Dawn Wright and Jim Graham

1. Network Analysis, Routing Dawn Wright and Jim Graham

2. Optimization • Spatial analysis can be used to solve many problems of design • A spatial decision support system (SDSS) is an adaptation of GIS aimed at solving a particular design problem

3. Networks • Systems of connected lines • Weights along edges Junctions Edges

4. Examples • Electrical Grid • Power lines and transfer stations • Roadways (highways, freeways) • Roads and intersections • Pipelines • Canals, streams, rivers • Shipping lanes

5. Example: Freeways

6. Network Rules • Edge-Junction: • Which edges can connect to a junction • Examples: • Three-phase 240 volt vs. high voltage • Freeway to overpass • Edge-Edge: • Freeway to Freeway: overpass with clover leaf • Freeway to Highway: overpass with lights • Highway to Highway: lights • Road to Road: stop signs

7. Weights • Edge • Type of surface, speed limit -> Travel time • Junction • Type of intersection -> stop time • Barrier • Stops travel, can be temporal • Examples: • Construction • Raising bridges

8. Sources & Sinks • Sources • Add to the network • Examples: • Downtown at 5:00pm • Tunnels • Bridges • Sinks • Terminate a network • Examples: • Suburbs at 5:00pm • Tunnels

9. Lab 5 • Edges, junctions, and weights

10. Lab 5

11. Network Problems • Shortest path: Route • Minimizing total distance traveled • Minimizing the largest distance traveled by any customer • Maximizing profit • Minimizing a combination of travel distance and facility operating cost

12. Network Analyst • Finding Optimal Routes • Route Solver Properties • Service Area Solver Properties • Closest Facility Solver Properties • OD Cost Matrix Solver Properties • Vehicle Routing Problem Solver Properties • Location Allocation Solver Properties

13. Shortest Path - Route • Stops • Time windows for deliveries • Etc.

14. Closest facility analysis • Multiple origins, destinations, facilities along the route

15. OD Cost Matrix

16. Routing service technicians for Schindler Elevator. Every day this company’s service crews must visit a different set of locations in Los Angeles. GIS is used to partition the day’s workload among the crews and trucks (color coding) and to optimize the route to minimize time and cost.

17. Least-Cost Paths • Find the best path across a continuous surface • between defined origin and destination • to minimize total cost • cost may combine construction, environmental impact, land acquisition, and operating cost • used to locate highways, power lines, pipelines • requires a raster representation

18. Cost-Distance

19. Example: Santa Ynez Mtns., CA More details at http://www.ncgia.ucsb.edu/~ashton/demos/chuck95/stochastic.html Chuck Ehlschlaeger, Ashton Shortridge

20. Least-cost path problem. Range of solutions across a friction surface represented as a raster. The area is dominated by a mountain range, and cost is determined by elevation and slope.

21. Solution of the least-cost path problem. The white line represents the optimum solution, or path of least total cost. The best route uses a narrow pass through the range. The blue line results from solving the same problem using a 90-m DEM.

22. Least Cost Path

23. Minimum Cost Path • Create a “Cost” raster • Each pixel contains the cost of “moving through” that pixel • Create a “Cost Distance” raster • Each pixel contains the least cost to move from that pixel to a destination (or from a source) • Create a “Cost Backlink” raster • Each pixel contains the direction to move to get to the destination (or source) with the least cost • Find the “Cost Path”

24. Cost Rasters • What is the cost of covering ground? • Slope • Surface type: Swamp vs. Highway • Others… • Distance to forage… • Distance to predator hide… • Cost to put a path across the pixel… • Cost of creating a path: • MinimumCost + Slope ^ Exponent

25. Cost Raster

26. Cost Distance

27. Straight Line Distance

28. Cost Distance

29. Backlink Raster

30. Least Cost Path

31. Least Cost Path

32. Cost-Distance • Least expensive trail, road, pipeline, power line, route, etc. • Migration routes? • Others?

33. Finding Viewsheds

34. View shed Parameters OFFSETA ArcGIS Help

35. Effect of “Offset A” Offset A=100 Offset A=0 (default)

36. Optimization & Routing for Emergency/Disaster Response • Kim et al. 2006 – PARs, Protective Action Recs d= interpolated, shortest-distance of wildfire to community d1 = shortest distance before PAR d2 = shortest distance after PAR t = time PAR was issued t1 = time last known fire perimeter at d1 t2 = time last known fire perimeter at d2

37. Fire Origin to Communities:Estimate Avg. Speed of Fire Between Known Perimeters Kim et al. 2006

38. Gateway to the Literature • Cova, T. and Johnson, J.P., 2002. Microsimulation of neighborhood evacuations in the urban-wildland interface. Environment and Planning A, 34: 2211-2229. • Cova, T. J., P. E. Dennison, et al. 2005. Setting wildfire evacuation trigger points using fire spread modeling and GIS. Transactions GIS, 9(4): 603-617. • Kim, T.H., Cova, T.J., and Brunelle, A., 2006. Exploratory map animation for post-event analysis of wildfire protective action recommendations. Natural Hazards Review, 7(1): 1-11. • Monteiro, C., Ramirez-Rosado, I., Zorzano-Santamaria, P. and Fernandez-Jimenez, L.A., 2005. GIS spatial analysis applied to electric line optimization. IEEE Transactions on Power Delivery, 20(2): 934-942.

39. (Extra slide) Cova et al. 2005