{
 "ocl_version": "0.1.0",
 "name": "Upper Grassy Hill Road",
 "slug": "upper-grassy-hill-road",
 "confidence": "B",
 "reported_claims": [],
 "ladder": [
  {
   "window_m": 2.0,
   "max_gradient_pct": 21.559053144417106,
   "diagnostic": true,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 157.0,
   "end_distance_m": 159.0,
   "start_elevation_m": 124.120506214054,
   "end_elevation_m": 124.55168727694235,
   "min_gradient_pct": -7.131999970908964
  },
  {
   "window_m": 3.0,
   "max_gradient_pct": 21.247542276795173,
   "diagnostic": true,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 157.0,
   "end_distance_m": 160.0,
   "start_elevation_m": 124.120506214054,
   "end_elevation_m": 124.75793248235786,
   "min_gradient_pct": -7.0316828982792385
  },
  {
   "window_m": 5.0,
   "max_gradient_pct": 20.90696137531353,
   "diagnostic": false,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 155.0,
   "end_distance_m": 160.0,
   "start_elevation_m": 123.71258441359218,
   "end_elevation_m": 124.75793248235786,
   "min_gradient_pct": -6.9272111590998975
  },
  {
   "window_m": 10.0,
   "max_gradient_pct": 20.632809048531726,
   "diagnostic": false,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 150.0,
   "end_distance_m": 160.0,
   "start_elevation_m": 122.69465157750469,
   "end_elevation_m": 124.75793248235786,
   "min_gradient_pct": -6.860550536708843
  },
  {
   "window_m": 20.0,
   "max_gradient_pct": 20.347568328209604,
   "diagnostic": false,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 143.0,
   "end_distance_m": 163.0,
   "start_elevation_m": 121.3032079473518,
   "end_elevation_m": 125.37272161299371,
   "min_gradient_pct": -6.614578873141852
  },
  {
   "window_m": 25.0,
   "max_gradient_pct": 20.178121755330835,
   "diagnostic": false,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 138.0,
   "end_distance_m": 163.0,
   "start_elevation_m": 120.328191174161,
   "end_elevation_m": 125.37272161299371,
   "min_gradient_pct": -6.43785571172225
  },
  {
   "window_m": 50.0,
   "max_gradient_pct": 19.650252946141848,
   "diagnostic": false,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 114.0,
   "end_distance_m": 164.0,
   "start_elevation_m": 115.7396954442261,
   "end_elevation_m": 125.56482191729702,
   "min_gradient_pct": -5.681784862626159
  },
  {
   "window_m": 100.0,
   "max_gradient_pct": 19.08779812012392,
   "diagnostic": false,
   "flags": [
    "canopy_or_structure"
   ],
   "start_distance_m": 72.0,
   "end_distance_m": 172.0,
   "start_elevation_m": 107.96902940550237,
   "end_elevation_m": 127.05682752562629,
   "min_gradient_pct": -4.305571331327087
  }
 ],
 "shape": {
  "ascent_concentration": 0.581,
  "concentration_window_frac": 0.25,
  "longest_pitch_10pct_m": 191.0,
  "shape_class": "stepped"
 },
 "length_m": 5469.870769701942,
 "start_elevation_m": 99.08399149827017,
 "end_elevation_m": 289.92380029690185,
 "endpoint_gain_m": 190.83980879863168,
 "overall_gradient_pct": 3.488927194691854,
 "accumulated_ascent_m": 219.49090863907858,
 "window_maxima": {
  "max_5m": {
   "gradient_pct": 20.90696137531353,
   "start_distance_m": 155.0,
   "end_distance_m": 160.0,
   "midpoint_distance_m": 157.5,
   "start_elevation_m": 123.71258441359218,
