Route Des Alpes
2392.1 m · gain 136.3 m · overall 5.7% · Cwmllwydrew · Caerdydd - Cardiff
Shape: stepped — 51% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 110 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 52% 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) | ≈54.3% | 112–114 m | under overhead cover terrain reads 68.7% at 207–209 m across a structure — excluded |
| 3 m (diagnostic) | ≈47.0% | 92–95 m | under overhead cover terrain reads 58.0% at 206–209 m across a structure — excluded |
| 5 m | ≈39.2% | 93–98 m | under overhead cover terrain reads 51.9% at 205–210 m across a structure — excluded |
| 10 m | ≈34.5% | 92–102 m | under overhead cover terrain reads 37.5% at 200–210 m across a structure — excluded |
| 20 m | ≈30.8% | 90–110 m | under overhead cover |
| 25 m | ≈31.0% | 89–114 m | under overhead cover |
| 50 m | ≈23.9% | 64–114 m | under overhead cover terrain reads 24.4% at 267–317 m across a structure — excluded |
| 100 m | ≈17.4% | 14–114 m | under overhead cover terrain reads 18.6% at 262–362 m across a structure — excluded |
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
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_2_309183_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_2_309184_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_3_309182_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_3_310182_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_3_310183_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_3_310184_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_3_311182_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_3_311183_20201125dtm.tif",
"data/cache/wales/dtm_1m/wg_del_3_311184_20201125dtm.tif"
],
"calculated_at": "2026-08-12T09:11:15+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_2_309183_20201125dtm.tif",
"wg_del_2_309184_20201125dtm.tif",
"wg_del_3_309182_20201125dtm.tif",
"wg_del_3_310182_20201125dtm.tif",
"wg_del_3_310183_20201125dtm.tif",
"wg_del_3_310184_20201125dtm.tif",
"wg_del_3_311182_20201125dtm.tif",
"wg_del_3_311183_20201125dtm.tif",
"wg_del_3_311184_20201125dtm.tif"
],
"elevation_capture_dates": [
"26-11-2020"
],
"climb_origin": "discovered",
"notes": "Coarse pass: max 18.0% over 200 m (Terrain 50), gain 128.2 m over 2266 m way. EXTENDED by graph walk: +2 segment(s) at base, +1 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (notable slice 2026-08-11): qualified-steep."
}