For this week's module, we learned how to determine the quality of road networks by employing methodology similar to a study conducted by Haklay (2010). The completeness of two road networks, Street Centerlines and TIGER, were determined by measuring the total lengths of road in Jackson County, Oregon. We were provided a polygon grid of the county. By using the summarize within tool, I was able to calculate the total kilometers of road for each road network shapefile in each grid.The Tiger shapefile contains 11382.7 Km of road segments and
the Street Centerlines shapefile contains 10873.3 Km of road segments. The
Tiger road network is the most complete.
I also created a join for the two road shapefiles by joining the Gridcode fields. I did a quality check and selected by attribute for each
length field to see if any Grids had a value of zero and discovered two. I
changed the field value to Null. I added a field and calculated the field with
the statement:
!Grid_SummarizeWithin_Street.SUM_Length_KILOMETERS!>!Grid_SummarizeWithin_Tiger.SUM_Length_KILOMETERS!
This returned a value of 1 if it was true and a value of 0
if it was false. The value of 1 indicated the Street Centerline was more
complete and the value of 0 indicated the Tiger network was more complete. The Street Centerline network was more complete than the
Tiger network in 134 out of 297 grids. The Tiger network was more complete than
the Street Centerline in 162 out of 297 grids. . One of the grids did not contain any road segments and one
only contained 5 km of TIGER road so both were excluded from the map.
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