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

Hill Street

1696.9 m · gain 146.0 m · overall 8.6% · Cwm Ysgwydd-gwyn · Caerffili - Caerphilly

Shape: sustained — 41% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 175 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.

≈ Overhead cover (tree canopy or structures) spans 43% 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?

Window	Maximum	Located at
2 m (diagnostic)	≈34.0%	635–637 m	under overhead cover terrain reads 36.4% at 603–605 m across terrain that holds no road surface (dense canopy, no bench) — excluded
3 m (diagnostic)	≈32.6%	634–637 m	under overhead cover
5 m	29.1%	7–12 m
10 m	28.3%	17–27 m
20 m	28.1%	7–27 m
25 m	27.9%	7–32 m
50 m	25.9%	5–55 m
100 m	19.1%	3–103 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

Hill Street LiDAR hillshade map with contours

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_10_312201_20210227dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_10_312202_20210227dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_10_313201_20210227dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_10_313202_20210227dtm.tif"
  ],
  "calculated_at": "2026-08-12T09:10:41+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_10_312201_20210227dtm.tif",
    "wg_del_10_312202_20210227dtm.tif",
    "wg_del_10_313201_20210227dtm.tif",
    "wg_del_10_313202_20210227dtm.tif"
  ],
  "elevation_capture_dates": [
    "27-02-2021"
  ],
  "climb_origin": "discovered",
  "notes": "Coarse pass: max 12.5% over 200 m (Terrain 50), gain 26.2 m over 286 m way. EXTENDED by graph walk: +0 segment(s) at base, +2 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. DEDUPE: absorbed 1 overlapping proposal(s): cefn-road ADOPTED (notable slice 2026-08-11): qualified-steep."
}