   "end_elevation_m": 124.75793248235786,
   "start_xy": [
    646382.3201766222,
    4597149.726455007
   ],
   "end_xy": [
    646378.6860918747,
    4597153.156551177
   ]
  },
  "max_10m": {
   "gradient_pct": 20.632809048531726,
   "start_distance_m": 150.0,
   "end_distance_m": 160.0,
   "midpoint_distance_m": 155.0,
   "start_elevation_m": 122.69465157750469,
   "end_elevation_m": 124.75793248235786,
   "start_xy": [
    646385.775827769,
    4597146.112803784
   ],
   "end_xy": [
    646378.6860918747,
    4597153.156551177
   ]
  },
  "max_20m": {
   "gradient_pct": 20.347568328209604,
   "start_distance_m": 143.0,
   "end_distance_m": 163.0,
   "midpoint_distance_m": 153.0,
   "start_elevation_m": 121.3032079473518,
   "end_elevation_m": 125.37272161299371,
   "start_xy": [
    646390.2301130289,
    4597140.725331609
   ],
   "end_xy": [
    646376.4601116554,
    4597155.167772712
   ]
  },
  "max_25m": {
   "gradient_pct": 20.178121755330835,
   "start_distance_m": 138.0,
   "end_distance_m": 163.0,
   "midpoint_distance_m": 150.5,
   "start_elevation_m": 120.328191174161,
   "end_elevation_m": 125.37272161299371,
   "start_xy": [
    646392.8655894072,
    4597136.485915025
   ],
   "end_xy": [
    646376.4601116554,
    4597155.167772712
   ]
  },
  "max_50m": {
   "gradient_pct": 19.650252946141848,
   "start_distance_m": 114.0,
   "end_distance_m": 164.0,
   "midpoint_distance_m": 139.0,
   "start_elevation_m": 115.7396954442261,
   "end_elevation_m": 125.56482191729702,
   "start_xy": [
    646400.4131977701,
    4597114.012910965
   ],
   "end_xy": [
    646375.718118249,
    4597155.83817989
   ]
  },
  "max_100m": {
   "gradient_pct": 19.08779812012392,
   "start_distance_m": 72.0,
   "end_distance_m": 172.0,
   "midpoint_distance_m": 122.0,
   "start_elevation_m": 107.96902940550237,
   "end_elevation_m": 127.05682752562629,
   "start_xy": [
    646385.7034095619,
    4597075.337364098
   ],
   "end_xy": [
    646369.7821709974,
    4597161.201437317
   ]
  }
 },
 "window_minima": {
  "min_5m": {
   "gradient_pct": -6.9272111590998975,
   "start_distance_m": 4408.0,
   "end_distance_m": 4413.0,
   "midpoint_distance_m": 4410.5,
   "start_elevation_m": 282.2114856121535,
   "end_elevation_m": 281.86512505419853,
   "start_xy": [
    645407.53996093,
    4601121.100041455
   ],
   "end_xy": [
    645410.3170468978,
    4601125.248865231
   ]
  },
  "min_10m": {
   "gradient_pct": -6.860550536708843,
   "start_distance_m": 4408.0,
   "end_distance_m": 4418.0,
   "midpoint_distance_m": 4413.0,
   "start_elevation_m": 282.2114856121535,
   "end_elevation_m": 281.52543055848264,
   "start_xy": [
    645407.53996093,
    4601121.100041455
   ],
   "end_xy": [
    645412.4159793064,
    4601129.737717699
   ]
  },
  "min_20m": {
   "gradient_pct": -6.614578873141852,
   "start_distance_m": 4400.0,
   "end_distance_m": 4420.0,
   "midpoint_distance_m": 4410.0,
   "start_elevation_m": 282.7239808509608,
   "end_elevation_m": 281.40106507633243,
   "start_xy": [
    645402.2997729102,
    4601115.055173424
   ],
   "end_xy": [
    645412.8970502925,
    4601131.672182305
   ]
  },
  "min_25m": {
   "gradient_pct": -6.43785571172225,
   "start_distance_m": 4396.0,
   "end_distance_m": 4421.0,
