BETA — measurements and names under active refinement. Seen a sign, a gate, or a better name? Report it (photos welcome).

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Adams Street to Cerrig yr Hafan°

11249.7 m · gain 325.5 m · overall 2.9% · Cwm Twrch · Sir Ceredigion - Ceredigion

Shape: sustained — 34% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 71 m.

An unlisted find of this survey, on no list we know of. It was discovered by analysing LiDAR terrain data and cross-checked against the OS road network, surface models and map tags — but despite all that, 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 that someone is you, tell us what you found — photographs, corrections and local knowledge all welcome; the map links below let you scout it first.

° The name is provisional: this climb appears on no list we know of, so it was named from nearby map places. There is no evidence of local usage — (auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (52.4923, -3.8902)'). Corrections welcome.

≈ Overhead cover (tree canopy or structures) spans 20% of this route — detected by comparing the surface model (DSM, treetops and rooftops) against the terrain model (DTM, bare ground). Under cover the bare-ground model is built from fewer laser returns, so metre-scale readings can wobble; maxima whose window sits in a covered zone are marked ≈ below — less certain, not wrong. Longer windows average over more clean ground and are steadier.

Gradient ladder what do windows mean?

WindowMaximumLocated at
2 m (diagnostic)≈45.7%417–419 munder overhead cover terrain reads 61.5% at 10531–10533 m across a structure — excluded
3 m (diagnostic)≈40.5%416–419 munder overhead cover terrain reads 46.9% at 10531–10534 m across a structure — excluded
5 m≈28.5%414–419 munder overhead cover terrain reads 31.7% at 10531–10536 m across a structure — excluded
10 m22.2%10581–10591 m
20 m18.1%10574–10594 m
25 m16.9%10572–10597 m
50 m13.8%10549–10599 m
100 m11.4%319–419 m

may_start_earlier 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

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

Adams Street to Cerrig yr Hafan LiDAR hillshade map with contours

Profile

Adams Street to Cerrig yr Hafan elevation profile Adams Street to Cerrig yr Hafan rolling gradient profile

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_22_266288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_266289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_266290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_267288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_267289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_267290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_268288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_268289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_268290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_269288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_269289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_269290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_270288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_270289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_270290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_271288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_271289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_271290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_272288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_272289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_272290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_273288_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_273289_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_22_273290_20220114dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_23_265288_20220117dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_23_265289_20220117dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_23_265290_20220117dtm.tif"
  ],
  "calculated_at": "2026-08-12T09:08:29+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",
  "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_22_266288_20220114dtm.tif",
    "wg_del_22_266289_20220114dtm.tif",
    "wg_del_22_266290_20220114dtm.tif",
    "wg_del_22_267288_20220114dtm.tif",
    "wg_del_22_267289_20220114dtm.tif",
    "wg_del_22_267290_20220114dtm.tif",
    "wg_del_22_268288_20220114dtm.tif",
    "wg_del_22_268289_20220114dtm.tif",
    "wg_del_22_268290_20220114dtm.tif",
    "wg_del_22_269288_20220114dtm.tif",
    "wg_del_22_269289_20220114dtm.tif",
    "wg_del_22_269290_20220114dtm.tif",
    "wg_del_22_270288_20220114dtm.tif",
    "wg_del_22_270289_20220114dtm.tif",
    "wg_del_22_270290_20220114dtm.tif",
    "wg_del_22_271288_20220114dtm.tif",
    "wg_del_22_271289_20220114dtm.tif",
    "wg_del_22_271290_20220114dtm.tif",
    "wg_del_22_272288_20220114dtm.tif",
    "wg_del_22_272289_20220114dtm.tif",
    "wg_del_22_272290_20220114dtm.tif",
    "wg_del_22_273288_20220114dtm.tif",
    "wg_del_22_273289_20220114dtm.tif",
    "wg_del_22_273290_20220114dtm.tif",
    "wg_del_23_265288_20220117dtm.tif",
    "wg_del_23_265289_20220117dtm.tif",
    "wg_del_23_265290_20220117dtm.tif"
  ],
  "elevation_capture_dates": [
    "14-01-2022",
    "17-01-2022"
  ],
  "climb_origin": "discovered",
  "notes": "Coarse pass: max 8.7% over 200 m (Terrain 50), gain 294.5 m over 10791 m way. EXTENDED by graph walk: +4 segment(s) at base, +0 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (notable slice 2026-08-11): big-gain. AUTO-NAMED from gazetteer (hypothesis, unreviewed): was 'Discovered lane (52.4923, -3.8902)'.",
  "naming_note": "auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (52.4923, -3.8902)'"
}