Abstract:Unfortunately, there has been no commonly accepted definition of the term "life-style" in the field of travel behavior analysis and demand forecasting. Little empirical evidence exists on how an individual acquires a particular life-style, how it is correlated with measurable attributes of the individual and his household, and how it is related to travel behavior. Nevertheless, the life-style concept extends the scope of travel behavior analysis and may possibly lead to improved predictive performance of forecasting models. For example, a recent analysis of trip generation behavior using longitudinal observations finds that there is an unexplained individual-specific effect, or idiosyncrasy. This idiosyncrasy, which is not explainable by sociodemographic variables, can be viewed as arising from the life-style of the individual.

The term "life-style" as used in the literature has two meanings: (a) activity and time-use patterns and (b) values and behavioral orientation. These two are interrelated, but a critical difference exists: life-style as activity patterns may change as an individual adapts to a change in the environment, whereas lifestyle as orientation is one that the individual attempts to maintain by modifying behavioral patterns and adapting to the change. Change in life-style as orientation takes place in the long term through changes in values, attitudes, and preferences.

Life-style changes with socioeconomic, institutional, and technological changes. Increasing real income, decreasing working hours, and new consumer technology all contribute to the ever-evolving life-style of urban residents. The seemingly ever-expanding consumer demand leads to new products and services, industries and institutions, and urban forms. To gain an understanding of life-style and to develop the capability to predict its changes in the future, it is necessary to examine changes that took place in various elements of urban life and see how these changes are related to changes in life-style and travel behavior. This will constitute a basis for a more fundamental approach to long-range travel demand forecasting.

The objectives of this paper are (a) to offer a review of the monetary expenditure and travel characteristics of households across population subgroups defined in terms of variables believed to be correlated with life-style, (b) to determine the usefulness of this body of knowledge in long-term forecasting of travel demand, and (c) to identify factors that may influence life-style and travel behavior but that have not been incorporated into travel behavior analysis and demand forecasting.

The paper is organized as follows. The definitions of life-style found in the literature are reviewed in the next section and variables that have commonly been associated with life-style are identified. Then the life-styles of population segments are reviewed using consumer expenditure statistics. The findings in the literature on travel characteristics of these segments are summarized; trends in the variables associated with life-style are reviewed, and likely changes in travel behavior are noted using the travel characteristics identified earlier. The discussion is extended to include those contributing factors that are typically not considered in travel behavior analysis. The last section presents conclusions and recommendations.