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Discovered lane (52.3814, -3.7004)

4041.0 m · net rise 243.7 m · total ascent 250.2 m · overall 6.0% · evidence quality A (high) · Cwm Brithgwm · Powys · share

Shape: stepped — 45% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 274 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?

≈ appears only on the 2–3 m diagnostic rows here, which does not lower the evidence quality: those windows are never headline values or ranking keys, so the letter reflects the standard (5–100 m) windows — which are clean on this climb.

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: Ranked 2026-09-05 (D27, inventory authority): OS Open Roads carries the route as public road (100% covered, 0% restricted), which answers the OSM audit question (barrier gate without an access tag). A barrier gate without an access tag sits on the route; gates on public roads are usually seasonal — check on the ground.

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

Load the interactive map

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

Topo (contours) Vector   © OpenStreetMap contributors · topo tiles © OpenTopoMap (CC-BY-SA) · vector tiles OpenFreeMap

Profile

The map, 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

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/wales/dtm_1m/wg_del_28_284277_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_284278_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_284279_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_285277_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_285278_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_285279_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_286277_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_286278_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_286279_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_287277_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_287278_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_287279_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_288277_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_288278_20220314dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_28_288279_20220314dtm.tif"
  ],
  "calculated_at": "2026-09-05T05:58:36+00:00",
  "road_source": "OpenStreetMap (local PBF extract)",
  "road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
  "osm_pbf_path": "data/cache/pbf/wales-2026-08-11.osm.pbf",
  "osm_snapshot": "2026-08-10T20:21:40Z",
  "run_id": "summit-260905-summit-wales-wales-2026-08-11",
  "elevation_provider": "Welsh Government",
  "elevation_dataset": "Welsh Government LiDAR 1m DTM (2020-2023)",
  "elevation_licence": "Open Government Licence v3 \u2014 \u00a9 Crown copyright Welsh Government",
  "elevation_catalogue_layer": "geonode:welsh_government_lidar_tile_catalogue_2020_2023",
  "elevation_tile_ids": [
    "wg_del_28_284277_20220314dtm.tif",
    "wg_del_28_284278_20220314dtm.tif",
    "wg_del_28_284279_20220314dtm.tif",
    "wg_del_28_285277_20220314dtm.tif",
    "wg_del_28_285278_20220314dtm.tif",
    "wg_del_28_285279_20220314dtm.tif",
    "wg_del_28_286277_20220314dtm.tif",
    "wg_del_28_286278_20220314dtm.tif",
    "wg_del_28_286279_20220314dtm.tif",
    "wg_del_28_287277_20220314dtm.tif",
    "wg_del_28_287278_20220314dtm.tif",
    "wg_del_28_287279_20220314dtm.tif",
    "wg_del_28_288277_20220314dtm.tif",
    "wg_del_28_288278_20220314dtm.tif",
    "wg_del_28_288279_20220314dtm.tif"
  ],
  "elevation_capture_dates": [
    "14-03-2022"
  ],
  "route_summit_trim_m": 1484.9,
  "route_summit_trim_loss_m": 157.4,
  "climb_origin": "discovered",
  "license": "ODbL-1.0",
  "license_url": "https://howsteep.org/licensing"
}