Advances in the Measurement of Transport Impedance in Accessibility Modelling
Accessibility is a key concept in both transport and urban planning. The key aims of transport policies, not only at the urban level but also at the supra-national (for example, European Union), national and regional level, are to improve accessibility. Accessibility is also a key concept that has become central to physical planning and in spatial modelling for more than fifty years. As measure of the relative nearness or proximity of one place and persons to all other places or persons, conceptually linked to Newton’s law of gravity, its origins can be traced back to the 1920s when it was used in location theory and regional economic planning (Batty, 2009). In his classic paper ‘How Accessibility Shapes Land Use’, Hansen (1959) was the first to define accessibility as a potential of opportunities for interaction and applied the concept to forecast employment developments in Washington D.C.. Accessibility is thus a key concept in planning and research but often a confusing one. Many different accessibility definitions and operationalisations in accessibility models and instruments have in the past decades been developed and applied by researchers from several academic fields (e.g., urban geography, rural geography, health geography, time geography, spatial economics, transport engineering) and transport and urban planners (e.g., see for reviews Geurs and van Wee, 2004; Páez et al., 2012; Papa et al., 2016).