Fix layering order for highway=construction by adding z-order for construction=* values

openstreetmap-carto.lua

@@ -216,7 +216,6 @@ local roads_info = {
         cycleway        = {z = 100, roads = false},
         steps           = {z = 90,  roads = false},
         platform        = {z = 90,  roads = false},
-        construction    = {z = 10,  roads = false}
     },
     railway = {
         rail            = {z = 440, roads = true},
@@ -237,6 +236,32 @@ local roads_info = {
         runway          = {z = 60,  roads = false},
         taxiway         = {z = 50,  roads = false},
     },
+    construction = {
+        motorway        = {z = 38, roads = true},
+        trunk           = {z = 37, roads = true},
+        primary         = {z = 36, roads = true},
+        secondary       = {z = 35, roads = true},
+        tertiary        = {z = 34, roads = false},
+        residential     = {z = 33, roads = false},
+        unclassified    = {z = 33, roads = false},
+        road            = {z = 33, roads = false},
+        living_street   = {z = 32, roads = false},
+        pedestrian      = {z = 31, roads = false},
+        raceway         = {z = 30, roads = false},
+        motorway_link   = {z = 24, roads = true},
+        trunk_link      = {z = 23, roads = true},
+        primary_link    = {z = 22, roads = true},
+        secondary_link  = {z = 21, roads = true},
+        tertiary_link   = {z = 20, roads = false},
+        service         = {z = 15, roads = false},
+        track           = {z = 11, roads = false},
+        path            = {z = 10, roads = false},
+        footway         = {z = 10, roads = false},
+        bridleway       = {z = 10, roads = false},
+        cycleway        = {z = 10, roads = false},
+        steps           = {z = 9,  roads = false},
+        platform        = {z = 9,  roads = false},
+    },
     boundary = {
         administrative  = {z = 0,  roads = true}
     },
@@ -256,6 +281,9 @@ function z_order(tags)
         if roads_info[k] and roads_info[k][v] then
             z = math.max(z, roads_info[k][v].z)
         end
+        if not tags["construction"] then 
+            z = 33
+        end
     end
     return z ~= 0 and z or nil
 end

project.mml

@@ -1852,6 +1852,7 @@ Layer:
               OR oneway IN ('yes', '-1')
               OR junction IN ('roundabout'))
           ORDER BY
+            CASE WHEN highway IN ('construction') THEN 0 ELSE 1 END, -- put highway=construction last
             z_order DESC, -- put important roads first
             COALESCE(layer, 0), -- put top layered roads first
             length(name) DESC, -- Try to fit big labels in first

scripts/lua/test.lua

@@ -26,6 +26,10 @@ assert(z_order({}) == nil, "test failed: no tags")
 assert(z_order({foo="bar"}) == nil, "test failed: other tags")
 assert(z_order({highway="motorway"}) == 380 , "test failed: motorway")
 assert(z_order({highway="motorway", railway="rail"}) == 440 , "test failed: motorway + rail")
+assert(z_order({highway="motorway", construction="motorway"}) == 380 , "test failed: highway=construction + construction=service")
+assert(z_order({highway="construction", construction=motorway}) == 38 , "test failed: highway=construction")
+assert(z_order({highway="construction", construction="service"}) == 15 , "test failed: highway=construction + construction=service")
+assert(z_order({highway="construction", construction=null}) == 33 , "test failed: highway=construction with null construction=*")
 
 assert(z_order({highway="motorway"}) > z_order({highway="motorway_link"}) , "test failed: motorway_link")
 assert(z_order({highway="trunk"}) > z_order({highway="trunk_link"}) , "test failed: trunk_link")