{
 "ocl_version": "0.1.0",
 "name": "Purgatory Road",
 "slug": "purgatory-road",
 "confidence": "U",
 "reported_claims": [],
 "ladder": [
  {
   "window_m": 2.0,
   "max_gradient_pct": 53.95814226886415,
   "diagnostic": true,
   "flags": [],
   "start_distance_m": 4.0,
   "end_distance_m": 6.0,
   "start_elevation_m": 109.77047577363047,
   "end_elevation_m": 110.84963861900775,
   "min_gradient_pct": -7.319801353550304
  },
  {
   "window_m": 3.0,
   "max_gradient_pct": 52.18868463371725,
   "diagnostic": true,
   "flags": [],
   "start_distance_m": 4.0,
   "end_distance_m": 7.0,
   "start_elevation_m": 109.77047577363047,
   "end_elevation_m": 111.33613631264198,
   "min_gradient_pct": -7.294347818770082
  },
  {
   "window_m": 5.0,
   "max_gradient_pct": 51.10509163695326,
   "diagnostic": false,
   "flags": [],
   "start_distance_m": 4.0,
   "end_distance_m": 9.0,
   "start_elevation_m": 109.77047577363047,
   "end_elevation_m": 112.32573035547813,
   "min_gradient_pct": -7.246425501997464
  },
  {
   "window_m": 10.0,
   "max_gradient_pct": 50.48303081355144,
   "diagnostic": false,
   "flags": [],
   "start_distance_m": 3.0,
   "end_distance_m": 13.0,
   "start_elevation_m": 109.28661183168683,
   "end_elevation_m": 114.33491491304197,
   "min_gradient_pct": -7.080693972979475
  },
  {
   "window_m": 20.0,
   "max_gradient_pct": 33.16660314516447,
   "diagnostic": false,
   "flags": [],
   "start_distance_m": 0.0,
   "end_distance_m": 20.0,
   "start_elevation_m": 108.38059302258242,
   "end_elevation_m": 115.01391365161531,
   "min_gradient_pct": -6.952105732212885
  },
  {
   "window_m": 25.0,
   "max_gradient_pct": 26.936645762164343,
   "diagnostic": false,
   "flags": [],
   "start_distance_m": 0.0,
   "end_distance_m": 25.0,
   "start_elevation_m": 108.38059302258242,
   "end_elevation_m": 115.1147544631235,
   "min_gradient_pct": -6.924395697029922
  },
  {
   "window_m": 50.0,
   "max_gradient_pct": 14.435441606323279,
   "diagnostic": false,
   "flags": [],
   "start_distance_m": 0.0,
   "end_distance_m": 50.0,
   "start_elevation_m": 108.38059302258242,
   "end_elevation_m": 115.59831382574406,
   "min_gradient_pct": -6.859036976413449
  },
  {
   "window_m": 100.0,
   "max_gradient_pct": 9.088877813167045,
   "diagnostic": false,
   "flags": [],
   "start_distance_m": 443.0,
   "end_distance_m": 543.0,
   "start_elevation_m": 138.26165176401338,
   "end_elevation_m": 147.35052957718042,
   "min_gradient_pct": -6.3417543709537085
  }
 ],
 "shape": {
  "ascent_concentration": 0.392,
  "concentration_window_frac": 0.25,
  "longest_pitch_10pct_m": 22.0,
  "shape_class": "sustained"
 },
 "length_m": 3831.1820087671567,
 "start_elevation_m": 108.38059302258242,
 "end_elevation_m": 224.83974482939254,
 "endpoint_gain_m": 116.45915180681013,
 "overall_gradient_pct": 3.0397707950264086,
 "accumulated_ascent_m": 147.99953868895335,
 "window_maxima": {
  "max_5m": {
   "gradient_pct": 51.10509163695326,
   "start_distance_m": 4.0,
   "end_distance_m": 9.0,
   "midpoint_distance_m": 6.5,
   "start_elevation_m": 109.77047577363047,
   "end_elevation_m": 112.32573035547813,
   "start_xy": [
    276452.4246526622,
    4667445.203697421
   ],
   "end_xy": [
    276447.56714324193,
    4667446.3886937825
   ]
  },
  "max_10m": {
   "gradient_pct": 50.48303081355144,
   "start_distance_m": 3.0,
