1. EPRI Environmental Sector Meetings Optimal Routing and Corridor Analysis for Electric Transmission Line Siting Procedures for Infusing Stakeholder Perspective in Identifying Optimal Route Alternatives Joseph K. Berry University of Denver, Geography Christy Johnson Georgia Transmission Corporation Water & Ecosystem Area Council Meeting Boston, MA — September 29, 2004 In 2002, The Electrical Power Research Institute (EPRI) and Georgia Transmission Corporation (GTC) entered into a Tailored Collaboration Project to examine and refine GTC’s existing Overhead Electrical Transmission Line Siting Methodology. The scope of the project was to develop new transmission line siting tools, techniques and procedures for GTC that are objective, quantitative, predictable, consistent, and defensible and to prepare a Overhead Electrical Transmission Line Siting Methodology Report that explains and documents the process. Among the longer-term goals of this project is exploration of the prospects and opportunities of standardizing the decision process for overhead electrical transmission line siting for the electrical industry.

2. Presentation Topics  Understanding the Basic Routing Process  Identifying Optimal Route and Corridor  Generating Alternative Routes  Applying Process to Electric Transmission Line Routing  Macro Corridor Identification  Alternative Corridor Generation  Development of Alternative Routes within Alternative Corridors  Alternative Route Analysis  Selection of the Preferred Route

3. Simplified Example Criteria – the transmission line route should… Avoid areas of high housing density Avoid areas that are far from roads Avoid areas within or near sensitive areas Avoid areas of high visual exposure to houses Houses Roads Sensitive Areas Houses Elevation Goal – identify the best route for an electric transmission line that considers various criteria for minimizing adverse impacts. Existing Powerline Proposed Substation

4. Routing Model Flowchart (Model Logic) Model logic is captured in a flowchart where the boxes represent maps and lines identify processing steps leading to a spatial solution Far from Roads In or Near Sensitive Areas High Visual Exposure High Housing Density Avoid areas of… FactJudgment Levels of Abstraction

5. Routing Model Flowchart (Model Logic) Step 1 Identify overall Discrete Preference (1-9 rating) Step 1 Three sub models– 1) Discrete Preference, 2) Accumulated Preference and 3) Most Preferred Route Step 2 Generate an Accumulated Preference surface from the starting location to everywhere Step 2 Start Calibration Weighting Step 3 Identify the Most Preferred Route from the end location Step 3 End Start

6. Discrete Preference Surface (Step 1) HDensity RProximity SAreas VExposure Calibration Weighting

7. Accumulated Preference Surface (Step 2) Splash Algorithm – like tossing a stick into a pond with waves emanating out and accumulating costs as the wave front moves

8. Most Preferred Route (Step 3)

9. Identifying an Optimal Corridor (N th Best Routes)

10. Real World Application (Processing Schematic) B E N B E N (avg) B E N BuiltEngr.Natural Criteria 3) The categories on each Criteria Map are calibrated to a range of 1=best to 9= worst for siting a transmission line ExcludedStakeholderGroups 4) Relative importance weights for the Criteria Maps within each group are used to calculate an overall preference map Categories 2) Information that influence transmission line siting are identified 1) Locations that prohibit siting are eliminated from consideration Exclusions Slope Hydro- graphy Flood- plane Public Lands Existing Utilities Trans- poration Land Cover Proximity Excluded Proximity Buildings etc. Building Density Visual Exposure Proximity Schools Weighting Calibration Simulations 5) The best route and corridor is determined for conditions favoring each group’s perspective and one where all are equally weighted– Four alternative routes reflecting different perspectives

11. Real World Application (Results) Weighting one stakeholder group over the others derives alternative routes that emphasize their particular concerns Combining alternative corridors identifies the decision space reflecting various perspectives …routing decision space

12. Model Calibration and Weighting Avoid areas of… High Housing Density Far from Roads In or Near Sensitive Areas High Visual Exposure …but what is “high” housing density and how important is it? Ratings– relative preference among categories within a single map layer Weights– relative preference among map layers

