individual preferences for transportation mode choices and various incentives for switching to carpooling were used. This early research was used to measure the effectiveness of various public transportation management programs, such as developing high occupancy vehicle (HOV) lanes, monetary incentives, and workplace ridesharing programs. Shares of workers carpooling declined during the 1980s despite these efforts and subsequently research about carpooling waned.