Lab 4 - Building Networks

For this lab, we were to complete a couple of Network Analyst tutorials in ArcGIS, and then to build a network and performing a route analysis with the intent of analyzing networks with and without certain restrictions. I completed the tutorial that walked us through the actual building of a network dataset and the tutorial showing us how to compute the best route. Next, we had to build a network dataset mainly on our own. We were provided with a file geodatabase and the input files required to create the network. Following the lab instructions, I created a network dataset in ArcCatalog, selecting No when asked if I wanted to model the traffic data. Once the network dataset was built, I added the facilities layer as Stops and used the settings in the instructions to calculate the route. It took me a little while to find the information asked for the deliverables, specifically the expression used for certain attributes, which are in the attributes tab of the network dataset itself. Then I ran the route analysis without the traffic data. I looked at the restricted turns and streets features. While inspecting the details of the restricted turns, they seem to be defined using the positions and IDs of the edges of the streets. The restrictions are also categorized by type (a classification of 7 meaning no turns are allowed). The restricted turns are also classified by the mode of transportation allowed or disallowed (some are passable by pedestrians but not by automobile, for example). The length of the restriction is also measured.
Next, I examined the Patterns and Street Patterns tables. The Patterns tables is the "Profiles" table for the network dataset. The profile describes the variation of travel speeds in 15 minute increments over a day. The Streets Patterns tables is the Streets-Profiles table. These records link edge source features with profiles in the Patterns table. By linking these tables together, I could describe the varying traffic speeds over a week. I copied the network features into a new file geodatabase, deleted the old network from the new geodatabase, and created a new network dataset, this time using the traffic data. Using the new network dataset, I created another route using the same facilities which this time includes the traffic data. The results are shown below. Without the traffic data, the route takes 97 minutes and is approximately 95,000 meters (95 km) in length. With the traffic data, the route takes 105 minutes and is approximately 100,000 meters (100 km) in length. The route could be further improved, in my opinion, if we were to add some set amount of time per stop (the default is 0 minutes).

Route Without Traffic Data

Route With Traffic Data