   "midpoint_distance_m": 4408.5,
   "start_elevation_m": 282.9507423293808,
   "end_elevation_m": 281.3412784014502,
   "start_xy": [
    645399.3950563637,
    4601112.315466409
   ],
   "end_xy": [
    645413.0184542688,
    4601132.664785486
   ]
  },
  "min_50m": {
   "gradient_pct": -5.681784862626159,
   "start_distance_m": 4247.0,
   "end_distance_m": 4297.0,
   "midpoint_distance_m": 4272.0,
   "start_elevation_m": 288.7643730596445,
   "end_elevation_m": 285.92348062833145,
   "start_xy": [
    645283.9128759468,
    4601018.262840881
   ],
   "end_xy": [
    645322.3315766592,
    4601050.193958511
   ]
  },
  "min_100m": {
   "gradient_pct": -4.305571331327087,
   "start_distance_m": 4216.0,
   "end_distance_m": 4316.0,
   "midpoint_distance_m": 4266.0,
   "start_elevation_m": 289.65502275251833,
   "end_elevation_m": 285.34945142119125,
   "start_xy": [
    645272.1284308566,
    4600990.548660325
   ],
   "end_xy": [
    645337.2134491726,
    4601062.0062347725
   ]
  }
 },
 "diagnostic_window_maxima": {
  "max_2m": {
   "gradient_pct": 21.559053144417106,
   "start_distance_m": 157.0,
   "end_distance_m": 159.0,
   "midpoint_distance_m": 158.0,
   "start_elevation_m": 124.120506214054,
   "end_elevation_m": 124.55168727694235,
   "start_xy": [
    646380.912072094,
    4597151.145329642
   ],
   "end_xy": [
    646379.4280852812,
    4597152.486143999
   ]
  },
  "max_3m": {
   "gradient_pct": 21.247542276795173,
   "start_distance_m": 157.0,
   "end_distance_m": 160.0,
   "midpoint_distance_m": 158.5,
   "start_elevation_m": 124.120506214054,
   "end_elevation_m": 124.75793248235786,
   "start_xy": [
    646380.912072094,
    4597151.145329642
   ],
   "end_xy": [
    646378.6860918747,
    4597153.156551177
   ]
  }
 },
 "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": {
  "overhead_obstruction": {
   "obstruction_threshold_m": 2.0,
   "obstructed_fraction": 0.285,
   "obstruction_max_height_m": 28.84,
   "flagged_windows_m": [
    2,
    3,
    5,
    10,
    20,
    25,
    50,
    100
   ]
  },
  "review": [],
  "extent": [
   "may_start_earlier"
  ]
 },
 "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:26918",
  "elevation_resolution_m": 1.0,
  "elevation_tiles": [
   "data/cache/usa/ct/USGS_1M_18_x64y460_CT_Statewide_C16.tif",
   "data/cache/usa/ct/USGS_1M_18_x64y461_CT_Statewide_C16.tif"
  ],
  "calculated_at": "2026-09-04T19:12:35+00:00",
  "road_source": "OpenStreetMap (local PBF extract)",
  "road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
  "osm_pbf_path": "data/cache/pbf/connecticut-2026-08-23.osm.pbf",
  "osm_snapshot": "2026-08-22T20:21:28Z",
  "run_id": "us-hs-bench-260904",
  "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, CT_Statewide_C16 (collected 2016)",
  "elevation_tile_ids": [
   "x64y460",
   "x64y461"
  ],
  "climb_origin": "discovered",
  "canopy_source": {
   "kind": "ept_corridor_max_return",
   "ept_source": "https://usgs-lidar-public.s3-us-west-2.amazonaws.com/CT_Statewide_B3_2016",
   "ept_crs": "EPSG:3857",
   "station_coverage": 1.0,
   "cell_ground_m": 1.0,
   "nodes_failed": 0
  },
  "license": "ODbL-1.0",
  "license_url": "https://howsteep.org/licensing.html"
 },
 "area": {
  "place": "Southbury",
  "county": "Connecticut"
 }
}