GIS 5935 - Lab 4 - Building Networks

The first part of this week's assignment was to run through some ArcGIS Network Analyst tutorial exercises.  In the second part of the lab we practiced building network datasets.  Using a provided Streets feature class we created a new network dataset.  The first network dataset modeled turns but did not have restricted turns and did not model traffic or driving directions.  The network was then built and added to an ArcMap data frame.  Using the Network Analyst toolbar we started a new Route Analysis.  Stops along the route were created by uploading a provided Facilities point layer.  The route was solved and produced a path that took 105.49 total minutes to travel and was 10.06 kilometers in length.

Next we returned to the Properties window of the new network dataset and under the Turns tab added RestrictedTurns.   RestrictedTurns was a provided feature class that specified conditions for when turns were and were not allowed.  This feature class also specified whether the restriction applied to  specific transportation modes; such as cars, trucks, pedestrians, etc.  The network dataset had to be rebuilt after RestrictedTurns was added.  The route analysis was rerun.  Despite adding RestrictedTurns the modeled route was unaffected by the turn restrictions and resulted in the same travel time and path length as the first route analysis.

For our final analysis we had to start over and use a copy of the supplied geodatabase and create a brand new network dataset.   This time we used the same settings as the previous network setup but we chose to model traffic using two provided profile tables, Patterns and Streets_Patterns.  These tables linked street segment features with traffic speed profiles for each day of the week.  The new network dataset was added to a data frame and another route analysis was performed using the same Facilities points as stops along the route.  Even with historical traffic data added to the network dataset there was no change in the results of the route analysis.   The total travel time and path length remained the same 105.49 minutes and 10.06 km.

I have a new appreciation for the level of detail that is needed in a Streets layer to create a more accurate network dataset.  The Network Analyst can provide a user with many options in analyzing potential routes and their associated costs.