High Street Hill Road
1503.0 m · net rise 133.4 m · total ascent 139.8 m · overall 8.9% · evidence quality B (good) · Windsor · Massachusetts · share
Shape: sustained — 38% of the climbing sits in a quarter of the distance; longest continuous stretch at 10%+ is 260 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 state road inventory, OpenStreetMap and the point-cloud evidence for a graded road bed, 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 66% 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) | ≈37% | 491–493 m | under overhead cover terrain reads 54.5% at 914–916 m across a structure — excluded |
| 3 m (diagnostic) | ≈33% | 491–494 m | under overhead cover terrain reads 51.6% at 914–917 m across a structure — excluded |
| 5 m | ≈29% | 922–927 m | under overhead cover terrain reads 41.2% at 913–918 m across a structure — excluded |
| 10 m | ≈26% | 880–890 m | under overhead cover terrain reads 30.1% at 913–923 m across a structure — excluded |
| 20 m | ≈22.0% | 870–890 m | under overhead cover terrain reads 25.1% at 910–930 m across a structure — excluded |
| 25 m | ≈21.1% | 865–890 m | under overhead cover terrain reads 22.9% at 905–930 m across a structure — excluded |
| 50 m | ≈19.0% | 340–390 m | under overhead cover terrain reads 19.3% at 877–927 m across a structure — excluded |
| 100 m | ≈17.6% | 285–385 m | under overhead cover terrain reads 17.9% at 913–1013 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
This climb's data: OCL JSON — the full gradient ladder, quality flags and provenance in the OpenClimb Ladder format.
Surface: unpaved throughout, according to each state's road inventory.
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 · aerial imagery USGS (public domain)
Profile
The 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 | USGS 3DEP (The National Map) — USGS 3DEP 1 m DEM, MA_Western_B24 (collected 2023-24) |
|---|---|
| Resolution / CRS | 1.0 m grid, EPSG:26918; sampled every 1.0 m, bilinear interpolation |
| Tiles | x66y471 |
| Road centreline | OpenStreetMap (local PBF extract) |
| Quality status | evidence quality B; review flags: short window divergence |
| Analysis | OCL 0.1.0, analysis 0.1.0, run remeasure-260920-us, calculated 2026-09-21 |
Provenance
{
"analysis_version": "0.1.0",
"run_manifest": {
"manifest_version": "1",
"code_git_sha": "cd1381c557ec0196a6c481fc125290b249b285c2",
"code_git_dirty": "true",
"analysis_version": "0.1.0",
"analysis_config_digest": "sha256:faa4beed0662d2f6",
"python": "3.14.4",
"numpy": "2.5.3",
"rasterio": "1.5.1",
"pyproj": "3.8.0",
"laspy": "2.7.0",
"shapely": "2.1.2",
"pyosmium": "4.3.1",
"libosmium": "2.23.1",
"gdal": "3.12.4",
"proj": "9.8.1",
"run_id": "remeasure-260920-us",
"road_pbf": "batch-usa-ma-chunk003.pbf",
"region_key": "usa-ma",
"crs": "EPSG:26918",
"elevation_provider_key": "usa3dep",
"authority": "usa-inventory",
"registry_pbf": "massachusetts-260822.osm.pbf",
"tile_index_snapshot": "sha256:17002c76ed457f82"
},
"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:26918",
"elevation_resolution_m": 1.0,
"elevation_tiles": [
"data/cache/usa/ma/USGS_1M_18_x66y471_MA_Western_B24.tif"
],
"calculated_at": "2026-09-21T02:35:39+00:00",
"road_source": "OpenStreetMap (local PBF extract)",
"road_attribution": "\u00a9 OpenStreetMap contributors, ODbL",
"osm_pbf_path": "output/remeasure-260920/us/batch-usa-ma-chunk003.pbf",
"osm_snapshot": "",
"run_id": "remeasure-260920-us",
"elevation_provider": "USGS 3DEP (The National Map)",
"elevation_licence": "Public domain \u2014 USGS 3DEP 1 m DEM, courtesy of the U.S. Geological Survey",
"elevation_dataset": "USGS 3DEP 1 m DEM, MA_Western_B24 (collected 2023-24)",
"elevation_tile_ids": [
"x66y471"
],
"climb_origin": "discovered",
"canopy_source": {
"kind": "ept_corridor_max_return",
"ept_source": "https://usgs-lidar-public.s3-us-west-2.amazonaws.com/USGS_LPC_MA_ME_MA_QL2_UTM18_L1_2015_LAS_2018",
"ept_crs": "EPSG:3857",
"station_coverage": 0.997,
"cell_ground_m": 1.0,
"nodes_failed": 0,
"window_coverage": {
"5": 1.0,
"10": 1.0,
"20": 1.0,
"25": 1.0
}
},
"structure_own_ways": "none \u2014 the route carried no way list; own decks unmasked",
"carriageway": {
"stations": 66,
"stations_resolved": 66,
"width_median_m": 5.62,
"width_p10_m": 3.12,
"width_min_m": 1.75,
"width_max_m": 9.0,
"bounded_share": 0.182,
"unbounded_share": 0.818,
"confidence_median": 0.0,
"width_median_bounded_m": 5.0,
"window_m": [
865.0,
890.0
],
"width_at_max25_m": 6.38,
"window_stations": 6,
"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,
"break_min_m": 0.3,
"stations_failed": 0,
"hedge_to_hedge": {
"status": "unavailable \u2014 no DSM raster (surface model absent or point-cloud only, which cannot serve off-line samples)"
}
},
"unmapped_bridge_span": {
"start_m": 753.0,
"end_m": 916.0,
"span_m": 163.0,
"floor_at_m": 807.0,
"depth_m": 9.2,
"drop_m": 2.6,
"surface": "raw",
"window_start_m": 865.0,
"window_end_m": 890.0,
"gap_m": 0.0,
"unstable": false,
"perturbation_hits": 3,
"note": "The ground falls 3 m below the road between 753 m and 916 m \u2014 9 m below the straight line joining the profile either side of it \u2014 and climbs back to that line, with the steepest 25 m at 865 m. That is a ravine under a deck OSM does not tag as a bridge, so no mask fired. Re-measure with mask_ranges_m over the span before this maximum stands (unmapped-bridge-span, Peter 2026-09-20)."
},
"remeasured": {
"on": "2026-09-21",
"why": "corpus re-measure 2026-09-21: a mask that exists today reaching a page published before it did; fallers only (Peter: fold the fallers)",
"published_max25_pct": 22.93,
"max25_pct": 21.08
},
"license": "ODbL-1.0",
"license_url": "https://howsteep.org/licensing"
}