Establishing a Common Geospatial Approach to Public Transport Service Area Analysis

Previous studies (Harrison & O’Connor, ITRN 2012; O’Connor (2), ITRN 2014) have analysed the walking catchment area for bus, light rail and metropolitan rail stops in suburban parts of Dublin city. Public transport users were sampled at each stop and their absolute trip origin identified. This information was then used to identify and approximate the catchment area for public transport at that location. The purpose of this paper is to collate existing information and establish a common appraisal format using geospatial analysis. Specifically, data from earlier studies will be fed into a geodatabase design and a spatial analytical framework developed for use with ArcMAP 10.2. This will require geo-referencing of all trip-origins using ArcMAP and coding of each origin-point by mode of travel to/from public transport services. Catchment areas can then be identified using the ArcMAP Network Analyst function. It may be necessary, for example, to distinguish between (i) the core pedestrian catchment and (ii) the extended catchment (affected by range extenders such as cycling, kiss & ride and local feeder services, etc.). Path files will need to be validated against the actual network to eliminate coding, geometric and informal path errors. A common geospatial approach should yield a more precise measure of the actual extent of public transport catchments across a range of contrasting locations. It should also provide a more robust template for further data capture, a key recommendation of earlier studies