   "end_distance_m": 13.0,
   "midpoint_distance_m": 8.0,
   "start_elevation_m": 109.28661183168683,
   "end_elevation_m": 114.33491491304197,
   "start_xy": [
    276453.39873949665,
    4667444.977523065
   ],
   "end_xy": [
    276443.682424134,
    4667447.342086384
   ]
  },
  "max_20m": {
   "gradient_pct": 33.16660314516447,
   "start_distance_m": 0.0,
   "end_distance_m": 20.0,
   "midpoint_distance_m": 10.0,
   "start_elevation_m": 108.38059302258242,
   "end_elevation_m": 115.01391365161531,
   "start_xy": [
    276456.321,
    4667444.299
   ],
   "end_xy": [
    276436.89954061556,
    4667449.037793406
   ]
  },
  "max_25m": {
   "gradient_pct": 26.936645762164343,
   "start_distance_m": 0.0,
   "end_distance_m": 25.0,
   "midpoint_distance_m": 12.5,
   "start_elevation_m": 108.38059302258242,
   "end_elevation_m": 115.1147544631235,
   "start_xy": [
    276456.321,
    4667444.299
   ],
   "end_xy": [
    276432.0219526197,
    4667450.1374003105
   ]
  },
  "max_50m": {
   "gradient_pct": 14.435441606323279,
   "start_distance_m": 0.0,
   "end_distance_m": 50.0,
   "midpoint_distance_m": 25.0,
   "start_elevation_m": 108.38059302258242,
   "end_elevation_m": 115.59831382574406,
   "start_xy": [
    276456.321,
    4667444.299
   ],
   "end_xy": [
    276407.63401264045,
    4667455.63543483
   ]
  },
  "max_100m": {
   "gradient_pct": 9.088877813167045,
   "start_distance_m": 443.0,
   "end_distance_m": 543.0,
   "midpoint_distance_m": 493.0,
   "start_elevation_m": 138.26165176401338,
   "end_elevation_m": 147.35052957718042,
   "start_xy": [
    276024.23902245396,
    4667541.9210496675
   ],
   "end_xy": [
    275924.87474479305,
    4667538.745595403
   ]
  }
 },
 "window_minima": {
  "min_5m": {
   "gradient_pct": -7.246425501997464,
   "start_distance_m": 1587.0,
   "end_distance_m": 1592.0,
   "midpoint_distance_m": 1589.5,
   "start_elevation_m": 176.12999699056533,
   "end_elevation_m": 175.76767571546546,
   "start_xy": [
    275195.3321445026,
    4668125.3462405475
   ],
   "end_xy": [
    275191.029144594,
    4668127.892603338
   ]
  },
  "min_10m": {
   "gradient_pct": -7.080693972979475,
   "start_distance_m": 1584.0,
   "end_distance_m": 1594.0,
   "midpoint_distance_m": 1589.0,
   "start_elevation_m": 176.33499116650393,
   "end_elevation_m": 175.62692176920598,
   "start_xy": [
    275197.88491499505,
    4668123.77037164
   ],
   "end_xy": [
    275189.3074398841,
    4668128.910312968
   ]
  },
  "min_20m": {
   "gradient_pct": -6.952105732212885,
   "start_distance_m": 1576.0,
   "end_distance_m": 1596.0,
   "midpoint_distance_m": 1586.0,
   "start_elevation_m": 176.88416315083742,
   "end_elevation_m": 175.49374200439485,
   "start_xy": [
    275204.692302975,
    4668119.568054554
   ],
   "end_xy": [
    275187.5857351743,
    4668129.928022599
   ]
  },
  "min_25m": {
   "gradient_pct": -6.924395697029922,
   "start_distance_m": 1568.0,
   "end_distance_m": 1593.0,
   "midpoint_distance_m": 1580.5,
   "start_elevation_m": 177.42839923103668,
   "end_elevation_m": 175.6973003067792,
   "start_xy": [
    275211.49969095486,
    4668115.365737469
   ],
   "end_xy": [
    275190.168292239,
    4668128.401458153
   ]
  },
  "min_50m": {
   "gradient_pct": -6.859036976413449,
   "start_distance_m": 1546.0,
   "end_distance_m": 1596.0,
