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

Abstract

Although many models/tools have recently been developed to measure spatial accessibility, many of these tools are still restricted to academic studies and have barely been applied in the world of planning practice due to several reasons including the complexity or inadequacy of the methodological approaches involved. Within this context, the research undertaken is motivated by the need to translate the concept of accessibility into a practical and useful tool for practitioners and policy makers. The research identifies several omissions in existing accessibility tools that can be considered as potentially important limitations for some purposes in transport and land-use planning. It also investigates the key features that characterise the usefulness of accessibility tools in planning practice. These findings have been used to develop the GIS-based accessibility tool for this research – SNAPTA (Spatial Network Analysis of Public Transport Accessibility) – which attempts to offer better usability and responds to a number of the omissions identified in existing accessibility tools. SNAPTA has been applied to a pilot study in Edinburgh city with the main aim of analysing the contribution of the planned transport interventions to improved accessibility by public transport and distributional benefits for urban services and activities in the city. This research case study presents the first attempt to analyse profoundly the accessibility impacts of possible combinations of implementing future phases of the Edinburgh Tram and the Edinburgh South Suburban Railway (ESSR). The findings provide a better insight into the spatial equity and accessibility levels in Edinburgh, demonstrating the significance of introducing non-radial public transport routes to the city network. A key output of the analysis suggests that the first part of Edinburgh Tram, delivered in summer 2014, would bring a very limited improvement to the accessibility of population across Edinburgh Council‟s area. On the other hand, the empirical evidence of the study shows that ESSR can play a significant role, bringing a greater benefit for accessibility than any other combination of tram lines. A workshop organised to test SNAPTA in a virtually real exercise enabled expert assessment of the usefulness, robustness and applicability of the tool. The research concludes that SNAPTA offers a useful alternative that can be used in decision-making to inform strategic planning processes for future urban growth and urban structure framed around the integration of land-use with strong public transport accessibility.