Development and implementation of spatial accessibility methods for the region of Västra Götaland (Sweden)
Quantitative methods for calculating spatial accessibility play an increasingly important role in the integrated assessment of transport and settlement systems
To design cities and regions that are attractive for the population, the connection of the places of residence to those places where activities such as working, education, shopping or entertainment take place is a central component of transport systems. In terms of sustainable mobility, it is important to be able to perform quantitative assessments of mobility for different modes of transport (walking, cycling, public transport, motorised private transport) to derive appropriate planning decisions. In recent years, the concept of spatial accessibility has become established for assessing how well, for example, shopping centres, schools, recreational areas, or health care facilities are accessible to the population. It provides an integrated framework for evaluating both the settlement planning and transport aspects of a system and for comparing different development scenarios.
The Västra Götaland region in south-west Sweden is pursuing very similar goals as part of a larger project in cooperation with the University of Gothenburg. The project content can be roughly summarised as follows: In a first step, methods are to be developed to determine spatial accessibility for municipalities as well as for the entire region. The focus will be on questions from the areas of transport, housing, work, and social aspect. In a second step, instruments (GIS-based tools, R-code) are to be developed to support regional planning. In addition to the development of methods and tools, this project also aims to explicitly promote cooperation between regional planning practice and academia.
Within a sub-project, methods for spatial accessibility were developed and implemented by the IDP. In addition to the methodological objectives, freely available geodata (as far as possible) and open-source software tools were used. Specific data on population and jobs were provided by the client Västtrafik (Västra Götaland County Transport Authority) and other public bodies.
The application of the implementation in case studies initially focused on the accessibility of workplaces by public transport, working with a grid size of one square kilometre for the population distribution. Other activity classes (education, shopping, etc.) and spatial resolutions could be selected as well.
In this project, various methods with corresponding measures were developed. A relatively simple but easily communicable measure is the total number of jobs that can be reached within a certain time. Hence, the travel times for all inhabited places to the corresponding workplaces must be calculated first. An example of a map showing the minimum travel times to the six major centres in the region was prepared for the years 2014 (reference, last survey) and 2018 (see figure above) and was included in the 2018 annual report of the transport authority, together with various aggregated figures on the changes between the two years.
In addition to the development and implementation of the calculation methods in the programming language R, a one-day workshop (presentation of the project results; practical training on the computer with specific calculation examples in R) was held in Gothenburg as another part of the project. Twenty people from different planning areas of the City of Gothenburg, the region, universities, and consultancies participated. In addition to communicating the project results, the event also aimed to enable participants to get to know the new methods and tools and to try them out themselves, and to promote cooperation between the institutions.