UC Davis Institute of Transportation Studies

The relationship between telecommunications and travel has been a fertile area of research for several decades. Early speculation (e.g., Owen, 1962) focused on the potential of telecommunications to replace travel. That hope eventually led to the establishment of several telecommuting programs, and empirical evaluations of those programs (e.g., Hamer, et al., 1991; Mokhtarian, et al., 1995) seemed to support the substitution expectation. While empirical evidence for other telecommunications applications was far more scarce, it was similarly expected that teleconferencing, teleshopping, distance learning, and other such services would also replace travel. In the meantime, however, some scholars (e.g. Albertson, 1977; Salomon, 1985; Mokhtarian, 1990, 2003; Niles, 1994) began to point out that substitution was not the only possible impact of telecommunications on transportation. In particular, it was argued that a very likely impact would be the generation of more travel, or complementarity. In the short term, this effect could arise in two kinds of ways, which the literature (Salomon, 1986) labels enhancement and efficiency.

* Enhancement refers to a direct impact of one mode of communications (e.g. telecommunications) on the demand for another mode (e.g. travel). For example, the increasing ease of electronically obtaining information about interesting locations, activities, and people could stimulate the demand for travel to visit those locations or people and engage in those activities (Gottman, 1983; Couclelis, 1999). * Efficiency refers to the use of one mode (e.g. telecommunications) to improve the operation of another mode (e.g. the transportation network). The effect on demand is indirect in this case, by increasing the effective supply of transportation and hence, by lowering its (generalized) cost, making travel more attractive and thus increasing the demand for it.