Mangatangi Hill Road (ARA drive)
3757.0 m · net rise 304.5 m · total ascent 357.6 m · overall 8.1% · evidence quality B (good) · Franklin · Waikato · share
Shape: sustained — 43% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 376 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 LINZ's Topo50 road centrelines, OpenStreetMap and a second terrain model, 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.
≈ Overhead cover (tree canopy or structures) spans 53% 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) | ≈48% | 329–331 m | under overhead cover terrain reads 87.0% at 2738–2740 m across a structure — excluded |
| 3 m (diagnostic) | ≈40% | 329–332 m | under overhead cover terrain reads 77.9% at 3739–3742 m across a structure and terrain that holds no road surface (dense canopy, no bench) — excluded |
| 5 m | ≈33% | 3622–3627 m | under overhead cover terrain reads 70.8% at 3256–3261 m across a structure — excluded |
| 10 m | ≈27% | 3622–3632 m | under overhead cover terrain reads 55.6% at 3252–3262 m across a structure and terrain that holds no road surface (dense canopy, no bench) — excluded |
| 20 m | ≈21.8% | 1977–1997 m | under overhead cover terrain reads 45.2% at 3250–3270 m across a structure and terrain that holds no road surface (dense canopy, no bench) — excluded |
| 25 m | ≈20.8% | 1977–2002 m | under overhead cover terrain reads 38.1% at 3250–3275 m across a structure and terrain that holds no road surface (dense canopy, no bench) — excluded |
| 50 m | ≈17.2% | 2612–2662 m | under overhead cover terrain reads 27.1% at 3363–3413 m across a structure — excluded |
| 100 m | ≈16.1% | 2606–2706 m | under overhead cover terrain reads 21.2% at 3349–3449 m across a structure and terrain that holds no road surface (dense canopy, no bench) — excluded |
may continue beyond end 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.
Surface: unpaved throughout, according to LINZ Topo50 road centrelines.
Access: Listed 2026-09-28 (inventory hunt wave 1): road audit — barrier gate (no access tag) 0.0 m off route; barrier gate (no access tag) 0.0 m off route; barrier gate (no access tag) 0.0 m off route. Never silently ranked or dropped (Peter, 2026-08-27).
Measured, not vetted. This page records what the laser record shows about the road's shape — nothing more. Nobody has necessarily ridden or inspected this road for the survey, and a page here is not a recommendation and no guarantee that the road is open, surfaced, rideable or safe. Gates, private sections, missing rights of way and hazards do not show up in elevation data. Check access and conditions on the ground and make your own judgment.
Ridden it, or know better? Submit data for this climb no account needed · Share this climb
Route colour = gradient over a 25 m window: <10% 10–20% 20–25% ≥25%
© OpenStreetMap contributors · topo tiles © OpenTopoMap (CC-BY-SA) · vector tiles OpenFreeMap
Profile
The map, profile and gradient chart share one position — move your pointer over them and the marker follows. Colors are the gradient bands; the shaded span is the steepest 25 m. Any 25 m figure is good to about a point either way (why).
