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   ],
   "width_at_max25_m": 2.5,
   "window_stations": 7,
   "single_track": false,
   "single_track_rule": "PROVISIONAL (2026-09-15): width_p10_m <= 3.0 m with bounded_share >= 0.6; recorded, not a rule",
   "status": "ok",
   "source": "dtm",
   "station_m": 25.0,
   "window_station_m": 5.0,
   "halfwidth_m": 6.0,
   "step_m": 0.25,
   "level_tol_m": 0.12,
   "break_min_m": 0.3,
   "stations_failed": 0,
   "hedge_to_hedge": {
    "stations": 118,
    "stations_resolved": 118,
    "width_median_m": 3.0,
    "width_p10_m": 1.0,
    "width_min_m": 0.5,
    "width_max_m": 11.25,
    "bounded_share": 0.873,
    "unbounded_share": 0.127,
    "confidence_median": 1.0,
    "width_median_bounded_m": 3.0,
    "window_m": [
     1741.0,
     1766.0
    ],
    "width_at_max25_m": 2.75,
    "window_stations": 7,
    "status": "ok",
    "source": "dsm",
    "station_m": 25.0,
    "window_station_m": 5.0,
    "halfwidth_m": 6.0,
    "step_m": 0.25,
    "level_tol_m": 0.5,
    "break_min_m": 0.3,
    "stations_failed": 0
   }
  },
  "unmapped_bridge_span": {
   "start_m": 1393.0,
   "end_m": 1561.0,
   "span_m": 168.0,
   "floor_at_m": 1450.0,
   "depth_m": 9.9,
   "drop_m": 5.9,
   "surface": "raw",
   "window_start_m": 1741.0,
   "window_end_m": 1766.0,
   "gap_m": 180.0,
   "unstable": false,
   "perturbation_hits": 3,
   "note": "The ground falls 6 m below the road between 1393 m and 1561 m \u2014 10 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 1741 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": 17.09,
   "max25_pct": 16.47
  },
  "license": "ODbL-1.0",
  "license_url": "https://howsteep.org/licensing"
 },
 "area": {
  "place": "Cae'r-bryn",
  "county": "Sir Gaerfyrddin - Carmarthenshire"
 }
}