Add narrow gauge railways

src/americana.js

@@ -147,6 +147,11 @@ americanaLayers.push(
   lyrRail.railServiceTunnel.dashes(),
   lyrRail.railServiceTunnel.fill(),
 
+  lyrRail.narrowGaugeTunnel.dashes(),
+  lyrRail.narrowGaugeTunnel.fill(),
+  lyrRail.narrowGaugeServiceTunnel.dashes(),
+  lyrRail.narrowGaugeServiceTunnel.fill(),
+
   lyrOneway.tunnel,
   lyrOneway.tunnelLink,
 
@@ -272,6 +277,11 @@ americanaLayers.push(
   lyrRail.railService.dashes(),
   lyrRail.railService.fill(),
 
+  lyrRail.narrowGauge.dashes(),
+  lyrRail.narrowGauge.fill(),
+  lyrRail.narrowGaugeService.dashes(),
+  lyrRail.narrowGaugeService.fill(),
+
   lyrOneway.road,
   lyrOneway.link
 );
@@ -386,6 +396,11 @@ var bridgeLayers = [
   lyrRail.railServiceBridge.dashes(),
   lyrRail.railServiceBridge.fill(),
 
+  lyrRail.narrowGaugeBridge.dashes(),
+  lyrRail.narrowGaugeBridge.fill(),
+  lyrRail.narrowGaugeServiceBridge.dashes(),
+  lyrRail.narrowGaugeServiceBridge.fill(),
+
   lyrRoadLabel.bridgeSpacer,
 
   lyrOneway.bridge,

src/layer/rail.js

@@ -162,14 +162,64 @@ class RailService extends Rail {
   }
 }
 
+class NarrowGauge extends Railway {
+  constructor() {
+    super();
+    this.railClass = "narrow_gauge";
+    this.brunnel = "surface";
+    this.service = false;
+
+    this.minZoom = 10;
+
+    this.fillWidth = [
+      [8, 0.3],
+      [12, 0.9],
+      [20, 3.8],
+    ];
+    this.dashWidth = [
+      [8, 1.6],
+      [12, 4.8],
+      [20, 20],
+    ];
+
+    this.dashArray = [0.15, 3];
+
+    this.fillColor = [
+      "interpolate",
+      ["exponential", railExp],
+      ["zoom"],
+      this.minZoom,
+      `hsl(${this.hue}, 0%, 75%)`,
+      this.minZoom + 2,
+      `hsl(${this.hue}, 0%, 50%)`,
+    ];
+  }
+}
+
+class NarrowGaugeService extends NarrowGauge {
+  constructor() {
+    super();
+    this.service = true;
+
+    this.fillWidth = [
+      [8, 0.15],
+      [12, 0.5],
+      [20, 1.9],
+    ];
+
+    this.dashArray = [0.1, 3];
+
+    this.constraints = null;
+  }
+}
+
 /*
  * TODO:
- * subway
- * light_rail
- * tram
- * monorail
- * funicular
- * narrow_gauge
+ * subway z14
+ * light_rail z12
+ * tram z14
+ * monorail z14
+ * funicular z12
  * preserved?
  */
 
@@ -191,6 +241,22 @@ class RailServiceBridge extends RailService {
   }
 }
 
+class NarrowGaugeBridge extends NarrowGauge {
+  constructor() {
+    super();
+    // Undifferentiated
+    this.brunnel = "bridge";
+  }
+}
+
+class NarrowGaugeServiceBridge extends NarrowGaugeService {
+  constructor() {
+    super();
+    // Undifferentiated
+    this.brunnel = "bridge";
+  }
+}
+
 // Tunnels
 
 class RailTunnel extends Rail {
@@ -209,10 +275,34 @@ class RailServiceTunnel extends RailService {
   }
 }
 
+class NarrowGaugeTunnel extends NarrowGauge {
+  constructor() {
+    super();
+    this.brunnel = "tunnel";
+    this.fillColor = `hsl(${this.hue}, 0%, 90%)`;
+  }
+}
+
+class NarrowGaugeServiceTunnel extends NarrowGaugeService {
+  constructor() {
+    super();
+    this.brunnel = "tunnel";
+    this.fillColor = `hsl(${this.hue}, 0%, 90%)`;
+  }
+}
+
 export const rail = new Rail();
 export const railBridge = new RailBridge();
 export const railTunnel = new RailTunnel();
 
 export const railService = new RailService();
 export const railServiceBridge = new RailServiceBridge();
 export const railServiceTunnel = new RailServiceTunnel();
+
+export const narrowGauge = new NarrowGauge();
+export const narrowGaugeBridge = new NarrowGaugeBridge();
+export const narrowGaugeTunnel = new NarrowGaugeTunnel();
+
+export const narrowGaugeService = new NarrowGaugeService();
+export const narrowGaugeServiceBridge = new NarrowGaugeServiceBridge();
+export const narrowGaugeServiceTunnel = new NarrowGaugeServiceTunnel();