1. Arizona State University
Using GIS to Generate Mutually Exclusive Service Areas Linking Travel On and Off a Network
Christopher Upchurch
Michael Kuby
Michaek Zoldak
Anthony Barranda
Arizona State University

2. Light Rail Research Station Area Factors Service Area Requirements
Walking Distance
Mutually Exclusive
Network Based

3. Available Buffering Techniques
Euclidian Buffers
Circular

4. Circular Buffers

5. Available Buffering Techniques
Euclidian Buffers
Circular
Thiessen Polygon

6. Thiessen Polygon Buffers

7. Available Buffering Techniques
Euclidian Buffers
Circular
Thiessen Polygon
Combined Circular and Thiessen Polygon

8. Combined Circular and Thiessen Polygon Buffers

9. Available Buffering Techniques
Euclidian Buffers
Circular
Thiessen Polygon
Combined Circular and Thiessen Polygon
Network Based Buffers
ArcView Network Analyst

10. ArcView Network Analyst Service Areas

11. ArcView Network Analyst Service Areas

12. ArcView Network Analyst Service Areas

13. Available Buffering Techniques
Euclidian Buffers
Circular
Thiessen Polygon
Combined Circular and Thiessen Polygon
Network Based Buffers
ArcView Network Analyst
ArcView Network Analyst + Thiessen Polygon

14. Service Area Requirements
Walking Distance
Mutually Exclusive
Network Based

15. LOON Method Linked On-Off Network Method Raster Based
Hierarchical Approach
Distance Off the Network
Distance On the Network

16. Step 1: Initialization Network Impedance Grid Source Grid
Off-Network Impedance Grid

17. Network Impedance Grid

18. Source Grid

19. Off-Network Impedance Grid

20. Step 2: Calculate Lowest Network Distance
Cost Distance Command
Finds:
Closest Source Node for Each Cell
Distance to that Source Node
Using:
Source Grid
Network Impedance Grid
Output:
Raw Distance Grid
Allocation to Source Node Grid

21. Raw Distance Grid

22. Allocation to Source Node Grid

23. Step 3: Create a New Set of Source Cells
Hierarchical Approach
Distance On the Network
Distance Off the Network
New Source Cells for Second Cost Distance Command

24. Raw Distance Grid

25. All-Network Source Grid

26. Step 4: Calculate Off-Network Distance
Cost Distance Command
Using:
All-Network Source Grid
Off-Network Impedance Grid
Output:
Off-Network Distance Grid
On-Network Distance Grid

27. Off-Network Distance Grid

28. On-Network Distance Grid

29. Step 5: Calculate Total Distance
Off-Network Distance +
On-Network Distance

30. Total Distance Grid

31. Step 6: Trim and Reclassify the Total Distance Grid
Reclassify all cells less than maximum distance as 1
Reclassify all cells more than maximum distance as “no data”

32. Buffer Mask Grid

33. Step 7: Create Final Buffers
Buffer Grid =
Allocation to Source Node Grid x
Buffer Mask Grid

34. Buffer Grid

35. Proof of Concept
What Benefits does the LOON method have over other techniques for generating service areas?

36. LOON Service Areas

37. LOON vs. Circular + Thiessen

38. LOON vs. ArcView + Thiessen

39. Statistical Comparisons ArcView vs. LOON
Employment of Sacramento buffers calculated using both methods
Citywide average area and employment fairly close, within 5%
Average percentage difference greater than 85%

40. Questions? Step by Step Instructions are available at:
Questions?