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osmWorkflow/.trellis/tasks/08-13-native-road-compiler/research/two-area-comparison.md

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Two-Area Native Road Comparison

Runs

2026-08-14:

npm run road:compile -- --config config/areas/nantaizi-lake-innovation-valley.json
npm run build:area -- --config config/areas/hanyang-block.json --stages intermediates
npm run road:compile -- --config config/areas/hanyang-block.json

comparison.json is a coverage and diagnostic record. Feature counts are not a geometry-quality score: osm2streets and the native compiler segment roads at different levels.

Area Directional roads Native surfaces Native junctions Movements Internal ends Manual candidates osm2streets road surfaces
nantaizi-lake-innovation-valley 34 19 6 46 4 2 50
hanyang-block 475 352 20 369 161 83 1826

Observed Failure Modes

The hanyang osm2streets/QGIS run completed, but its log reported repeated:

  • roads trimmed into oblivion;
  • degenerate intersections that could not be collapsed because layers, names, highway types, or lane specifications differ;
  • intersection polygon requests with no roads.

The native compiler did not hide the related uncertainty. It reported 161 internal road ends. Eighty-three have one or more nearby, direction-compatible candidate departures within 35 metres; these remain suggestions for explicit review rather than automatic topology edits. The initial five one-way junctions that lacked connector curves now publish road-surface envelopes based on their semantic movements. Across hanyang, 369 movements are identified: 243 require a connector curve, while 126 are continuous at their OSM node and intentionally have no separate geometry.

Resulting Priorities

  1. Keep manual candidate suggestions and semantic overrides as the correction path for near-miss topology. Do not bulk-connect candidates.
  2. Expand ordinary junction support from 3/4 physical approaches only after identifying a repeated unsupported topology; one-way movements that are continuous at a node are already supported without fake connector geometry.
  3. Add an inspectable movement artifact so turn geometry is not the only representation of a road-to-road movement.
  4. Use a visual review of a few explicit hanyang diagnostics before changing connection-distance or road-class rules.