Assessing Car Dependence: Development of a Comprehensive Survey Approach Based on the Concept of a Travel Skeleton

Different concepts and definitions of car dependence were used in the past but none of these approaches combines subjective and objective dimensions. Based on the idea of a two-dimensional car dependence, we defined the objective (i.e., an individual needs a car to cope with daily activities) and subjective (i.e., an individual attributes other aspects to a car than the mobility) dimension to identify car dependence. For this purpose, we developed an integrated survey design that allowed us to collect information about the travel behavior and the sociodemographics of the participants as well as psychological constructs, e.g. attitudes and social norms, amongst others. To survey the travel behavior the participants had to report their behavior in a typical week in order to capture their usual mobility pattern and its determinants. There were questions about the frequency and locations of peoples’ activities, segmented for different purposes, which serves altogether as a “skeleton”. This travel skeleton is a reasonable compromise between the level of detail needed and the required effort to survey travel behavior. To capture the psychological dimension, we used a standardized item set with 27 questions (Hunecke et al. 2010). To define differing types of car dependence in order to classify people by their travel behavior and psychological factors, we used the data from an international survey undertaken in Berlin (Germany), San Francisco (USA) and Shanghai (China). The results demonstrated the feasibility of the survey approach and we were able to identify dissonances by persons between the subjective and objective dimensions. The findings also showed that persons from San Francisco are more objectively dependent on cars as persons from Berlin or Shanghai.

Sascha von Behren, Karlsruhe Institute of Technology