Poland's stations have no importance-3 rung: z9 empty, 3 225 stations at z10 #68

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opened 2026-08-06 19:00:41 +00:00 by art-bot · 0 comments

art-bot commented

2026-08-06 19:00:41 +00:00

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Follow-up from the #66 review (per-country transit stops). #66 merges as-is; this is the gap it leaves.

What

Poland's stations partition has no importance = 3 rung, so the z9 filter empties the layer entirely, and everything lands on rung 2 at z10.

zoom	pl	se	fi
z9	0	485	0
z10	3 225	964	383
z11	3 225	964	383

Two symptoms, one cause:

z10/z11 is crowded. Poland draws every rail halt in the country — 3 187 stations plus 38 metro — at a zoom that shows the whole country. That is 3.3× Sweden on a comparable area.
z9 is empty. Sweden shows its 485 major stations at z9; Poland and Finland show nothing, because the zoom_filters cascade (z11: importance >= 2, z9: importance >= 3) leaves nothing to keep.

Breakdown at maxz:

 country |   mode   | importance | count
---------+----------+------------+-------
 pl      | tram     |          1 |   827
 pl      | metro    |          2 |    38
 pl      |          |          2 |  3187
 se      | tram     |          1 |   309
 se      |          |          1 |   786
 se      | metro    |          2 |   100
 se      | commuter |          2 |    25
 se      |          |          2 |   354
 se      | commuter |          3 |    30
 se      |          |          3 |   455

Sweden fills three rungs because Trafikverket says outright whether a site handles passengers (ResUtbyte) and what kind of site it is (PlTyp).

Why the obvious source does not work

BDOT10k's own discriminator was examined in #66 and rejected, correctly. The class is stacja lub przystanek kolejowy (station or halt) and the per-object hints contradict reality: Białystok, Katowice, Poznań Główny and Gdynia Główna all carry skrotkartograficzny = 'p. kol.' — the halt mark. 1 055 rows have no skrot at all, and 433 p. kol. rows also carry the "stacja kolejowa - wg danych PKP PLK" note. Grading on it would demote the country's biggest stations. See the reasoning next to the query in conf/plmap.yaml.

So rung 3 needs a signal from somewhere other than the object's own attributes.

Candidate approaches

Name morphology. Główny / Centralna / Główna in nazwa is a strong marker of a city's principal station and is carried by the source. Cheap, and it is the source's own text rather than an external judgement.
Administrative rank. Join against the voivodeship-capital / powiat-seat set and promote the principal station in each. Needs a settlement source Poland already has or can get from PRG.
Platform-point count. The rail branch already clusters platform points per station (Warszawa Zachodnia ×8, max 8 in the data). Station size correlates with point count, though 8 is a thin ceiling to grade on.

Likely some combination — name morphology is the cheapest first cut and can be measured against a hand-checked list of the ~50 stations that should appear at z9.

Note on Finland

Finland has the same empty z9 rung, for its own reason (MTK says only that a railway traffic site is here; having a name in the register is the one available signal, so named sites take 2 and unnamed 1). It is already documented in conf/fimap.yaml and docs/country-finland.md. Whatever shape the Poland fix takes, it is worth checking whether it generalizes — the shared stations contract is supposed to mean the same thing in every country, and right now rung 3 means "Sweden".

Follow-up from the #66 review (per-country transit stops). #66 merges as-is; this is the gap it leaves. ## What Poland's `stations` partition has no `importance = 3` rung, so the z9 filter empties the layer entirely, and everything lands on rung 2 at z10. | zoom | pl | se | fi | |---|---|---|---| | z9 | **0** | 485 | **0** | | z10 | **3 225** | 964 | 383 | | z11 | 3 225 | 964 | 383 | Two symptoms, one cause: - **z10/z11 is crowded.** Poland draws every rail halt in the country — 3 187 stations plus 38 metro — at a zoom that shows the whole country. That is 3.3× Sweden on a comparable area. - **z9 is empty.** Sweden shows its 485 major stations at z9; Poland and Finland show nothing, because the `zoom_filters` cascade (`z11: importance >= 2`, `z9: importance >= 3`) leaves nothing to keep. Breakdown at maxz: ``` country | mode | importance | count ---------+----------+------------+------- pl | tram | 1 | 827 pl | metro | 2 | 38 pl | | 2 | 3187 se | tram | 1 | 309 se | | 1 | 786 se | metro | 2 | 100 se | commuter | 2 | 25 se | | 2 | 354 se | commuter | 3 | 30 se | | 3 | 455 ``` Sweden fills three rungs because Trafikverket says outright whether a site handles passengers (`ResUtbyte`) and what kind of site it is (`PlTyp`). ## Why the obvious source does not work BDOT10k's own discriminator was examined in #66 and rejected, correctly. The class is `stacja lub przystanek kolejowy` (station **or** halt) and the per-object hints contradict reality: Białystok, Katowice, Poznań Główny and Gdynia Główna all carry `skrotkartograficzny = 'p. kol.'` — the *halt* mark. 1 055 rows have no `skrot` at all, and 433 `p. kol.` rows also carry the "stacja kolejowa - wg danych PKP PLK" note. Grading on it would demote the country's biggest stations. See the reasoning next to the query in `conf/plmap.yaml`. So rung 3 needs a signal from somewhere other than the object's own attributes. ## Candidate approaches - **Name morphology.** `Główny` / `Centralna` / `Główna` in `nazwa` is a strong marker of a city's principal station and is carried by the source. Cheap, and it is the source's own text rather than an external judgement. - **Administrative rank.** Join against the voivodeship-capital / powiat-seat set and promote the principal station in each. Needs a settlement source Poland already has or can get from PRG. - **Platform-point count.** The rail branch already clusters platform points per station (`Warszawa Zachodnia` ×8, max 8 in the data). Station size correlates with point count, though 8 is a thin ceiling to grade on. Likely some combination — name morphology is the cheapest first cut and can be measured against a hand-checked list of the ~50 stations that should appear at z9. ## Note on Finland Finland has the same empty z9 rung, for its own reason (MTK says only that a railway traffic site is *here*; having a name in the register is the one available signal, so named sites take 2 and unnamed 1). It is already documented in `conf/fimap.yaml` and `docs/country-finland.md`. Whatever shape the Poland fix takes, it is worth checking whether it generalizes — the shared `stations` contract is supposed to mean the same thing in every country, and right now rung 3 means "Sweden".

art-bot referenced this issue

2026-08-06 19:01:07 +00:00

#64 per-country transit stops: Warsaw metro from BDOT10k OIKM_P (official, with badge), Kraków/Łódź tram, FI Digiroad tram #66