LIVING SURVEY — measurements are reviewed continuously as new data and local evidence arrive. Seen a sign, a gate, or a better name? Submit an update no account needed · photos welcome via GitHub

Discovered lane (50.3574, -4.2782)

689.3 m · net rise 59.2 m · total ascent 68.7 m · overall 8.6% · evidence quality A (high) · Kerslake Cliff · Cornwall · share

Shape: sustained — 40% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 427 m.

Found purely from mapping and LiDAR data, and not yet matched against books, race records or lists — it may be well known to locals under a name we've never heard. It was cross-checked against the OS road network, surface models and map tags, but a discovery can still be an artifact of the terrain model or the map. Treat it as a well-evidenced hypothesis until someone has ridden it. If you know this road, tell us what you found — photographs, corrections and local knowledge all welcome; the map links below let you scout it first.

Gradient ladder what do windows mean?

Window	Maximum	Located at
2 m (diagnostic)	34%	49–51 m
3 m (diagnostic)	31%	49–52 m
5 m	29%	484–489 m
10 m	26%	479–489 m
20 m	22.1%	469–489 m
25 m	21.3%	464–489 m
50 m	18.9%	447–497 m
100 m	17.0%	457–557 m

may continue beyond end Extent detection suggests reviewing where this climb starts/ends.

Map

Check this route yourself: Google Maps route via their router · Street View at the base where coverage exists · geojson.io our exact measured line · OpenTopoMap

No aerial layer here: Britain has no open or government source of aerial photography at road scale — the pan-government APGB imagery is licensed to the public sector only, unlike the LiDAR this survey is measured from. Street View, where it exists, is the visual check.

This climb's data: OCL JSON — the full gradient ladder, quality flags and provenance in the OpenClimb Ladder format.

Access: Listed 2026-09-05 (inventory hunt wave 1): road audit — way 487211655: unnamed service way; openroads covered 77%, restricted 77%. Never silently ranked or dropped (Peter, 2026-08-27).

Measured, not vetted. This page records what the laser record shows about the road's shape — nothing more. Nobody has necessarily ridden or inspected this road for the survey, and a page here is not a recommendation and no guarantee that the road is open, surfaced, rideable or safe. Gates, private sections, missing rights of way and hazards do not show up in elevation data. Check access and conditions on the ground and make your own judgment.

Ridden it, or know better? Submit data for this climb no account needed · Share this climb

Route colour = gradient over a 25 m window: <10% 10–20% 20–25% ≥25%

Discovered lane (50.3574, -4.2782) LiDAR hillshade map with contours

Profile

The profile and gradient chart share one position — move your pointer over them and the marker follows. Colors are the gradient bands; the shaded span is the steepest 25 m. Any 25 m figure is good to about a point either way (why).

Measurement card

Elevation	Environment Agency — EA LIDAR Composite DTM 1m (2022)
Resolution / CRS	1.0 m grid, EPSG:27700; sampled every 1.0 m, bilinear interpolation
Tiles	SX3550.tif
Road centreline	OpenStreetMap (local PBF extract)
Quality status	evidence quality A; no review flags; no caveated windows
Analysis	OCL 0.1.0, analysis 0.1.0, run hunt-england-260905, calculated 2026-09-05

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:27700",
  "elevation_resolution_m": 1.0,
  "elevation_tiles": [
    "data/cache/england/bulk_dtm_1m/SX3550.tif"
  ],
  "calculated_at": "2026-09-05T01:48:11+00:00",
  "road_source": "OpenStreetMap (local PBF extract)",
  "road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
  "osm_pbf_path": "/mnt/HC_Volume_106792346/hunt-gb/regions/region-00.osm.pbf",
  "osm_snapshot": "",
  "run_id": "hunt-england-260905",
  "elevation_provider": "Environment Agency",
  "elevation_dataset": "EA LIDAR Composite DTM 1m (2022)",
  "elevation_licence": "Open Government Licence v3 \u2014 \u00a9 Environment Agency",
  "elevation_coverage_id": "13787b9a-26a4-4775-8523-806d13af58fc__Lidar_Composite_Elevation_DTM_1m",
  "elevation_tile_ids": [
    "SX3550.tif"
  ],
  "climb_origin": "discovered",
  "license": "ODbL-1.0",
  "license_url": "https://howsteep.org/licensing"
}