Part III. Creating a Network Data Set

  1. Open ArcCatalog and locate our geodatabase.
  2. Right click on our geodatabase and click “New” then “Feature Data Set”
  3. We will add a new feature dataset to called “ca_transportation”
  4. Right click on the “ca_transportation” feature class and select “Import Feature Class”
  5. Fill out the dialogue box as follows:
    • For Input features, select the shapefile we have been working on: “ca_roads”
    • For Output Location, select the feature class “ca_transportation”
    • For Output Feature Class put “ca_roads_1”
  6. Click “OK” to import the Feature Class into the “ca_transportation” layer.
  7. Right click on “ca_transportation” and go to “Add New Network Dataset”
  8. Proceed through the New Network Dataset Wizard:
    1. Give it a name
    2. Choose ca_roads_1 as the feature class participating in the network dataset.
    3. Choose to model turns in the network.
    4. Choose “None” for elevation modeling.
    5. Add an attribute for the network dataset called “Minutes”
    6. Make sure the units are minutes in the dialogue box.
    7. In evaluators, make sure the that “Type” is Field and that the Value is “Time_Minutes”
    8. Duplicate the “Minutes” field
    9. Change the value from “Time_Minutes” to “Time_Minutes_LA”; this will be used to model traffic in LA.
    10. Rename “Minutes_2” to “Minutes_LA”
  9. Title the network dataset as “ca_transportation_ND”
  10. Choose “yes” to build the Network Dataset.

Take a break while the Network Data Set builds

Part IV. Network Analysis

  1. Close ArcCatalog and re-open ArcMap
  2. Add the following layers into your map:
    • ca_cities
    • ca_counties
    • Go into the “ca_transportation feature class” and add:
      • “ca_transportation_ND”
        • Do not add all features that participate in the network database as we don’t really need them.
  3. Go to “Customize” and then “Extensions”.
  4. Make sure the Network Analyst Extension has a check mark next to it, indicating that it is on.
  5. Right click anywhere near the toolbar and click on “Network Analyst” to turn on the Network Analyst Toolbar.
  6. Click the Network Analysis Window Icon:
  7. Our task will be to calculate an Origin-Destination Cost Matrix from the most populous city in California to the next 10 populous cities.
  8. Click “New OD Cost Matrix”
  9. New layers should propagate in both the Network Analysis window and the Table of Contents for the project.
  10. Open the attribute table for ca_cities and order by population_2007.
  11. Select the highest value, which happens to be Los Angeles.
  12. With the city highlighted, we will right click on “Origin” and click “Load”
  13. Return to the table and choose the next 10 cities:
  14. Right click on Destinations:
  15. Load the data in.
  16. Close the attribute table.
  17. Go back to the Network Analyst toolbar and click on “Solve”
  18. The Origin-Destinations will be calculated.
  19. Right click on “Lines” and open the attribute table for the to see to OD-Matrix.
  20. Export as a csv file to save it out of ArcMap.
  21. To simulate Los Angeles traffic, we will use the Minutes_LA field.
  22. First, let’s copy the OD Matrix we just made, by clicking on the Layer in table of contents and clicking “Copy”
  23. Right click on the “Layer Properties” and choose “Paste Layer”
  24. You should rename the layer to “OD Matrix LA”
  25. Now on the Network Analyst window click on “OD Matrix Properties”
  26. Switch to the “Analysis Settings” window
  27. Choose Minutes_LA
  28. Choose to solve the analysis again.
  29. Open the attribute table for the lines.
  30. Compare the two OD-Matrices.

Pop quiz: Travel to which cities have been negatively impacted by Los Angeles traffic?