Lab 2: Network Analyst
Introduction:
This lab teaches you how to use the Network Analyst toolbar to create networks and calculate routes, service areas, and optimal locations.
Where can I find the lab instructions?
Same as Lab 1, you will use the web-based help from ESRI's online ArcGIS Resource Center (http://resources.arcgis.com/content/web-based-help). For this lab, you need to read ArcGIS 10 Desktop Help on the Network Analyst extension. Click on the ESRI web-based help link above, click on ArcGIS Desktop Help (or the plus sign) to expand its contents and click on the ArcGIS 10 Desktop Help hyperlink to go to the main page of ArcGIS 10 Help Library (or click here to go directly to the page). Use the Table of Contents on the left pane to find the assigned lab readings.
Instructions:
The documents related to Network Analyst are in the Professional Library, under the Extensions container. Open the Network Analyst online help page. Read the first 6 topics, which include "What is Network Analyst?", "A quick tour of Network Analyst", "Essential Network Analyst vocabulary", "Licensing and the Network Analyst extension", " Configuring the Network Analyst environment", and "Network Analyst tutorial exercises." The last topic will direct you to the tutorial that will be used for this lab. You can also find the tutorial page from under the "Guide books" container. Follow the tutorial instructions for exercises 1 - 5 and 9 (skip 6, 7, and 8), and answer the following questions as you go along. If you prefer, a pdf copy of the instructions, called "network-analyst-tutorial.pdf", can be found on the I: drive under Students\Data\GIS\ArcTutor\10\ArcGIS_10_Tutorial_PDFs\extensions. Please do NOT print the pdf!
The tutorial data can be found on the I: drive under Students\Data\GIS\ArcTutor\10. Copy the whole Network Analyst folder to your own drive and use this as your workspace for this lab. The tutorial indicates not to save any map at the end of an exercise. You may wish to save your maps to preserve work you've done. However, if you wish to repeat an exercise, be sure to get a fresh copy of the maps off the I: drive.
Network Analyst Questions
Ex. 1 Creating a Network Dataset
1. What is the difference between a geodatabase network and a shapefile network?
2. When would you use elevation settings in a network?
3. Why would you use historical traffic data?
4. What are cost attributes? Give an example.
Ex. 2 Creating a multimodal network dataset
5. Why would you use a multimodal network? Give an example of when this would be useful.
6. How do connectivity groups work? Include how edges and junctions work in connectivity groups.
7. What does a cost value of -1 mean?
Ex. 3 Routing
8. What is the total time and distance of your route without barriers? With barriers?
9. Make a map of your route with barriers.
Ex. 3B Getting to the Tower!
Load Exercise05.mxd from the tutorial. Remove the stores and warehouses layers from the table of contents. You will use this map again later in exercise 5 so go to File > Save As and save it as "Exercise03_B". This will preserve the Exercise05 map for later.
= Add a new route from the Network Analysis toolbar.
= Add the Eiffel Tower to Stops
= Right-click on Stops and select Find Address.
= Change the locator to 9.3.1 World Places (ArcGIS Online).
= Type in "Eiffel Tower" next to Single Line Input and click Find.
= Click on the entry in the bottom window for the Eiffel Tower to select it.
= Right-click and select "Add as Network Analysis Object". You will see a new entry under stops at the location of the Eiffel Tower. Close the Find Address window.
= Use the Create Network Location tool to add another stop on the other side of town from the Eiffel Tower.
= Click Network Layer Properties button and under the Analysis Settings tab set impedance to Pedestrian Time and uncheck Oneway since pedestrians can walk in either direction. Click OK.
= Click the Solve button. Open the direction window. Make a map of your route and include the total time and distance using a textbox.
= Add another stop in a different part of town to your map using the Create Network Location tool.
= Change the order of stops by dragging them in the table of contents so the Eiffel Tower is the last stop.
= Open Network Layer Properties > Analysis settings and set impedance to Drive Time and check Oneway since drivers must obey one-way streets. Also check Reorder Stops to Find Optimal Route and leave Preserve First and Last Stop checked. Change U-Turns at Junctions to Not Allowed. Click OK.
= Click the Solve button. Open the direction window. Make a map of your route and include the total time and distance using a textbox.
Ex. 4 Closest Facility
Use the Magnifier Window and Select/Move Network Location tool to move the incident to a different point on the map. Solve for the new location (change the Default Cutoff value if needed to get at least one facility). Make a map of the result and include the total time and distance from the facilities to the incident on the map using a text box.
Ex. 5 Service Area
10. Before relocating the least accessible warehouse, how many stores are not served by the warehouses?
11. After relocation warehouse 2, how many stores do warehouses 3 and 5 serve individually and how much time does it take to get from the warehouse to each store?
Make a map of the new service areas Polygons sublayer and the OD Cost Matrix Lines sublayer on top of the Paris basemap. Include the stores and warehouses point layers.
Ex. 9 Location-Allocation
12. What is the difference between the "Demand to Facility" and the "Facility to Demand" options under the Analysis settings in the Analysis Layer Properties? Give an example of when you would use each.
13. There are many problem types to solve under advanced settings for location-allocation. In your own words, explain the maximize attendance problem and why this is appropriate to use for this exercise. Explain how another problem type would work for locating a retail store.
14. What is a huff model and what assumption does it make?
15. Change the target market share % to 100%. What happens? How much market share do you achieve and how many facilities does it take? Why did you not get 100%?