Improve the data
What Ski Resort Stats Actually Mean
Trail counts, acres, and lift strings as they sit in ski_areas_analyzed.parquet, not as brochures print them.
Brochures sell a story. This file stores mapped objects. downhill_trails is a count of tagged piste ways. skiable_terrain_acres is area from the analyzed polygon. lift_types is a parsed string of aerialway counts. Vertical is often empty. Bristol Mountain, way 320434895, is the same hill as the pipeline post. Use it as the unit. If a number is missing here, the pipeline did not have it. The atlas will not fill it from a press kit.
Bristol on the wiki winter map. Stats come from this geometry.
Step 1. Trail count is objects, not named runs
OSM mappers split a named trail when the difficulty changes, when a cat-track peels off, or when two ways share a name. Bristol’s analyzed row currently reports 39 downhill trails. The extract parquet had 43 piste rows before analysis. Those two numbers are not a bug you hide. They are the difference between raw ways and the analyzed set. Marketing “26 trails” is a third counting rule. Pick one and stay with it.
Bristol difficulty buckets on the analyzed row.
Step 2. Acres follow the polygon
The 3 Valleys currently leads this file at about 12,127 mapped acres and 1,648 downhill trails, OSM id 45117869. Chapman Hill is a municipal rec area with four trails. Both rows use the same acre field. Aiguille du Midi (Chamonix) sits near 5,096 acres with 9 downhill trails in this extract: a huge polygon and almost no tagged piste ways. That is a mapping shape, not a ranking of “best terrain.”
Top acres in the current S3 parquet.
Step 3. Size plates on trail counts
The site buckets downhill areas as small (<10 trails), medium (10–29), large (30–99), and mega (100+). Most of the file is small: 0 rows. Mega is 0. Bristol’s 39 trails is large on that plate. The wiki-copy job in the data repo still treats 39 as a short paragraph. Do not mix those two rules when you quote a size.
Trail-count plates, same breaks as the print atlas.
Step 4. Lifts are a string you can parse
Chair lifts dominate the tagged total. Platters, magic carpets, T-bars, and drag lifts still outnumber gondolas. A hill with two carpets and a chair is a beginner day. A hill with a gondola and no carpets is not. Read lift_types before you argue about “lift-served acres.”
Parsed from lift_types on downhill rows.