1. MEASURING ACCESSIBILITY USING GIS MEASURING ACCESSIBILITY USING GIS Rui Pedro Julião Department of Geography and Regional Planning New University of Lisbon GeoComputation‘99

2. INTRODUCTION Accessibility is a key issue Traditional evaluation methods don’t consider a real spatial model Arc/Node logic versus Territorial logic Accessibility measurement Methodology Lisbon and Tagus Valley Region

3. STARTING ISSUES Graph Theory - Vector model Continuous surface - Raster model Geometry versus Analysis 3-step methodology: 1 - Data Acquisition and Integration 2 - Cost Surface Modelling 3 - Accessibility Analysis

4. DATA ACQUISITION AND INTEGRATION Geographical information Line weeding Reclassification Road CategoryLevel IP highway41 IP 2 lane21 IC highway42 IC 2 lane22 National Road23 Regional Road24 Municipal Road (former national) 25 Municipal Road26

5. COST SURFACE MODELLING CCT – Cell Crossing Time (min) P – Pixel Size (m) TS – Travelling Speed (Km/h) Considering a 2-lane IP: 6 Km/h outside the road network CCT = 1 minute RoadAverageCell Crossing CategorySpeedTime CategorySpeedTime (min) IP highway1100.0545 IP 2 lane800.0750 IC highway1100.0545 IC 2 lane700.0857 National Road600.1000 Regional Road550.1091 Municipal Road (former national)500.1200 Municipal Road500.1200 Off-road61.0000 2 cost surfaces: 2 cost surfaces: –With highways –Without highways

6. ACCESSIBILITY ANALYSIS COST SURFACE ORIGIN COST DISTANCE FUNCTION ACCESSIBILITY SURFACE ALLOCATION

7. ACCESSIBILITY TO THE HEAD OF MUNICIPALITY Cost surface calculation without considering the highway network.

8. ANALYSIS WORKFLOW Accessibility to head of municipality and territorial allocation based on a cost surface calculation without considering the highway network

9. TERRITORIAL ALLOCATION Which territory should belong to each municipality according to accessibility measurement

10. ACCESSIBILITY TO HIGHWAY NODES

11. ACCESSIBILITY TO LISBON Considering highways and the other road network

12. ANALYSIS WORKFLOW 3-Step calculation: a) estimate the travelling time to each highway node; b) estimate the travelling time and territorial allocation for each highway node; c) add the travelling time from Lisbon to the node to its hinterland’s travelling time + evaluation of alternatives

13. CONCLUSIONS Accessibility as key issue for many different studies n Methodological basis for accessibility measurement n GIS enables a full and dynamic territorial coverage n Future developments:Traffic data / Vehicle data Barriers Urban network data Population density Land use / Land cover