13. Calibrating Map Layers (Delphi) Model calibration refers to establishing a consistent scale from 1 (most preferred) to 9 (least preferred) for rating each map layer… The Delphi Process is used to achieve consensus among group participants. It is a structured method involving iterative use of anonymous questionnaires and controlled feedback with statistical aggregation of group response. 1 for 0 to 5 houses …group consensus is that low housing density is most preferred Fact Judgment (See www.innovativegis.com/basis, select Column Supplements, Beyond Mapping, September 03, Delphi)

14. Delphi Process (Spreadsheet) …the process is repeated until there is “acceptable” consensus on the calibration ratings Each participant identifies their cut-off values 1=good to 9= bad (avoid) Summary statistics are computed and used to stimulate discussion about differences in opinions Information on each data layer is presented and discussed by the group …structured method involving iterative use of anonymous questionnaires and controlled feedback

15. Weighting Map Layers (AHP) Model weighting establishes the relative importance among map layers (model criteria) on a multiplicative scale… The Analytical Hierarchy Process (AHP) establishes relative importance among by mathematically summarizing paired comparisons of map layers’ importance. HD * 10.38 R * 3.23 SA * 1.00 VE * 10.64 …group consensus is that housing density is very important (10.38 times more important than sensitive areas) (See www.innovativegis.com/basis, select Column Supplements, Beyond Mapping, September 03, AHP)

16. Calculating the Relative Weights (Expert Systems) Each participant completes questions comparing the relative importance of the data layers-- “…avoiding locations of high visual exposure is _____ more important than avoiding areas close to sensitive areas” 1=same to 9= extremely more important Responses are entered into the pairwise comparison matrix and it is solved for the relative weight of each map layer …statistics for logical consistency and degree of agreement are used to determine consensus …establishes relative importance among by mathematically summarizing paired comparisons of map layers’ importance

17. Summary of the Basic Routing Process A quantitative process for establishing objective and consistent weights is critical in developing a robust and defendable transmission line siting methodology. The Delphi and Analytic Hierarchical Process (AHP) are well- established technologies for leveraging expertise and collective wisdom that assist in establishing siting preferences. Theses advanced procedures are used to logically organize suitability problems and derive a set of consistent ratings and weights by systematically structuring stakeholder group input. GIS-based approaches for siting electric transmission lines utilize relative ratings and weights in considering factors affecting potential routes. The calibration and weighting of numerous factors, such as housing density, visual exposure and proximity to roads and sensitive areas are established for each grid cell location, and then analyzed for the overall “least cost path” (LPC) …optimal route. In practice, the weight set is altered to identify a set of alternative optimal corridors and routes for consideration. …the result is a routing procedure that is objective, quantitative, predictable, consistent, and defensible

18. Presentation Topics  Understanding the Basic Routing Process  Identifying Optimal Route and Corridor  Generating Alternative Routes  Applying Process to Electric Transmission Line Routing  Macro Corridor Identification  Alternative Corridor Generation  Development of Alternative Routes within Alternative Corridors  Alternative Route Analysis  Selection of the Preferred Route

19. Corridor Analysis Funnel Overview of Methodology

20. Macro Corridor Identification  Using Geographic Information Systems (GIS), a high level analysis of the project area is performed to identify Macro Corridors.  Macro Corridors are generated using land use/land cover data from 30 meter satellite imagery and existing statewide GIS datasets.  Macro Corridors are areas of least impact to communities and the environment. These Corridors are used to define the outer boundaries of the project study area. Identifying Macro Corridor (Project Area Extents)

21. …composite of several data layers— land cover, roads and existing transmission lines Macro Corridor GIS Database

22. Macro Corridors are used to define the project study area for further data collection, which is site-specific, more detailed, and at a higher resolution. By focusing data collection on the Macro Corridors time, money, and effort are saved. Data Collection Area

23. Presentation Topics  Understanding the Basic Routing Process  Identifying Optimal Route and Corridor  Generating Alternative Routes  Applying Process to Electric Transmission Line Routing  Macro Corridor Identification  Alternative Corridor Generation  Development of Alternative Routes within Alternative Corridors  Alternative Route Analysis  Selection of the Preferred Route

