Operationalizing a spatial differentiation of trip generation rates using proxy indicators of accessibility

Based on a synopsis of the relevant literature, this contribution documents a recent empirical study of the accessibility - trip generation dependency, conducted with Germany's all-embracing MiD household survey data set of the year 2008. The analysis is motivated by a further development of the German National Transportation Model to include effects of accessibility on trip rates within the model part of trip generation. Ensuing from the national data protection legislation, the investigation cannot use geocoded trip origin and destination data, but needs to rely on reliable secondary data sources. The study sets out to address trip generation rates versus the spatial environment, using two proxy indicators of accessibility in a four-way approach: Linear models are complemented with the descriptive analysis of sample means and effect sizes, and a discrete trip frequency choice onset. Selected explanatory variables of the personal trip rates of more than 60 k respondents, with emphasis on home-based work and shopping trips, are systematized. The results lead to the conclusion that spatial connectivity of the household location has a relatively small impact on personal trip rates, as compared to socio-demographic and socio-economic household characteristics. Secondly, our findings support the assumption that significant spatial effects still occur for substitutable activities and their consideration in travel demand models could improve results.