Regional Action Plan the Role of Modal Interchange to Foster Low Carbon Urban Mobility
study was through the use of GIS, in which an end-to-end walking and cycling network was created from the polylines (street network) and points (location of facilities) collected for the study. The package used in this study was the Network Analyst extension within the Esri ArcGIS package.
to calculate the number of people resident or employed within the catchment. The latter is conducted by using the catchment areas to clip 2016 Census data for Small Areas and Workplace Zones, available from the Central Statistics Office. The catchment analysis will indicate areas of a town which are not within the catchment of facilities despite being close ‘as the crow flies’. These are areas where it is possible to improve accessibility by adding new links. Polylines representing these links can be added to the streetnetwork, andanewroutablenetworkcan be created. The process can then be repeated to assess how the catchment of facilities improves with the addition of new links.
5. Building a routable network
The routable network defines where it is possible to travel (indicated by the polylines representing streets), where it is possible to move between streets (indicated by the nodes where streets intersect), and how fast it is possible to move through the network (by defining an average speed for walking and cycling). Once these parameters are defined, the GIS package will be able to determine both the range that can be traversed and the time taken to do so within the extent of the network. Given that this is a pedestrian and cycle study, it is important to remove roads on which pedestrians and cyclists are not permitted (such as motorways) before creating the routable network. It is also possible to include public transport accessibility in the routable network using timetable information in General Transit Feed Specification (GTFS) format, which is useful for locations with frequent public transport services.
6. Running the catchment analysis
Once the routable network has been created, the catchment analysis of facilities in the given town can be conducted. The points representing the facilities of interest are defined, and then the parameters for the catchment analysis are specified, such as the time intervals (5 and 10 minutes in this case) and the modes (walking and cycling). The analysis is then run, determining which areas can be accessed from one or more facilities within the given time interval by the given mode, and polygons representing the catchment are produced. These can then be inserted into maps for visualisation or used
Southern Regional Assembly | Regional Action Plan
42
Made with FlippingBook flipbook maker