24. Alternative Corridors are generated within the Macro Corridors. These Alternative Corridors are modeled using criteria that produce a standardized set of alternatives.  Built Environment Perspective Protecting people places and cultural resources  Engineering Requirements Perspective Minimizing costs and schedule delays  Natural Environment Perspective Protecting water resources, plants and animals  Simple Average Perspective A composite of the Built, Natural and Engineering Perspective Alternative Corridor Generation

25. Alternative Corridor Model Structure Avoidance Areas Criteria Layers Perspectives

26. Floodplain (6%) Streams/Wetlands (21%) Public Lands (16%) Land Cover (21%) T&E Species Habitat (36%) Natural Environment Wt. Average Natural Alternative Corridor Model Avoided Areas Routing Criteria: Engineering Natural Built Overall Preference Surface Combined Avoidance Areas Buildings + Buffer Special Places Sensitive Areas Physical Barriers Discrete Preference Surface Can’t go there… Avoid if possible… Alternative Corridor Criteria and Weights Wt. Average CRITERIA (1) Wt. Average Built Built Environment Proximity Buildings (12%) NRHP Historic (14%) Building Density (37%) Proposed Development (6%) Spannable Waterbodies (4%) Land Use (19%) Perspectives Wt. Average Engineering Engineering Requirements Linear Infrastructure (48%) Slope (9%) Intensive Ag (43%) Layers

27. Avoidance Areas Avoidance Areas Non – Spannable Water bodies Church Parcels State and National Parks Airports Wild and Scenic Rivers Cemetery Parcels City and County Parks Wildlife Refuge Ritual Importance School Parcels EPA Superfund Sites Military Facilities Building + Buffers Daycare Parcels Mines and Quarries NRHP Historic Sites NRHP Historic Districts NRHP Archaeology Sites NRHP Archaeology Districts USFS Wilderness Area

28. Built Environment Eligible NRHP Historic Structures Background 1500’ Buffer Major Property Lines Landlots Edge of Field Background Proposed Development Proposed Development Background Spannable Lakes And Ponds Spannable Lakes and Ponds Background 0 – 300’ Proximity to Buildings Background 600 – 900’ 300 – 600’ 900 – 1200’ Land Use Residential Non- Residential Other Built Environment Perspective Building Density 4 – 25 Buildings/ Acre 0.05 – 0.2 Buildings/ Acre 0.2 – 1 Buildings/ Acre 0 – 0.05 Buildings/ Acre 1 – 4 Buildings/ Acre

29. Natural Environment Floodplain 100 Year Floodplain Background Public Lands WMA – State Owned WMA – Non-State Owned Other Conservation Land Background USFS Streams/ Wetlands Trout Streams + Reg. Buffer Streams < 5cfs + Reg. Buffer Rivers/Streams  5cfs + Reg. Buffer Non-Forested Wetlands + Reg. Buffer Non-Forested Coastal Wetlands + Reg. Buffer Background Forested Wetlands + Reg. Buffer Managed Pine Plantations Land Cover Row Crops And Horticulture Developed Land Hardwood And Mixed Forest Open Land Wildlife Habitat Natural Areas Species of Concern Habitat Background Natural Environment Perspective

30. Engineering Linear Infrastructure Slope Intensive Agriculture Background Center Pivot Irrigation Slope 0–15% Slope 15-30% Slope > 30% Parallel Existing T/L Parallel Road ROW Parallel Railroad ROW Parallel Interstate ROW Road ROW Scenic Highway ROW Future GDOT Plans Rebuild Existing T/L Parallel Gas Pipeline Background Fruit Orchards Pecan Orchards Engineering Requirements Perspective

31. Calibrating Criteria:  Use Delphi Process  Rate each category of from 1 (best) to 9 (worst) Weighting Layers:  Use Analytical Hierarchy Process  Pairwise Comparison Calibrating Criteria and Weighting Layers Layers Criteria Delphi Form AHP Form Group Interaction

