Roads: no bridge/tunnel rendering, and the attribute is not imported #18

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opened 2026-08-01 19:12:55 +00:00 by art-bot · 0 comments

art-bot commented

2026-08-01 19:12:55 +00:00

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All three sources carry it — Iceland einingvegakerfis (1=road, 2=bridge, 3=ford,
4=tunnel, 6=mountain pass, 7=ferry), Sweden Bro_och_tunnel_Konstruktion, Poland
POLOZENIE — and none of it is imported, because the style has no underpass/overpass draw
ordering to consume it. Adding the column alone would put bytes in every tile for a
rendering that does not exist.

Adding the attribute and the ordering is one job, not two. Doing it means: a shared
column on the roads contract in conf/common.yaml, three per-country mappings, and a
style that splits each road class into below/at/above-grade layers ordered so that a tunnel
passes under and a bridge over.

Worth weighing against the fact that z14 is the current ceiling — at z14 the visual payoff
is modest, and it grows if the ceiling ever rises. docs/geo-primer.md records this as a
knowing gap under "layer order", and that note should be updated if this is done.

Note that Iceland's einingvegakerfis also carries ferries (7), which is the subject of
#6 — the two would be imported from the same attribute, so consider doing them together.

All three sources carry it — Iceland `einingvegakerfis` (1=road, 2=bridge, 3=ford, 4=tunnel, 6=mountain pass, 7=ferry), Sweden `Bro_och_tunnel_Konstruktion`, Poland `POLOZENIE` — and none of it is imported, because the style has no underpass/overpass draw ordering to consume it. Adding the column alone would put bytes in every tile for a rendering that does not exist. **Adding the attribute and the ordering is one job, not two.** Doing it means: a shared column on the `roads` contract in `conf/common.yaml`, three per-country mappings, and a style that splits each road class into below/at/above-grade layers ordered so that a tunnel passes under and a bridge over. Worth weighing against the fact that z14 is the current ceiling — at z14 the visual payoff is modest, and it grows if the ceiling ever rises. `docs/geo-primer.md` records this as a knowing gap under "layer order", and that note should be updated if this is done. Note that Iceland's `einingvegakerfis` also carries **ferries** (7), which is the subject of #6 — the two would be imported from the same attribute, so consider doing them together.