| name | ground-truth-diff |
| description | Diff OSM geometry and attributes against TIGER/Line 2024 to identify import drift, new roads, and name-field artifacts in MetroNow zones. |
| when_to_use | User mentions TIGER 2024, geometry drift, name artifacts, new roads, comparing OSM to Census data, or Mac Donald / O Toole style name errors |
| allowed-tools | Read Grep Glob Bash(python *) Bash(curl *) |
| argument-hint | [zone] |
| arguments | ["zone"] |
Ground-Truth Diff Against TIGER 2024
Compare OSM against TIGER/Line 2024 for zone: $zone
TIGER/Line 2024 source
- File:
tl_2024_39061_roads.zip (Hamilton County, FIPS 39061)
- Download: Census Bureau TIGER/Line Shapefiles (released September 26, 2024)
- Data currency: Through May 2024
- 2025 vintage adds augmented fullname fields and address ranges
What the diff reveals
Geometry drift
Ways that were imported in 2007 from TIGER 2005 but have since been updated in the Census Bureau's data. Differences indicate either:
- OSM was corrected (good — confirms human review happened)
- OSM was NOT corrected and the road has actually moved/changed (cleanup candidate)
New roads
Roads in TIGER 2024 that have no OSM equivalent — genuinely new construction since 2005. Particularly relevant for the MetroNow zones where suburban development is active.
Name-field artifacts (RESEARCH-FINDINGS Section 2 Item 3)
The 2007 import introduced systematic name errors:
- USPS abbreviation spacing: "Mac Donald St" → should be "MacDonald Street"
- Stripped apostrophes: "O Toole Avenue" → should be "O'Toole Avenue"
- Stripped diacritics: "Canada Road" for "Cañada Road" (the
ñ was lost in the 2007 import)
- ALL CAPS remnants: Some ways still have uppercase names from TIGER
TIGER 2024 has corrected many of these. Diffing reveals which OSM ways still carry the 2005-era name.
Highway classification drift
The original import mapped CFCC A4x → highway=residential by default. TIGER 2024 uses updated MAF/TIGER Feature Class Codes (MTFCC) that better distinguish:
- S1400: Secondary road →
highway=tertiary or unclassified
- S1740: Private road →
highway=service + access=private
- S1200: Secondary road (named) →
highway=secondary
Cross-referencing TIGER 2024 MTFCC against OSM highway=* reveals misclassifications.
Diff workflow
- Download
tl_2024_39061_roads.zip from Census Bureau
- Extract and load into a spatial format (GeoJSON, PostGIS, or Shapefile)
- Clip to zone bbox from
src/osm/zones/__init__.py (the ZONES dict)
- For each TIGER 2024 road segment:
- Find matching OSM way(s) by proximity + name similarity
- Compare: geometry (Hausdorff distance), name, MTFCC vs highway tag
- Flag mismatches as correction candidates
- Output: CSV of candidates with OSM way ID, TIGER LINEARID, and specific mismatches