   "midpoint_distance_m": 1571.0,
   "start_elevation_m": 178.92326049260157,
   "end_elevation_m": 175.49374200439485,
   "start_xy": [
    275229.8730635761,
    4668103.268250028
   ],
   "end_xy": [
    275187.5857351743,
    4668129.928022599
   ]
  },
  "min_100m": {
   "gradient_pct": -6.3417543709537085,
   "start_distance_m": 1506.0,
   "end_distance_m": 1606.0,
   "midpoint_distance_m": 1556.0,
   "start_elevation_m": 181.26216955600717,
   "end_elevation_m": 174.92041518505346,
   "start_xy": [
    275264.8368753146,
    4668083.938573024
   ],
   "end_xy": [
    275178.97721162514,
    4668135.016570752
   ]
  }
 },
 "diagnostic_window_maxima": {
  "max_2m": {
   "gradient_pct": 53.95814226886415,
   "start_distance_m": 4.0,
   "end_distance_m": 6.0,
   "midpoint_distance_m": 5.0,
   "start_elevation_m": 109.77047577363047,
   "end_elevation_m": 110.84963861900775,
   "start_xy": [
    276452.4246526622,
    4667445.203697421
   ],
   "end_xy": [
    276450.4806825729,
    4667445.673649332
   ]
  },
  "max_3m": {
   "gradient_pct": 52.18868463371725,
   "start_distance_m": 4.0,
   "end_distance_m": 7.0,
   "midpoint_distance_m": 5.5,
   "start_elevation_m": 109.77047577363047,
   "end_elevation_m": 111.33613631264198,
   "start_xy": [
    276452.4246526622,
    4667445.203697421
   ],
   "end_xy": [
    276449.5095027959,
    4667445.911997482
   ]
  }
 },
 "diagnostic_note": "Windows <=3 m are at raster-noise scale (1-sigma raster noise alone is roughly +/-7 pp at 2 m and +/-5 pp at 3 m on a 1 m DTM). Diagnostic use only: never a headline or ranking value.",
 "quality_summary": {
  "review": [
   "max5_over_45",
   "max10_over_40"
  ],
  "extent": [
   "may_start_earlier",
   "descends_at_end"
  ],
  "suggested_summit_cut_m": 3518.0,
  "trailing_descent_m": 11.9
 },
 "provenance": {
  "analysis_version": "0.1.0",
  "sample_interval_m": 1.0,
  "interpolation": "bilinear",
  "smoothing": "none",
  "gradient_windows_m": [
   5.0,
   10.0,
   20.0,
   25.0,
   50.0,
   100.0
  ],
  "diagnostic_windows_m": [
   2.0,
   3.0
  ],
  "elevation_crs": "EPSG:26919",
  "elevation_resolution_m": 1.0,
  "elevation_tiles": [
   "data/cache/usa/ma-east/USGS_1M_19_x27y467_MA_CentralEastern_2021_B21.tif"
  ],
  "calculated_at": "2026-08-24T21:43:59+00:00",
  "road_source": "OpenStreetMap (local PBF extract)",
  "road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
  "osm_pbf_path": "data/cache/pbf/massachusetts-260822.osm.pbf",
  "osm_snapshot": "2026-08-21T20:21:11Z",
  "run_id": "redo-ma-4-260824",
  "elevation_provider": "USGS 3DEP (The National Map)",
  "elevation_licence": "Public domain \u2014 USGS 3DEP 1 m DEM, courtesy of the U.S. Geological Survey",
  "elevation_dataset": "USGS 3DEP 1 m DEM, MA_CentralEastern_2021_B21 (collected 2021)",
  "elevation_tile_ids": [
   "x27y467"
  ],
  "climb_origin": "discovered",
  "notes": "Coarse pass: max 9.1% over 200 m (Terrain 50), gain 108.3 m over 3730 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 (NE wave 1, 2026-08-25): clean-steep. Wales dials per PRODUCTION 'US ADOPTION DIALS'.",
  "canopy_check": "unavailable \u2014 no surface model (DSM or point cloud) registered for this coverage",
  "license": "ODbL-1.0",
  "license_url": "https://howsteep.org/licensing.html"
 },
 "area": {
  "place": "Sutton",
  "county": "Massachusetts"
 }
}