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

Ponthir Road

242.5 m · gain 16.9 m · overall 7.0% · Caerllion · Casnewydd - Newport

Shape: sustained — 36% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 38 m.

Documented on the ground — tag: 20% (2026). Signs get repainted and tags get retagged, so the date is part of the fact; on no cycling list we know of.

Gradient ladder what do windows mean?

Window	Maximum	Located at
2 m (diagnostic)	14.6%	52–54 m
3 m (diagnostic)	13.7%	51–54 m
5 m	13.0%	71–76 m
10 m	12.6%	57–67 m
20 m	12.4%	56–76 m
25 m	12.4%	51–76 m
50 m	10.5%	30–80 m
100 m	8.5%	36–136 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

Ponthir 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_5_333191_20201201dtm.tif"
  ],
  "calculated_at": "2026-08-12T09:12:01+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_5_333191_20201201dtm.tif"
  ],
  "elevation_capture_dates": [
    "01-12-2020"
  ],
  "climb_origin": "osm_incline",
  "signed_gradient_pct": 20.0,
  "signed_source": "OSM incline tag 20% (editors=1, first tagged 2021-10-04)",
  "notes": "Promoted automatically from triage verdict=validated. EXTENDED by graph walk: +4 segment(s) at base, +1 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting."
}