Measurement card
| Elevation | LINZ nz-elevation — New Zealand 1 m DEM/DSM national LiDAR mosaic — Toitū Te Whenua Land Information New Zealand (LINZ), vertical datum NZVD2016 (LINZ documentation; not re-verified against a benchmark) |
|---|---|
| Resolution / CRS | 1.0 m grid, EPSG:2193; sampled every 1.0 m, bilinear interpolation |
| Tiles | BB33 |
| Road centreline | OpenStreetMap (local PBF extract) |
| Quality status | evidence quality B; caveated windows: canopy or structure, no bench excluded, no bench excluded min, structure excluded, structure excluded min, suppression unstable, texture excluded |
| Analysis | OCL 0.1.0, analysis 0.1.0, run nz-n3, calculated 2026-09-28 |
Provenance
{
"analysis_version": "0.1.0",
"run_manifest": {
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"code_git_sha": "f5ccc1713da600fbea2ba1433fb64f96644949ee",
"code_git_dirty": "false",
"analysis_version": "0.1.0",
"analysis_config_digest": "sha256:8c94015b54267da4",
"python": "3.14.4",
"numpy": "2.5.3",
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"pyproj": "3.8.0",
"laspy": "2.7.0",
"shapely": "2.1.2",
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"libosmium": "2.23.1",
"gdal": "3.12.4",
"proj": "9.8.1",
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"road_pbf": "block-batch-nz-n3.osm.pbf",
"region_key": "nz",
"crs": "EPSG:2193",
"elevation_provider_key": "nz-linz",
"tile_index": "stac",
"authority": "linz",
"registry_pbf": "new-zealand-2026-09-26.osm.pbf",
"tile_index_snapshot": "sha256:7959a7d1d462b1b3"
},
"sample_interval_m": 1.0,
"interpolation": "bilinear",
"smoothing": "none",
"gradient_windows_m": [
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],
"diagnostic_windows_m": [
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],
"elevation_crs": "EPSG:2193",
"elevation_resolution_m": 1.0,
"elevation_tiles": [
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],
"calculated_at": "2026-09-28T05:50:46+00:00",
"road_source": "OpenStreetMap (local PBF extract)",
"road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
"osm_pbf_path": "data/cache/pbf/block-batch-nz-n3.osm.pbf",
"osm_snapshot": "",
"run_id": "nz-n3",
"elevation_provider": "LINZ nz-elevation",
"elevation_licence": "CC BY 4.0 \u2014 Toit\u016b Te Whenua Land Information New Zealand \u2014 https://nz-elevation.s3.ap-southeast-2.amazonaws.com/LICENSE",
"elevation_dataset": "New Zealand 1 m DEM/DSM national LiDAR mosaic \u2014 Toit\u016b Te Whenua Land Information New Zealand (LINZ), vertical datum NZVD2016 (LINZ documentation; not re-verified against a benchmark)",
"elevation_tile_ids": [
"BB33"
],
"route_summit_trim_m": 2925.3,
"route_summit_trim_loss_m": 277.4,
"climb_origin": "discovered",
"seam_filled_samples": {
"count": 0,
"distances_m": []
},
"seam_filled_in_maximum": false,
"structure_own_ways": 1,
"suppression_unstable": [
10.0
],
"carriageway": {
"stations": 157,
"stations_resolved": 157,
"width_median_m": 4.5,
"width_p10_m": 2.25,
"width_min_m": 1.0,
"width_max_m": 12.0,
"bounded_share": 0.146,
"unbounded_share": 0.854,
"confidence_median": 0.0,
"width_median_bounded_m": 2.25,
"window_m": [
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],
"width_at_max25_m": 4.5,
"window_stations": 7,
"single_track": false,
"single_track_rule": "PROVISIONAL (2026-09-15): width_p10_m <= 3.0 m with bounded_share >= 0.6; recorded, not a rule",
"status": "ok",
"source": "dtm",
"station_m": 25.0,
"window_station_m": 5.0,
"halfwidth_m": 6.0,
"step_m": 0.25,
"level_tol_m": 0.12,
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"stations_failed": 0,
"hedge_to_hedge": {
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"width_median_m": 2.75,
"width_p10_m": 0.75,
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"unbounded_share": 0.045,
"confidence_median": 1.0,
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],
"width_at_max25_m": 4.75,
"window_stations": 7,
"status": "ok",
"source": "dsm",
"station_m": 25.0,
"window_station_m": 5.0,
"halfwidth_m": 6.0,
"step_m": 0.25,
"level_tol_m": 0.5,
"break_min_m": 0.3,
"stations_failed": 0
}
},
"license": "ODbL-1.0",
"license_url": "https://howsteep.org/licensing"
}