Module 4- Special Topics in GIS -Network Building

Routes with no restrictions (left) and accounting for traffic (right)

This week's lab was super-challenging.  The Network Analyst software of ArcMap is quite sophisticated, and so it's sometimes hard to understand how it works and get the results you're looking for.

In our case, we made a route to go among 19 stops, with no restricted turns.  A new network dataset is created within a geodatabase, and feature dataset, with street, traffic and restricted turn feature classes associated with it.  The traffic data is based on historical traffic patterns, which are actually models of how traffic ebbs and flows at different speeds over the course of a day, on different days of the week.  Rather than attaching all the traffic data to the specific streets, each street is referred to the particular pattern that is best suited to it.  A general traffic situation can be created for the streets, but live traffic data can also be accessed and applied to the streets on a minute-by-minute basis.

As can be seen from the two figures above, the route will change depending on whether or not we have no restrictions in the form of restricted turns or traffic.  The route at left is with no restrictions, and the route on the right takes into account traffic patterns.  By changing the path in a couple of places, indicated by the arrows, the travel time can be optimized.  Total time went from 105 minutes in the non-restricted turn case, to 107 minutes once traffic effects were added and the route was adjusted by the Network Analyst.