GIS5935 M1.3: Assessment

 

    In this lab, we conducted a spatial comparison of road network completeness between the TIGER_Roads and Street_Centerlines shapefiles within Jackson County. The first step involved calculating the total length of each network after projecting and converting the measurements from feet to kilometers. TIGER_Roads had a summed length of 1138.3 km, while Street_Centerlines totaled 1087.0 km, indicating that TIGER appeared more complete in terms of overall coverage.

    To assess completeness at a finer scale, I used a grid-based approach. I clipped both road datasets using the pairwise clip tool so that only segments falling within the grid polygons remained. This preserved the original attributes and allowed me to summarize road lengths within each grid cell using the GRIDCODE field. The result was two tables showing total road length per grid square for each dataset.

    For the third deliverable, I compared the summed lengths per grid cell to determine which dataset was more complete in each location. Street_Centerlines was more complete in 232 of the 296 grid squares, while TIGER_Roads was more complete in 64. This comparison was refined further for the map in deliverable 4, which categorized the grid squares based on percent difference. The final count showed 225 squares favoring Street_Centerlines, 55 favoring TIGER_Roads, and 16 with negligible differences.

    The map titled “Spatial Assessment of TIGER vs. Street Centerline Coverage” visualizes these differences using a choropleth of the grid polygons. A diverging color scheme was applied, with red representing TIGER-dominant areas, blue for Street_Centerlines dominance, and white for near-equal coverage. This visual summary shows the spatial distribution of completeness and supports a conclusion that Street_Centerlines offers more detailed coverage across most of the study area.