Add railroad tracks

[claysmalley]

Closes #101.

At the moment, this is a draft and only implements railway=rail. Once finished, this PR will implement all other values of railway surfaced by OpenMapTiles:

• rail
• subway
• light_rail
• tram
• monorail
• funicular
• narrow_gauge
• preserved

[claysmalley]

Changed to gray:

[ZeLonewolf]

I think the monochrome makes more sense than yellow with the conflict with toll roads. When we get to station POIs, I'm thinking they should be purple like airports, so that the conceptual transit layer sits at a common color. Also, not sure that we want to show rail at lower zooms. Google starts showing rail in hairline visibility at the equivalent to our z10 for example.

[michaelblyons]

I'm for having the rails themselves purple as well, but perhaps desaturated relative to the POIs. The grey ones kind of look like minor roads at low zoom.

[wmisener]

I agree that the gray looks too similar to minor roads, and that having a unified transport color is desirable, and so far that's purple. Any purple hue for rail lines might have to be checked against the admin boundaries halo to make sure it doesn't clash.

[claysmalley]

I'm hesitant to assign purple to railroads because the majority of railroad lines in North America don't carry passenger trains, and there's not much precedent in US cartographic tradition for purple railroads. I'd rather just keep them grayscale, and reserve purple for stations.

[claysmalley]

If busways are rendered in purple in #477, it may set a precedent for public transit railways (subway, tram, funicular, etc.) to be purple as well.

[claysmalley]

Added narrow gauge railways, with slightly thinner lines and dashes a little closer together than railway=rail.

[1ec5]

Remember to update scripts/taginfo_template.json with any tags for which this PR would introduce noteworthy treatment.

[claysmalley]

Now with bridge casing:

[claysmalley]

In all, this adds 214 layers, increasing the layer count from 620 to 834. I could probably reduce the count by using data-driven styling for the fill, but Maplibre does not yet support data-driven styling for dash arrays, so unfortunately the tie pattern is going to give this a high layer count for the time being.

[claysmalley]

I managed to combine railway fill into just a few layers, bringing the added layer count to 102. The layer count in main has since been reduced to 615, and this PR will make it 717.

[claysmalley]

615 → 701, +86. I think that's the best I can optimize this without support for Maplibre expressions in dash arrays.

[ZeLonewolf]

Are there any lessons learned from this PR that can be applied to the rest of the road layer?

[claysmalley]

Yeah, and I plan on working on that next 😅

In particular, styling things with expressions wherever possible makes it easier to convert everything else to expressions when new features are supported. So I think converting as many parameters of the road styling as possible into one big expression would be helpful.

[ZeLonewolf]

Awesome!

Do we have an open issue for the dashed array expressions in Americana that can be linked to the maplibre issue as a blocker?

[claysmalley]

Tracked in #526.

[ZeLonewolf]

This looks pretty good to me, visually. There is maybe a some exploration that can happen to find a way to draw a better visual distinction from the road network, but I think the style choice feels right in terms of the line style with the cross-ties representing rail.

Rail going over/under objects seems to make sense also. In this case where a rail goes from above ground, to under a building, to underground, the map makes sense:

If someone has an example of rail going OVER a building, we should examine that case to see if the ordering still looks right

Overall a 👍 from me with one minor comment in the code, but like to have more eyes on this.

[1ec5]

If someone has an example of rail going OVER a building, we should examine that case to see if the ordering still looks right

The AirTrain over the International Terminal at SFO:

[claysmalley]

railway=preserved is now rendered identically to railway=rail, pending OpenMapTiles support of railway:preserved=yes.

[1ec5]

I’m on board with these changes! Some of the screenshots of Americana on the wiki and elsewhere are going to look really outdated now that the actual style fills in the gaps with this intricate line work.