32. Criteria Ratings and Map Weights

33. Presentation Topics  Understanding the Basic Routing Process  Identifying Optimal Route and Corridor  Generating Alternative Routes  Applying Process to Electric Transmission Line Routing  Macro Corridor Identification  Alternative Corridor Generation  Development of Alternative Routes within Alternative Corridors  Alternative Route Analysis  Selection of the Preferred Route

34. The Alternative Corridors are the top 3% of the best routes within the Macro Corridors. Alternative Corridor Generation …recall the “flooding” technique using the combined Start and End accumulation surfaces to derive optimal corridors

35. Additional detailed data is gathered within the Alternative Corridors. Alternative Route Development

36. Within each of the Alternative Corridors, the Siting Team develops Alternative Routes.

37. Developing Alternative Routes Less Suitable More Suitable Standardized Alternative Routes Built Natural Engineering Simple

38. Presentation Topics  Understanding the Basic Routing Process  Identifying Optimal Route and Corridor  Generating Alternative Routes  Applying Process to Electric Transmission Line Routing  Macro Corridor Identification  Alternative Corridor Generation  Development of Alternative Routes within Alternative Corridors  Alternative Route Analysis  Selection of the Preferred Route

39. Alternative Route Evaluation  Evaluate Alternative Routes using data summarizing:  Built Environment  Natural Environment  Engineering Requirements  Compare Alternative Routes  Select Preferred Route

40. Alternative Route Analysis ROUTE AROUTE B FARMLAND 54% COMMERCIAL 23% INDUSTRIAL 6% RESIDENTIAL 12% FORESTS 21% FARMLAND 30% RESIDENTIAL 29% COMMERCIAL 26% INSTITUTIONAL 5% INDUSTRIAL 10%

41. Evaluating Alternative Routes

42. Presentation Topics  Understanding the Basic Routing Process  Identifying Optimal Route and Corridor  Generating Alternative Routes  Applying Process to Electric Transmission Line Routing  Macro Corridor Identification  Alternative Corridor Generation  Development of Alternative Routes within Alternative Corridors  Alternative Route Analysis  Selection of the Preferred Route

43. Alternative Route Statistics …the relative merits of top few routes based on the alternative route evaluation information are discussed by the siting team then ranked to identify the best route.

44. Conclusions and Discussion In 2002, The Electrical Power Research Institute (EPRI) and Georgia Transmission Corporation (GTC) entered into a Tailored Collaboration Project to examine and refine GTC’s existing Overhead Electrical Transmission Line Siting Methodology. The scope of the project was to develop new transmission line siting tools, techniques and procedures for GTC that are objective, quantitative, predictable, consistent, and defensible and to prepare a Overhead Electrical Transmission Line Siting Methodology Report that explains and documents the process. Among the longer-term goals of this project is exploration of the prospects and opportunities of standardizing the decision process for overhead electrical transmission line siting for the electrical industry. Joseph K. Berry University of Denver, Geography jkberry@du.edu Christy Johnson Georgia Transmission Corporation christy.johnson@gatrans.com

45. Further Reference This PowerPoint is posted at… http://www.innovativegis.com/basis/EPRI_GTC/ Online Papers GeoWorld magazine feature article on the EPRI_GTC project… http://www.geoplace.com/gw/2004/0404/0404pwr.asp GeoTec Conference paper on general approach… http://www.innovativegis.com/basis/present/GeoTec04/GIS04_Routing.htm Online book chapter on Routing and Optimal Paths… http://www.innovativegis.com/basis/MapAnalysis/http://www.innovativegis.com/basis/MapAnalysis/, Topic 19 White Paper on Delphi for GIS modeling… http://www.innovativegis.com/basis/Supplements/BM_Sep_03/T39_3_DELPHIsupplement.htm White Paper on AHP for GIS modeling… http://www.innovativegis.com/basis/Supplements/BM_Sep_03/T39_3_AHPsupplement.htm