Differences in levels of accessibility

The importance of spatial scale when measuring distributions of the accessibility of health and emergency services

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This paper explores to what extent inequalities in travel times, measured via the Gini index, depend on the spatial scale at which (average) travel times are measured. By using the new concept of Dedicated Accessibility Points, for the Netherlands we calculated average travel times at four spatial levels, ranging from virtually individual addresses to the level of municipalities. Travel times by car and bicycle to three medical points of interest are calculated: pharmacies, family doctors, and hospitals, as well as travel times by car from three other points of interest: ambulance stations, fire stations and police stations. At the level of individual addresses the errors made due to spatial aggregation is absent, but at higher spatial scales it plays a role. The results show that the Gini index is heavily influenced by the spatial scale at which the indices are calculated, with smaller indices at higher spatial scales. We discuss the implications of these differences for research and policy.