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  "road_source": "OpenStreetMap (local PBF extract)",
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  "osm_snapshot": "2026-08-12T20:21:46Z",
  "elevation_provider": "Environment Agency",
  "elevation_dataset": "EA LIDAR Composite DTM 1m (2022)",
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  "notes": "Coarse pass: max 17.6% over 200 m (Terrain 50), gain 137.1 m over 1517 m way. EXTENDED by graph walk: +1 segment(s) at base, +0 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (England launch slice 2026-08-16): clean-steep."
 },
 "area": {
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  "county": "Somerset"
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}