Adams Street to Cerrig yr Hafan
8383.0 m · net rise 379.5 m · total ascent 432.3 m · overall 4.5% · confidence: needs confirmation
Shape: sustained — 29% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 71 m.
Found purely from mapping and LiDAR data, and not yet matched against books, race records or lists — it may be well known to locals under a name we've never heard. It was cross-checked against the OS road network, surface models and map tags, but 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 you know this road, tell us what you found — photographs, corrections and local knowledge all welcome; the map links below let you scout it first.
needs review short_window_divergence — treat short-window maxima here as provisional.
≈ Overhead cover (tree canopy or structures) spans 26% 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 — the flag does not say whether the true value is higher or lower. Longer windows average over more clean ground and are steadier.
Gradient ladder what do windows mean?
| Window | Maximum | Located at | |
|---|---|---|---|
| 2 m (diagnostic) | 46% | 417–419 m | |
| 3 m (diagnostic) | 40% | 416–419 m | |
| 5 m | 28% | 414–419 m | |
| 10 m | 18% | 395–405 m | |
| 20 m | 15.4% | 399–419 m | |
| 25 m | 14.5% | 395–420 m | |
| 50 m | 13.4% | 322–372 m | |
| 100 m | 11.4% | 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
This climb's data: OCL JSON — the full gradient ladder, quality flags and provenance in the OpenClimb Ladder format.
Ridden it, or know better? Submit data for this climb no account needed
© 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_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": "2026-08-13T02:11:00+00:00",
"road_source": "wales-discovered-adopted-routes/discovered-lane-52-4923-3-8902.geojson",
"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",
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"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",
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"wg_del_22_273290_20220114dtm.tif",
"wg_del_23_265288_20220117dtm.tif",
"wg_del_23_265289_20220117dtm.tif",
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],
"elevation_capture_dates": [
"14-01-2022",
"17-01-2022"
],
"route_summit_trim_m": 2866.7,
"route_summit_trim_loss_m": 54.1,
"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)'."
}