Lab 2: Determining Quality of Road Networks

This week's lab involved assessing the accuracy of road networks using a standardized protocol established by the National Standard for Spatial Data Accuracy (NSSDA). We compared the accuracy of two different data sets that represented Albuquerque, NM area.  The first was a local data set from the city of Albuquerque, the second was a national data set from StreetMaps USA (distributed by ESRI).  The process involved extracting intersections from both data sets and then digitizing the "true" location of the intersection using aerial imagery.  The distribution of intersections was quasi-random fairly thorough throughout the study area (see image at right of selected intersections).  It was expect, based on quick initial assessment, that the city data was more accurate than the national data set.  Our results showed this to be true:

Digitized features of the road network database from the city of Albuquerque tested 13.09 feet horizontal accuracy at the 95% confidence level using NSSDA testing procedures.

Digitized features of the road network database from StreetMaps USA tested 688.94 feet horizontal accuracy at the 95% confidence level using NSSDA testing procedures.