Mobility tools and use: Accessibility’s role in Switzerland

In much of Switzerland, public transport offers high levels of accessibility to workplaces and other places that make season tickets legitimate substitutes for a car. These similar patterns of accessibility provided by both modes result in high levels of correlation between the accessibility measures of both modes. This correlation almost always precludes a travel behavior analysis with several accessibility measures and cannot provide any insights into the effects of the differences in accessibility levels by both modes. We propose a principal component analysis of the accessibility measures to extract as much information as possible. We interpret the principal components obtained as: general accessibility, comparatively better accessibility by public transport and comparatively better job accessibility. The new accessibility variables are used in a model of car and season ticket ownership and the number of car, public transport and non-motorized trips using data from the 2010 Swiss transportation microcensus. These outcomes are jointly estimated with a probit-based model for mixed types of outcomes because we anticipated simultaneous choices and that choices are dependent on each other. We found that greater levels of general accessibility, comparatively better accessibility by public transport and comparatively better job accessibility increased the probability of season ticket ownership, while the probability of car ownership decreased. We realize that ownership and use must be jointly modeled to consistently estimate the structural effects of mobility tool ownership on use.