highway=bus_guideway layering, tunnels, covered, bridges

[sladen]

Per request @kocio-pl in /issues/2965#issuecomment-448795111:

for highway=bus_guideway, the following are not rendered:

• layer=0 (ie. under bridge=yes; layer=1) https://www.openstreetmap.org/way/54965900#map=17/-34.89753/138.61934
• layer=-1 (ie. under bridge=yes) https://www.openstreetmap.org/way/55053642#map=18/-34.89048/138.63145
• tunnel=yes* https://www.openstreetmap.org/way/545944857#map=16/-34.92069/138.61394
• bridge=yes https://www.openstreetmap.org/way/420096851#map=17/51.888/-0.46729
• bridge=viaduct https://www.openstreetmap.org/way/92924790#map=18/52.31489/-0.05584
• covered=yes https://www.openstreetmap.org/way/656244701#map=19/33.92338/-118.34427

Ideally these would be rendered as per a railway. There were some historical locations in Essen and Mannheim where highway=bus_guideway and railway=tram would have shared the same physical space, but these appear to disappeared about when OSM came into existance.

[sladen]

Essen example:

• highway=bus_guideway; railway=tram https://www.openstreetmap.org/way/81149695#map=19/51.45231/7.02779

As an aside, but for completeness… This was the former Mannheim example, it would appear to have been paved over as a normal tram/bus-only service road:

• https://www.openstreetmap.org/way/204347211#map=19/49.48900/8.51716

Ideally the tram rendering should be on top of the bus_guideway.

[imagico]

Going to keep this open as the aggregate issue for all the highway=bus_guideway layering issue and closing #2489 and #2897 instead.

The solution for this is IMO to include highway=bus_guideway in the roads layers. It seems that would depend on a database reload because it would require defining a z_order for highway=bus_guideway - see

openstreetmap-carto/openstreetmap-carto.lua

Lines 188 to 214 in a2077c0

	local roads_info = {
	highway = {
	motorway = {z = 380, roads = true},
	trunk = {z = 370, roads = true},
	primary = {z = 360, roads = true},
	secondary = {z = 350, roads = true},
	tertiary = {z = 340, roads = false},
	residential = {z = 330, roads = false},
	unclassified = {z = 330, roads = false},
	road = {z = 330, roads = false},
	living_street = {z = 320, roads = false},
	pedestrian = {z = 310, roads = false},
	raceway = {z = 300, roads = false},
	motorway_link = {z = 240, roads = true},
	trunk_link = {z = 230, roads = true},
	primary_link = {z = 220, roads = true},
	secondary_link = {z = 210, roads = true},
	tertiary_link = {z = 200, roads = false},
	service = {z = 150, roads = false},
	track = {z = 110, roads = false},
	path = {z = 100, roads = false},
	footway = {z = 100, roads = false},
	bridleway = {z = 100, roads = false},
	cycleway = {z = 100, roads = false},
	steps = {z = 90, roads = false},
	platform = {z = 90, roads = false}
	},