Add interstate shields to style

style.json

@@ -19,7 +19,7 @@
       "type": "raster"
     }
   },
-  "sprite": "https://maputnik.github.io/osm-liberty/sprites/osm-liberty",
+  "sprite": "https://raw.githubusercontent.com/kylebarron/osm-liberty/highway-shields/sprites/osm-liberty",
   "glyphs": "https://api.maptiler.com/fonts/{fontstack}/{range}.pbf?key={key}",
   "layers": [
     {
@@ -1453,13 +1453,67 @@
         "text-halo-width": 1
       }
     },
+    {
+      "id": "road_shield_us-interstate-2",
+      "type": "symbol",
+      "source": "openmaptiles",
+      "source-layer": "transportation_name",
+      "minzoom": 7,
+      "filter": [
+        "all",
+        ["<=", "ref_length", 2],
+        ["==", "network", "us-interstate"]
+      ],
+      "layout": {
+        "icon-image": "us-interstate_2",
+        "icon-rotation-alignment": "viewport",
+        "symbol-placement": {"base": 1, "stops": [[10, "point"], [11, "line"]]},
+        "symbol-spacing": 500,
+        "text-field": "{ref}",
+        "text-font": ["Roboto Regular"],
+        "text-offset": [0, 0.2],
+        "text-rotation-alignment": "viewport",
+        "text-size": 10,
+        "icon-size": 0.8
+      },
+      "paint": {"text-color": "#fff"}
+    },
+    {
+      "id": "road_shield_us-interstate-3",
+      "type": "symbol",
+      "source": "openmaptiles",
+      "source-layer": "transportation_name",
+      "minzoom": 7,
+      "filter": [
+        "all",
+        ["==", "ref_length", 3],
+        ["==", "network", "us-interstate"]
+      ],
+      "layout": {
+        "icon-image": "us-interstate_3",
+        "icon-rotation-alignment": "viewport",
+        "symbol-placement": {"base": 1, "stops": [[10, "point"], [11, "line"]]},
+        "symbol-spacing": 500,
+        "text-field": "{ref}",
+        "text-font": ["Roboto Regular"],
+        "text-offset": [0, 0.2],
+        "text-rotation-alignment": "viewport",
+        "text-size": 10,
+        "icon-size": 0.8
+      },
+      "paint": {"text-color": "#fff"}
+    },
     {
       "id": "road_shield",
       "type": "symbol",
       "source": "openmaptiles",
       "source-layer": "transportation_name",
       "minzoom": 7,
-      "filter": ["all", ["<=", "ref_length", 6]],
+      "filter": [
+        "all",
+        ["<=", "ref_length", 6],
+        ["!=", "network", "us-interstate"]
+      ],
       "layout": {
         "icon-image": "default_{ref_length}",
         "icon-rotation-alignment": "viewport",