The Transportation Department responded to this mandate by extrapolating estimated travel substitution rates determined in small-scale demonstrations of telecommuting into projections of U.S. nationwide travel savings. US DOT estimated that savings over ten years would reduce total vehicle miles traveled by approximately one percent below what travel would be without telecommuting. This remarkably small number is likely to be insignificant on the roads of a growing urban area. Exactly where the amount of consumption of transportation and telecommunications nets out in an overall regional, national, or subnational economy depends logically on the perceived cost of using one mode versus the other. Price levels of transportation and telecommunications are of course heavily influenced by government policies toward telecommunications, energy, the environment, urban development, and other matters.
Cost includes both monetary price, as well as the cost in time, attention, and aggravation.
Being stuck in traffic congestion is an example of a cost of travel. Being frustrated by an electronic mail service that delivers too many junk messages, or waiting excessively for files to download from the Internet are costs of using telecommunications. The time it takes to learn to use new forms of telecommunications is a cost also. Telecommuting and telephone use surged in the days and weeks following the 1994 Los Angeles earthquake and the disruption of Southern California highways. This result illustrates that telecommunicating becomes more attractive when travel becomes relatively more costly.