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

Hill Road

1187.1 m · gain 114.2 m · overall 9.6% · Pontlottyn · Caerffili - Caerphilly

Shape: stepped — 45% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 366 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.

Gradient ladder what do windows mean?

Window	Maximum	Located at
2 m (diagnostic)	24.9%	470–472 m
3 m (diagnostic)	23.3%	386–389 m
5 m	22.4%	384–389 m
10 m	21.9%	379–389 m
20 m	21.4%	369–389 m
25 m	21.6%	364–389 m
50 m	20.9%	354–404 m
100 m	19.9%	348–448 m

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 Road 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_310205_20210227dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_10_310206_20210227dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_10_311205_20210227dtm.tif",
    "data/cache/wales/dtm_1m/wg_del_10_311206_20210227dtm.tif"
  ],
  "calculated_at": "2026-08-12T09:10:40+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_310205_20210227dtm.tif",
    "wg_del_10_310206_20210227dtm.tif",
    "wg_del_10_311205_20210227dtm.tif",
    "wg_del_10_311206_20210227dtm.tif"
  ],
  "elevation_capture_dates": [
    "27-02-2021"
  ],
  "climb_origin": "discovered",
  "notes": "Coarse pass: max 17.6% over 200 m (Terrain 50), gain 50.7 m over 294 m way. EXTENDED by graph walk: +6 segment(s) at base, +6 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. DEDUPE: absorbed 2 overlapping proposal(s): discovered-lane-51-7473-3-2885, discovered-lane-51-7482-3-2895 ADOPTED (notable slice 2026-08-11): clean-steep."
}