street: continental zebra markings at the three signalised crossings

0.5 m white bars with 0.5 m gaps across a 3 m band per crossing, laid
1 cm above the road surface. Makes the mid-block crossing (OSM way
385648319, s=130.1 m) a designated crossing in game. Metadata audit
passes (1 sidecar, 0 problems).

Art/blender/street/street_mesh.py

@@ -18,6 +18,10 @@ Geometry follows the measured profile rather than a guess:
   kerb (see `Geo/verification/2026-11-06-cross-sections.md`);
 * kerbs are flushed to 0.02 m within ±2.5 m of each signalised crossing, with a
   1.5 m blend, so the crossings are actually usable on foot;
+* each signalised crossing gets continental zebra markings — 0.5 m white bars
+  with 0.5 m gaps across a 3 m band, laid 1 cm above the road surface — so the
+  mid-block crossing (OSM way 385648319, s ≈ 130 m) reads as a designated
+  crossing in game;
 * sidewalk widths 4.0 m south and 5.3 m north, from the DEM-derived setback
   arithmetic;
 * the DEM supplies every elevation, so the 3.4 m fall and the ~2 % crown come
@@ -247,6 +251,44 @@ def main():
     kerb_faces(SOUTH_GUTTER, "Kerb_South")
     kerb_faces(NORTH_GUTTER, "Kerb_North")
 
+    # Continental zebra markings: one band per signalised crossing. Bars run
+    # along the road (traffic direction), side by side across the carriageway;
+    # a pedestrian crosses perpendicular to them. Lifted 1 cm above the road
+    # surface (which is itself 2 cm above the DEM) to avoid z-fighting.
+    paint = bpy.data.materials.new("Road_Paint_White")
+    paint.diffuse_color = (0.85, 0.85, 0.85, 1.0)
+
+    def crossing_band(s_c):
+        zone = 3.0        # band length along the road, m
+        w, g = 0.5, 0.5   # stripe width / gap, m
+        span = (SOUTH_GUTTER + 0.2, NORTH_GUTTER - 0.2)
+        verts, faces = [], []
+        n = int(zone // (w + g))
+        for k in range(n):
+            s0 = s_c - zone / 2 + k * (w + g)
+            corners = []
+            for s_edge in (s0, s0 + w):
+                base, normal, _ = at(s_edge)
+                for off in span:
+                    x = base[0] + off * normal[0]
+                    y = base[1] + off * normal[1]
+                    corners.append((len(verts), (x, y, (dem_z(x, y) or 0.0) + 0.03)))
+            # corners order: (s0,off_s), (s0,off_n), (s1,off_s), (s1,off_n)
+            idx = [c[0] for c in corners]
+            verts.extend(c[1] for c in corners)
+            faces.append((idx[0], idx[1], idx[3], idx[2]))
+        mesh = bpy.data.meshes.new("Crossing_Markings")
+        mesh.from_pydata(verts, [], faces)
+        mesh.update()
+        mesh.materials.append(paint)
+        obj = bpy.data.objects.new("Crossing_Markings", mesh)
+        bpy.context.scene.collection.objects.link(obj)
+        return obj
+
+    for s_c in CROSSINGS:
+        band = crossing_band(s_c)
+        print(f"crossing band at s={s_c:.1f}: {len(band.data.polygons)} stripes")
+
     for obj in (road, sw_s, sw_n):
         print(f"{obj.name:16} verts {len(obj.data.vertices):5} faces {len(obj.data.polygons):5}")