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   "window_start_m": 252.0,
   "window_end_m": 277.0,
   "gap_m": 0.0,
   "unstable": false,
   "perturbation_hits": 3,
   "note": "The ground falls 12 m below the road between 85 m and 257 m \u2014 16 m below the straight line joining the profile either side of it \u2014 and climbs back to that line, with the steepest 25 m at 252 m. That is a ravine under a deck OSM does not tag as a bridge, so no mask fired. Re-measure with mask_ranges_m over the span before this maximum stands (unmapped-bridge-span, Peter 2026-09-20)."
  },
  "remeasured": {
   "on": "2026-09-21",
   "why": "corpus re-measure 2026-09-21: a mask that exists today reaching a page published before it did; fallers only (Peter: fold the fallers)",
   "published_max25_pct": 23.07,
   "max25_pct": 19.36
  },
  "license": "ODbL-1.0",
  "license_url": "https://howsteep.org/licensing"
 },
 "area": {
  "place": "St Mellion",
  "county": "Cornwall"
 },
 "review_flags": [
  {
   "kind": "possible-bridge-or-hollow",
   "span_m": [
    85.0,
    258.0
   ],
   "status": "pending-human-review",
   "noted": "2026-09-21",
   "figure_adjusted": false
  }
 ]
}