Lab 4 - Networks: Building Networks

In this week's lesson we revisited the topic of Network Analysis using ArcGIS's Network Analyst Extension, but this time to practice building quality and productive network datasets to maximize Solvers. So what does it take to build a good network? Many things! In our Discussion Post, I talked about two major data elements that are used as input values when creating a good network:

1. Length of a street segment: This attribute is important when building a good network because it can determine the values of other data elements. For example, knowing the length of a street segment along with the speed limit of it, we can determine the travel time on it.

2. Oneway road restrictions: This one is a big deal! At one point or another, we have all found ourselves driving in an area of town where oneways are everywhere and you might have gotten stuck in a lengthy one with no sight of a right-turn (to eventually make a U-turn) to get you back on track to your destination! Oh yea, especially when you needed to parallel park on the oneway street that also happens to be just one lane...it can get stressful, especially in a place like NYC. Because of this, in a dataset, knowing if a street segment has oneway restrictions is important to build a productive network because it can get us to our destinations in a timely and accurate fashion. It will avoid making lots of U-turns, and quite possibly save you from throwing your GPS device out the window. This piece of data is especially important for emergency situations when responders rely on speed and accuracy to arrive somewhere to save people's lives. Let's remember that emergency responders tend to drive oversized vehicles, and it would be a bad day if they are forced to make sharp turns in small streets — or worse run into incoming traffic.

For our lab assignment, we were tasked to create new network datasets from a general streets geodatabase in San Francisco, CA, while adding and removing properties in three different scenarios. Specifically, the first scenario involved using many of the default settings; in the second scenario we added Restriction Turns; and in the third scenario we added Historical Traffic Data to our network. By making these adjustments, we added functionality to out network dataset. Finally, we solved a best route problem for 19 facilities; my final scenario (as shown in the screenshot above) achieves a total time travel of 105.49 minutes.