Accessibility modelling: predicting the impact of planned transport infrastructure on accessibility patterns in Edinburgh, UK

• We assess the accessibility impact of changes in public transport provision within Edinburgh Council’s area.
• The developed model responds to several limitations in existing models in planning practice.
• Limited improvement brought by the tram and ESSR to accessibility to jobs in Edinburgh.

The achievement of good spatial accessibility and equity in the distribution of urban services is one of the supreme goals for urban planners. With Scottish Government backing, the City of Edinburgh Council (CEC) has started to construct a tram network to cater for the future needs of Scotland’s capital city by providing an integrated transport solution using trams and buses. Spatial Network Analysis of Public Transport Accessibility (SNAPTA) which is a GIS-based accessibility model has been developed to measure the accessibility by public transport to different urban services and activities. The model responds to several limitations in other existing accessibility models in planning practice. It offers an alternative and practical tool to help planners and decision makers in examining the strengths and weaknesses of land use – transport integration. SNAPTA has been applied to a pilot study in Edinburgh city to identify the contribution of the infrastructure improvements of the tram system and Edinburgh South Suburban Railway (ESSR) to improved accessibility by public transport to six types of activity opportunities. This paper outlines the concept and methodology of the SNAPTA model, and presents the findings related to this pilot study with a focus on changes in potential accessibility to jobs between four different public transport network scenarios. The accessibility values so obtained help to identify the gaps in the coverage of the public transport network and the efficiency in the spatial distribution of urban services and activities. The findings focus on whether the planned transport infrastructures for Edinburgh will lead to better accessibility and reduced inequity (in terms of accessibility) across the city.