1. Copyright © 2006 by Maribeth H. Price 14-1 Chapter 14 Analyzing Networks

2. Copyright © 2006 by Maribeth H. Price 14-2 Outline Learning the function and terminology of simple networks Understanding different types of networks Performing tracing analysis on networks Understanding how networks are constructed

3. Copyright © 2006 by Maribeth H. Price 14-3 Geometric networks Built inside a feature dataset May have many participating feature classes Requires ArcEditor or ArcInfo to build

4. Copyright © 2006 by Maribeth H. Price 14-4 Network components Composed of edges and junctions edges junctions

5. Copyright © 2006 by Maribeth H. Price 14-5 Network structure Geometric network is composed of feature classes Logical network consists of tables describing network relationships

6. Copyright © 2006 by Maribeth H. Price 14-6 Types of networks Transportation Networks Material moves as it wills Utility Networks Material flow dictated by network geometry and sources/sinks

7. Copyright © 2006 by Maribeth H. Price 14-7 Network problems Transportation –What is the best path to travel to sixteen delivery locations? –What is the likely service area of a fire station based on travel time? –What is the shortest path from point A to point B? –What is the shortest path which avoids narrow streets? Utility networks –If a valve fails, which customers will be affected? –If I have to close this pipe for repairs, can I reroute water through another path to minimize service disruption? –How will contamination at one location propagate through the network? –Which sewer lines serve only residential customers?

8. Copyright © 2006 by Maribeth H. Price 14-8 Network tracing Tracing solvers used to find solutions to network problems

9. Copyright © 2006 by Maribeth H. Price 14-9 Flags and barriers Flags indicate points of interest (start, end, stops) Barriers stop flow through a feature Types should match when solving a problem Junction flag Junction barrier Edge barrier Edge flag

10. Copyright © 2006 by Maribeth H. Price 14-10 Network Utility Analyst toolbar Establish flowSolve

11. Copyright © 2006 by Maribeth H. Price 14-11 Finding paths Place flags and barriers Solve Path with fewest edgesPath with construction Default cost is number of edges traversed

12. Copyright © 2006 by Maribeth H. Price 14-12 Finding shortest paths Use weights to override default cost Find shortest path with distance weight Shortest path with three stops Visited in order that flags are placed

13. Copyright © 2006 by Maribeth H. Price 14-13 Setting weights Analysis options Set for junctions or edges Edge weights have direction Usually need both directions Possible weights: Distance, travel time, wait at stop lights, voltage or pressure drops, etc.

14. Copyright © 2006 by Maribeth H. Price 14-14 Viewing flow directions Flow must be established for utility networks Flow direction symbols can be viewed and changed Set view scale to hide arrows at smaller scales

15. Copyright © 2006 by Maribeth H. Price 14-15 Finding connected Find features connected to or disconnected from the flagged feature Water lines supplied by an intake gallery

16. Copyright © 2006 by Maribeth H. Price 14-16 Finding loops Used to find places with indeterminate flow Primarily used for utility networks Flag Flow Loop

17. Copyright © 2006 by Maribeth H. Price 14-17 Directional tracing Find Upstream –Trace the flow from a feature to its source Trace Downstream –Find the area disrupted by a line break

18. Copyright © 2006 by Maribeth H. Price 14-18 Tracing with accumulation Uses default cost (edges) or set weights Returns total cost associated with found trace

19. Copyright © 2006 by Maribeth H. Price 14-19 Find Common Ancestors Finds common source for a set of flags Use to locate possible line break from a set of service calls Probable break

20. Copyright © 2006 by Maribeth H. Price 14-20 Advanced analysis Avoid certain features when tracing Trace only on unselected features to avoid certain streets

21. Copyright © 2006 by Maribeth H. Price 14-21 Advanced analysis Return selection Use statistics to find length of connected water lines

22. Copyright © 2006 by Maribeth H. Price 14-22 Network analysis options Tracing on selected or unselected features Inclusion of features with indeterminate flow Flag/barrier snapping General options

23. Copyright © 2006 by Maribeth H. Price 14-23 Results options Return result as drawing or as a selection All features or those stopping trace Return edges, junctions or both

24. Copyright © 2006 by Maribeth H. Price 14-24 Weight filters Use to exclude certain weights from analysis –Screen out short stop sign waits from longer traffice light waits

25. Copyright © 2006 by Maribeth H. Price 14-25 Building networks 1231 Simple edges— Edges may have junctions only on their endpoints Complex edges— Edges may have junctions between their endpoints Useful for query and management, such as a water main with many laterals

26. Copyright © 2006 by Maribeth H. Price 14-26 How to build a network Ensure network features are topologically valid and inside a feature dataset Create new network for the feature dataset –Specify network layer –Simple or complex edges –Assign weights Requires an ArcEditor or ArcInfo license. To build a road network using your textbook data, see “Building a simple network” in the Skills Reference section.

27. Copyright © 2006 by Maribeth H. Price 14-27 Tools for managing networks Domains and subtypes –Used to establish network attribute codes Pipes can only be 3-in, 6-in, or 12-in Default sizes and flow rates for different types Connectivity rules –Define which features can connect to each other and how T-valve must connect to three pipes 6-in line must connect to 3-in line through a coupler